Django Rest Framework Series - Build a Django DRF Quiz API - Part-1

hello and welcome back to another django drf project this time is going to be a quiz project so we're going to be building a quiz api essentially here but really the essence of this tutorial is i wanted to show you a little bit more about serializers so so far really what we've seen in at least my tutorials is that to you to use a serializer we select the data from the database that we want and normally that's from one table we put it through the serializer and again we're just using one table so this really is a showcase or or taking that one step further and thinking about multiple tables so utilizing serializers where we're collecting data from multiple tables and this kind of setup really kind of leans into kind of demonstrating some of the other django tools that we have available functions that we have available to actually perform these type of operations so we go through the process of building a simple quiz api uh we'll go through the process of developing the models i'll give you a few different pointers that i haven't mentioned before about models and then we'll create some simple views and serializers so at the end of this tutorial we have some end points so we'll be able to uh from a front end we'll be able to grab all quizzes from our api we'll be able to grab maybe a random question from a particular topic and then all questions from a particular quiz so this will be a standalone tutorial we don't have any front end here we're going to be utilizing postman just to kind of grab all the data or the django api view just to grab the data and show you that the data is being returned here and then in the next tutorials we'll have a look at maybe then just creating a simple front end to consume the endpoints but like i said really the focus here is on those handling relational data particularly foreign key setups in your serializers okay so i'm going to try and make this into sections so you can easily skip ahead so step one as you might imagine we're going to need to create a new project so i'm going to create a new virtual environment start a new django project create a new app called quiz and then install drf so that's pip install django rest framework so by all means do that yourself skip to the next section otherwise let's go ahead now and do this so i'm using windows so i'm going to go ahead and i've already created a new folder called new quiz django live not too sure why i'm using capitals just damn uh so let's just call this vmv oh what am i doing minus m pmv and we're gonna make a new folder called vmv which is a new virtual environment okay so now that's done let's just activate this there we go okay so now we can go ahead and pip install pip install django so make the django project or django framework available so once that's done we can now then use the django admin command of django admin and then create a start a a new app and let's call this core and i'm using the dot so it appears in this folder and doesn't make a new folder inside of a folder oh that's strange so now we can start a new project so i just uh cleared that for you so you can see this so django admin start project and i'm going to call that core and use the dot so that appears in this folder and doesn't make a new folder inside of a folder so go ahead and do that so i've now got a new folder here called core and obviously my settings so now we can create or now we can use the manage pi file so py manage file pi manage pi file and then we can go ahead and uh start app and we're going to call this this app quiz so let's go ahead and do that so make a new quiz app and then of course i need to just register that in the core settings as per normal i'm just going to call that quiz so that just registers the application with django so when we start migrating tables etc it will pick up all the models in the models table or the models pi file okay so that's that done and we need to also install drf so let's go and install that so pip install remember the pip is the package manager for python which allows us access to softwares that we can install so this is going to be the django rest framework we're going to install now once we've done that what we can do straight away if you like is we can make a requirements file that's going to be handy if we want to replicate the application so pip freeze and then the right chevron and then we're going to call that require prince.txt you can call it whatever you like but we're going to call that requirements.txt and that's just going to create a new file here called requirements with all the different dependencies and applications that we have to create this application or that's needed to run this application okay so that's about it really was step one we've created our new virtual environment creating a new project we've installed install drf okay so probably one last thing that we need to do is just to actually include the rest framework into our application so let's go ahead and go into the settings of our core and then here we're just going to also now add the rest framework so we include that in the applications and let's just go ahead and do our initial migrate why not so let's just go we're going to apply all the different tables that django has from the installed apps that are needed for the application so that we can set up our admin area and so on um so that's now in place so we've migrated the data to a new database it's right here now i've got the sqlite plugin or extension installed in visual studio code that's going to allow me to right click open the database and i can actually then see inside my database and inspect the tables and data so let's just go ahead and create while we're here um let's create a a super user so that we can log into the admin when we need to so i've just called it admin and admin don't need an email address it's not a mandatory field and there we go so let's just go ahead before we move to the next stage just make things make sure things are working just do a run server and that's going to show us that our server is now running there's no problems if there were we'd probably receive an error right here so now we have our project set up let's go ahead and actually build our models i was going to take you through the process of normalization but because i'm focusing particularly here on foreign keys i've gone for a model uh built around foreign keys essentially here so let's go ahead and now build our models so just to speed things up and i don't particularly like watching people type in i know that some of you have mentioned or you do prefer that but i'm just going to go for the copy and paste method and just explain what we're doing so first of all we're going to create our main classes or our main tables that we're going to need for this quiz so like i said i was going to take you through the normalization process but i spent a couple of hours trying to to do that and then i realized well i just want to show you normalize i just want to show you foreign keys really so the normalization process would have taken us down a slightly different route in terms of the model set up here so we've got we're going to have four main tables so we're going to have the category table we're going to have a quiz table um and then we're going to have a a question table so we're going to hold all the questions in one table and then finally we also include the answer table so let's go ahead and do that okay so those are the main tables that we're going to be utilizing for this project or at least at the start of this project so by setting the models up in this way you can probably see that we're going to have many to one relationships here so we're going to have all one to many one category in many quizzes there's going to be one quiz many questions for that quiz and then in one question there might be many answers so what we got here are foreign keys linking back to the previous table so just let's go ahead and just add that in so we've got here a category field that's going to have a foreign key to the category table so we've added default option so by default when we add a new quiz it's going to have the category of whatever the first category we place in the categories table is and then you can see here on delete do nothing so what we don't want to happen here is that if we delete this quiz it also deletes the category so we just don't want that to happen so imagine we build a quiz we've got a category say django and then we build a quiz and then what we do is we assign that django quiz to the category django and then we delete that quiz and then what would happen maybe uh utilizing the default setting is that the category would also get deleted so we just simply don't want that to happen so really just as a default we're going to do nothing if a quiz is deleted so um that's not how we might want to finish this table but just for now that's going to be the case for all of these tables here so we've got the question so there's going to be one quiz and multiple questions so let's go ahead and just add in that foreign key so again i'm just going to cop and paste this in i've already written this out so there we go so same situation again so now we've got a many-to-one connection between the questions many questions one quiz or one quiz and many questions and then finally the answers so the same type of situation here we're going to use a foreign key again so this time we're going to just call this question and that's going to be then connected to the question table a foreign key so many to one so one question will have many answers so because we're using the django rm there's a a little bit of abstractness here in the way that what we can do is if we find information in the quiz because we've got that connection here this foreign key connection between question and quiz we could also with the quiz data work out what questions are attached to it because we've got this kind of connection here this foreign key that connects this model or this table to this table so django works in a way that we can collect data backwards and forwards from this kind of relationship here so if we were in questions we could find out what the quiz related data was that's connected to the information we wanted to find about the question and then similar if we created a quiz and we wanted to know all the questions because we've got this foreign key here although it's stated here and not in this model here it doesn't mean we can still find information about the question from the quiz and that's important to understand once we start looking at the serializers we'll be doing exactly that we'll be um collecting all the data about the quizzes and then be able to make through this connection find all the information about the questions as well so now we've got all our relationships in place uh let's just go ahead and fill this in with all the other information that we're going to need so the category all we're going to have in the category is just name for now um and then we're just going to return the string method here done the method uh just the name of the category so that's going to be the default string that's returned from for that table or that model so what you will find with data or how the data or this code is structured inside the models is that there is a or some people do follow a general kind of schema uh in terms of what data goes first inside of your model class and of course that then just nicely organizes it and standardized the way that you can read through the model so i'm just going to place some data here which typically is kind of out of order from those type of schemas or ways of working so we just add some class meta here so if you're not already familiar with this so we've got this verbose name um so we can kind of rename the table so our table might be called something like this might which might be really handy for when we're working with queries etc that might be really handy but when we actually want what we want to actually display in our software um that might be slightly different so or how we might want to refer to this model might be different so we can set the verbose name and also the plural name how we want to display in plural now this is a good example here of utilizing the plural name because quiz will normally just be pluralized by django like this with an s on so this way we can actually do this correctly and then there's lots of different other meta options available ordering is just one of these so we can set the ordering so that's just in class meta and let's move on to the next point so let's go ahead and now just add a let's add a title okay so um you'll notice already that you're starting to see some of these underscores everywhere so the whole point here is that our application might need to get translated so enabled or to order to kind of aid that translation we can identify what might need to be translated so that's really the short version of a longer story so you can see here that i've imported django utils translation import the get lazy so if you want to research this have a look up and get text lazy so this is a tutorial that i've been asked many times about um looking at how to do translations um it is something that i will definitely look at in the next couple of months so we're just uh importing that in as this underscore here so anytime you see an underscore before a name that's something that potentially might get translated so i've just added some other attributes here just to show so we've got the verbose name here um so you can see that we can also kind of make a different name or generate a different name for this particular field um utilizing the verbose name for example we've got the max length at 2 5 and we've also got the default option so have a look at those um it's worth understanding or maybe sometimes including some of those different items so default is what's going to be included in the field by default so we don't place anything in this field it's just going to say new quiz so we've got that now in place the title we've got uh category so what else we're going to need here let's just go for date created so like i said this is just going to be a skeleton set of um fields for you so we've got the um date created and here i'm using auto now add okay so there's two options here um if i remember there's auto now and there's auto now add so auto now is this an auto now add so the difference here is that when the model is initially created that's when this date is going to be automatically generated so automatically when it's added so when we do an update that won't get updated however if we set this to auto now that means every time we update the model it will then get updated so essentially what we're doing here then i guess is doing date created if we do date updated then that's where we're going to use the auto now instead of the auto now add okay so we've got that in place so that's all good and now we can go ahead and add in the string done method to return the default string for this table um so that's all in place now so that's what we're doing for the quiz table you can of course add your own fields if you want to so next thing i just wanted to show you an abstract base class so an abstract base class these are going to be useful when you want to put for example common information or the same information into multiple tables so here is an opportunity opportunity to use one so for example when we update a question we want to record that it's been updated when we update an answer we want to record that it's been updated so we can keep track of when the answer and question has been updated so let's go ahead and just create a new class here we're just going to call this update uh let's just call this update time or just maybe updated that probably do so here we're just extending from models again as we normally do and now we can populate this as we would do a normal table so we're going to just call this uh date updated so it's just going to be a time date uh time date time field sorry um so we've got the auto now true so that's going to mean that when we update the item it's going to automatically update the the date time field with that new timestamp so we can also set the class meta so we'll say abstract equals true so this is going to be an abstract class okay so now what we got and notice here it says update question let's just change this to updated so instead of now extending from models dot model we're now just extending from this abstract class here or this abstract model that we have here and we're just going to basically import this in to question and answer so it's just going to be automatically generated in that way so to confirm we don't actually have to reference this now within question and answer literally this is just going to be utilized when we actually create the model you'll see this that there will be an entry in question and there's an entry in answer okay so moving on to question this gives us a little bit of an opportunity to utilize some other tools so let's just set the class meta again again i'm just going to put this up the top just for now there we go so we've got the name the plural name the order for example and now we need to think about some scales uh because we what we want to do is make a select option so the question will probably have different scale of uh difficultness if that's difficulty sorry so let's go ahead and add a scale for that so typically this is what is found at the top of the class or the first item that's normally described at the top of the class so we've got this nice scale here and notice that what we're doing here is we're utilizing the facility before the translation tool so we've got fundamental beginner intermediate advance and expert because all these items here will potentially be seen by the user so potentially they need to be translated into their own languages etc now this type of format here behind the scenes fundamental is referenced as zero beginner one intermediate two three and four so we've got this kind of numbered scaled here behind the scenes and this is what the actual user is looking at so i prefer to work this way because it's probably easier uh and performance wise potentially to query numbers rather than these words here i say that very lightly so we've got this scale here you can probably see how that's going to be working now i also want a type so in addition to scale i want to know what type of question it might be because later on we might extend this into different types of questions so multiple choices um gapped choices uh other types of questioning that you might want to to utilize true or false for example in your quiz so i've also got a drop down for that too and that's really going to be really handy to sort out some logic later on so we've got the foreign key in place so i like to normally just utilize that first at the top so i can see and i'd have to kind of drill down to the rest of the fields to find any foreign keys so any kind of dependencies fields will be at the top of my model so we're going to just add some more here now i'm just going to kind of bulk fill this in save a bit of time so here we've got technique um and you can see here that's going to that's referring to the the choices so here we've got uh choices and we selected type so these are the choices right here and we've got the title the difficulty so this comes from the drop down option scale so these are all the options that are available for scale so that's going to provide a nice little drop down and we've got date created and then is active so we want to be able to kind of turn on and off the questions so to make them available or not so we'll finish that off with our dunder method to return the default string for this model and there we go so we have our question table now so that just leaves our answer so here we're just going to same type of process let's just add some some meta in and then we've got our foreign key and this time probably what we're going to do here is just add two things the answer text and then whether the question is right or not now that's a little bit contentious is right here um so but essentially if you can visualize this this table is going to have the question id and then the question and then that's also going to that's obviously connected to the question so question one whatever and then the answer will there be say multiple answers here recorded via the id of the question and then one of those that are connected to that question will be flagged as is right that finishes off our models for this project so only one thing i didn't mention that i was going to talk about was normalization so if you do happen to want to learn a little bit more about databases and formulating database schemas and tables etc it's well worth having a read through normalization it's going to ultimately make maintaining and changing your database more effective and has effects on performance or can improve performance and efficiency of your database and also another area to look at is database anomalies so the idea of structuring a database is to ensure that you protect yourself against some common database anomalies so for example update anomaly next up we have admin so i'm just going to take you through a small activity where we're going to utilize inline model admin objects so as of making this tutorial this is something i've not mentioned yet in this channel so this is a great scenario in order to actually apply or to introduce this topic to you and this is essentially going to allow us to edit models on the same page as the parent model so that's a description from django so essentially what we can do here is we can take two models that are connected in this case we've got the many two one connections and the foreign keys we can take these two models and we can put them on the same form or the same page and we can then update both of those models at the same time so if you haven't already done so now's a good time to migrate the data um i can't remember if i've done that so make migrations okay so then go ahead and just migrate and then if you haven't already got a super user just create a new super user i'm just going to call mine admin and admin there we go so let's just start the server back in the admin let's go ahead and just delete what we had previously if you had anything in there and i'm just going to now add a registration here for the category so i've created this new class here called cat adam in and i'm listing just the name in this case it looks like so let's just go ahead and have a look and see what that looks like okay so i've registered that so there's no categories there at the moment and then let's go ahead now and register a new table so this time it's going to be quizzes so here you can see that i'm just going to display the id and title in the list when we looks like when we create a new quiz so that's what's going to be displayed in the listing and then underneath here we've got answer inline model that's the name of the class and then here we're extending from admin and we're going to use the tabula inline so if you take a look through the django documentation you can see that there's two subclasses of the inline model admin their tabular inline and stacked inline of course we're going to be utilizing tabular inline here and like it says here the difference between them is merely just the template used to render them so let's just uh go ahead and use the tablet inline as i described earlier this is going to essentially allow us to take data for or use two models and put them on the same page and that's going to come a little bit that's going to be made a little bit clearer as to why we're using that in a second so let's just go back to our code so you can see see here that we've registered the quizzes we've got some listing the display of the quiz so when we created a quiz it should list just the id and the title so let's just go ahead and do that so i've added it already and i'm gonna just refresh and you're gonna just see the id and the quiz title there we go so i've added a new quiz and some new categories from here already so what we now need to do is just go back so now what we've done here you can see that we've created a a tablet inline okay so we've selected the model that we want to use the answers so it looks as though here what we're going to do is we're going to put the answers on the same page as something else in this case it's going to be the question because what we want to do is when we make a new question is we might as well add the answers while we're there there's no point then coming out going back into the other table and then making the answers we might as well do it all on the same page so you can see i've selected the fields that we want to use and there we go so we need to kind of define this first before we go ahead and use it so that's why we've done that so um let's just go back to here and now we've got the um the question so we're just going to register the question so we've got some fields here that we're going to register so we're only going to see the title and quiz field um when we actually build a a new question we're only going to see the title and the quiz and this is what we're going to list when we're listing all the quizzes sorry all the questions sorry and this time when we build a new question we're also going to put in line the answer inline model and that's the name of the class that we created earlier that's connected to the answer so essentially what we're doing is we're saying that on the question page we're going to use an inline and we're also going to insert the answers and that's just been extracted here included here by this class so the last thing that we'll do is we'll just add the the question so we can just access all the questions let's just register that and there we go so that's going to be our uh admin pi file so let's go ahead and have a look now at this in action so like i said i've already had some categories and and i think a quiz yep so we've got a new quiz here so let's go into questions so we add a new question and here we go so what you're seeing here is the model uh for the question and then the model for the answers so we can add data all at the same time so let's call this question one this is from the new quiz that we've just made so the answer one answer to an answer three and here i can define if it's right or not and i've got the option to delete so this is just something that the admin page has automatically generated now behind the scenes what's going to happen is that when we save this it's going to save the question and also the answers now remember that we've got a foreign key between the answers and the questions so there is a link between them so django or the back end is able to work that out save it appropriately and there we go so if i now go into the cool answers uh you can see we've got answers here and they're connected to the question so our final step really is to now create some views and some serializers so that we can pass the data over to the front end now what we're going to do here is in this example is just create three views or three endpoints for our api system one to gather or to yeah collect all the data about all the quizzes so if we want to find out what quizzes were available we're going to use that endpoint then we're going to create a random question endpoint so we can select a random question from a topic and then finally we do that a question from a particular quiz so you'd assume that the user would on the front end pick a quiz and then be presented with the questions and obviously all the answers and they'll be able to click through that one by one and answer all the questions i suppose it's worth noting here there's two strategies here for the front end so do you allow the front end to access a question at a time so for example your api would request question one from the system that would be returned and then question two and three and four or do you choose to uh basically just find all the questions related to that quiz take that and put it all onto the front end and store it on the front end and just kind of iterate through all of those questions i guess that's a decision that you need to make now here we're just really talking about text probably a very small amount of text or data so it's probably worthwhile actually collecting all the quiz questions and answers and then saving that in state on the front end that's probably a better answer because once you start scaling this up you imagine if you've got a million people uh trying to do a quiz that's a million requests every single question rather than being a million requests per every quits so you're just cutting down on the amount of bandwidth and potentially a lot of cost savings there to be made but that's obviously a choice that you can make so before we start building our views uh let's just go ahead and create some urls so uh in the core we're going to connect the urls to our quiz so here you can see what we've done is we've included we've added include so we can use the include and then we're just going to include the quiz url so we're going to name space here and then you can see that the path is going to be quiz so if we want to access our api we're going to use the quiz in the url to extend the the default path and then let's go over now to our quiz in the urls so now we've added the app name and because we've provided a namespace we've imported from the view the quiz that's going to be our first view that doesn't exist yet we'll do that in a second and we're going to be using class based views so here we've created a simple url pattern of the default path so if we just type in quiz after the default url that's going to take us to this path and here we're going to then collect or perform what's in the view called quiz so we're giving it a simple name and i think that's all we need to do there okay so let's go over to the views so nothing currently in the view so let's go ahead and do something here so first of all we're going to start off with creating a simple kind of a list of all the quizzes so we are going to be using class-based views so let's bring in the rest framework tools in this case we're going to bring in the generics so in the first instance here we're going to use the list api view um so let's bring that in and then what we're going to need after that is probably a class i guess so let's go ahead and build a new class for this so let's just call this quiz and then we're going to extend from generics and we're going to be utilizing the list view api so we don't need to create anything or anything crazy like that we're just literally going to list items so in this case all we need here is a serializer class so we're going to need to make that so we'll call that quiz uh serializer and then we're going to need a quick a query set so we're going to say we want all the data from the table quizzes okay so that just collects all the data so obviously we're going to need to bring that in so from from models import and this time it's going to be quizzes okay so we brought in the model that we're going to need so that's pretty much it really so we're just collecting all the quizzes from the database putting in the query set and because we're utilizing this list api there's a lot of abstraction here but behind the scenes that's going to do everything for us in terms of sending it over to the front end so now you might imagine we're going to need a serializer so here we called our serializer for this data quiz serializer so let's bring that in from our serializers which we need to build so i've made a new file here called serializers okay so what i've got here from the rest framework i've imported serializers and then i've gone ahead and i'm going to need the model so i've imported the model that i'm going to need so i'll create a new class i've called that quiz serializer that matches up with everything in the view and now i'm just extended from serializers and we're using model serializer so what's happening here if you're not familiar with serializers is in the view we collect all the data from a database now the thing is here is that if we collected this data and sent it across to the front end via the api the data wouldn't be formatted in a way that could be util utilized by the front end because typically we're going to be utilizing json on the front end so we need to format the data in a way that jason can oh that jay javascript sorry can handle so we will utilize the serializer serializer is basically going to um take that data and then make it or format it in a way that can be utilized in the front end so let's go back to serializer and you can see what we've done here is in the serializer we've created a class meta we've selected the model we want to use quizzes and the data that we want to collect so this case we're just going to collect the title and then push that over to the front end so before we can see this in action you can see that maybe there's a an issue here in the view so we just remove that comma uh looks like it might be okay now so let's go back into the front end now what i do have is so look quizzes we've got one quiz so we're only going to see one quiz now remember the end point was uh our what here so our endpoint was just a quiz and there we go so one item is being displayed because we have one item in the database i think that's pretty simple so let's just open up a a new tab here for the admin so let's just go ahead and just test that so if i create a new quiz of course new quiz 2 press i'll make it into a react quiz press save go back to the front end you can now see we've got two quizzes so clearly that end point is working for us and that's returning all the the quizzes are available in the database so let's have a look at creating some sort of random question from a particular topic so we're going to utilize i think api view for this this might be a good example of api view so whereas we've got these list api views from the generics that's going to provide a lot of abstraction here it does a lot for us you can see all we need to do is define the query set in the serializer it just works so with api view we can be a little bit more descriptive and we can provide more information and be in a little bit more control as to what's happening so let's go ahead now and just create our our random for this so this time we're going to use like i said the api view so um let's just call this a random quiz or random question and then this is going to be utilizing the api view so when is this going to be utilized so here we need to define the request type so when for example we send a request to this endpoint that we're building here and that's going to be a get request so we're going to need to perform an action based upon our get request so we'd call this a this new function get say and then let's take in cell from request has taken all that information into this function so we can utilize it within this function um we can define the format is none and then we can also take in the the quarks the additional arguments or additional data that we might be sending in and we will be doing that and this is why we're doing it this way just to show you this so if you're not too sure what args and quads are there is a good tutorial in this channel which i'll explain and give you a brief overview quite in-depth overview of what these are and how they potentially work in django so talking a little bit about selecting a random item from the database so there are many different ways we can do this we could for example and where possible you always want to try and put as much in the model as possible and keep the view light as possible so there's a lot of things we can put in this model so for example if we knew that we wanted a particular in this case random we could set out maybe a custom manager for this or we could set our custom function to uh generate a a random item from a database now this case we're not going to do that i'm just going to keep it into view and just keep it nice and tidy really i'm not trying to make this into a feature selecting random items from a database so we're going to keep it nice and simple and we're going to use order by i'm going to show you how that works in a second so we could have like i said we could have done this in many ways but this seems not the easiest way to do it so we're going to collect a random question from the question let's bring in from the models uh question oh so from question so that's where all our questions are stored we're going to use a default manager and then filter so we're going to make a simple filter okay so like i said we want to select a specific question from a topic that's defined so the user will define the topic and that will then be um indicated in the url and what will happen is that that word that topic that's been selected we'll go across into the quarks here and we're going to utilize or extract that out and we're going to utilize it in this filter so we can select the particular so in this case the topic is basically going to be the the quiz name or the quiz title okay so the quiz title is going to be called django or it's going to be called uh react for example so this is just first for demonstration purposes so what we're going to say is that if we look at our model here in our in our question if we go down to the question here we've got a foreign key and that foreign key is connected to uh quizzes okay so our quiz has a name so let's draw this back up to quiz in quizzes we have title so what we're going to do is going to filter based upon the title the quiz that's what we're going to do sorry if that was confusing so because we've got that connection between the quiz questions and the quizzes we can access the quizzes title so we can run a filter on that so let's go back in here and so what we're going to do is say quiz and then use a double underscore so we can access the the quiz so we're working backwards from the question we're now inside of the question model say and now we've gone to the quiz field which is a foreign key and we're using the doubles here underscores to say we want to move backwards now into the quiz table and we want to select in the quiz table the title so that's going to equal our quarks so remember we're going to send across from the url for example django and now we're going to filter and get a question from based upon the quiz title being django so any question which if you roll back to the quiz model is inside of the django quiz so this is going to be we're just going to call this uh topic so that's what we're going to name um the quarks so any data inside of topic and now we're going to order so this is going to provide the this kind of random element so we're going to collect all the questions from the in say django or the react quiz and then we're just going to order them and this is going to basically uh make a random order so we say order by and then we're going to utilize the question mark and that's going to make a random order and of course we only want to select one of these items because we only want one question at a time so let's go ahead and just i'll just kind of slice it really and just select one of those items and there we go so that will create a very simple uh random question so in terms of this quiz it's effective and it's uh it's not going to be too costly here because we're only running one query and there isn't going to be too many questions that we need to run through so that really isn't going to be a problem in this case so let's just uh go to the next line here so now we're going to need a serializer of course so let's bring in our serializer class so we've got a serializer we're going to call that a random yeah let's call that random question uh serializer so let's just connect to that and then we what we need to do now is we need to pass in the data from that we've collected from the database so that's in the variable here question and then we're going to say many there are many so many equals uh true and then we're just going to return that so return we're going to use the response which we need to bring in to the project and then serializer.data we're going to send the data back so there we go so let's just bring in the response in from the rest framework okay it's pretty rainy outside okay so there we go that's um that set up so now we need to go into the serializer and sort that out okay so let's bring in the question let's do that first so bring in that model and now make a new class uh we need to call that a random random question serializer and let's just bring it in while we're here in the view so let's just give it as a model so in the serializer we're going to call this random question serializer and like before we're just going to extend from serializer there we go so let's do something here let's just go ahead and just create some class meta very quickly there we go so we obviously want to use the model question and we want to return the title and the answer okay so before we do anything special here let's just go ahead and create a new url for this so we're in quiz in our urls so let's just uh build a new url for this now what we're going to need to do here is we want to take in a parameter because what we want to do is we want to take in the parameter of the actual topic or the actual name of the quiz that we want to find a random question from so here we're going to set up a a returner string and we're going to remember call that topic so that's going to be the um like a variable really that we're sending across a and that's going to be referenced by topic so that's in place and then of course we now just need to connect that to our our classic so that was called random question so let's just bring that in first into our urls and then we can utilize it right here and then dot as view okay and then we can give that a name of course so let's just call that a random okay so now we've got our url in place let's just see this working so remember we need to say quiz r for random and then we need to the name of our topic so remember this topic name is going to be utilized and passed in and we're going to be that's going to be stored in the class quarks and then you can see what we're doing we're going into the quarks and we're looking for topic and this filter which is built wrong that was a good spot that's going to filter based upon the quiz title being whatever the topic name is from the url okay so let's get back in to our quiz here so we need r for random and then say django so at the moment we are missing one required positional argument so let's have a look to see what the problem is here so just fixing that little problem format equals none and also just making sure that the filter was called filter spelled correctly so once we've done that we can now go back into our view and you can see that our random question generates no data at all at the moment so obviously we don't actually have a quiz called django so let's go ahead and actually build this new quiz it needs to be called django and let's press save it's going to be in the category of django um and we can just quickly then make some few a few questions for this let's call this uh q1 of the django quiz and a3 okay so we've got a question and we've got some answers so let's now go now go back and refresh and you can now see what's happening here is that from django we've actually collected one question and that's the question we've just made so uh notice as well we've got an answer that seems pretty cool so we've now got a question and an answer so let's go ahead and just uh build another question just to see if this is working properly so inside of my questions let's go and build a new question so let's call this question two and this is going to be for the django uh so we've got a1 a2 and a3 again so let's go back to here and refresh and you can see that if i keep refreshing i get a random question being generated so you can see what's actually being returned isn't very useful because the answer is just returning four five and six now i'm pretty amazed that this is working actual zack i would have guessed that or would have said that this wouldn't work because all i've done is randomly uh typed in title and answer here into the serializer now answer's not actually referring to anything and i can see no so um somehow django is working out um what the answers are obviously utilizing the foreign key but there isn't actually a reference to answer here because our answers in the model if i go back to the model uh are called answer text so the only thing that's called answer is actually the table but that's got a capital so that's a little bit strange but uh nevertheless um you can see that isn't what we need so we need to think about collecting more uh data that is more appropriate to sending across to the front end so here we introduce serializer relations so this is going to be a way of collecting or utilizing relational data within our models so from our serializer we can collect utilizing our serializer relations as long as there's a relationship between the the two tables we can collect information from it potentially so let's have a look at some of the options we've got the string related field so it can be used to represent the target of the relationship using its string dunder method right so let's just utilize this first so let's go back and into our serializer let's go ahead and create an answer so the answer equals serializers uh string related field uh many equals true so we're going to use the light of the string related field so we're going to serialize that put into answer and then that's now connected here so that should output that information now what's happening here it says string related field so let's go back into the model now down here in our answer we've got we don't have the dunder method so let's just put in the dunder method here and let's utilize the answer text so we're going to return default the answer text from our answer table here or our answer model so let's just give that a go and see what now gets returned and there we go so we've got a1 a2 a3 so it's utilizing that foreign key to work backwards and then to actually find the answers so we actually have the answered text here now that's not always going to be um something you want to do because yourself your your dunder string method here might be completely different so let's just show that that is working now this is going to cause an error you would imagine because it's not going to be a string yep okay so it will only return non-string only return string method so let's go back here and obviously the question that should just be an id so let's go for that okay so that's not gonna work either um i was hoping to show you something else but uh clearly what's happening uh take from me what's happening is it's utilizing this uh done the string method here and returning what the default string is returning in this case it's the answer text and that's where we're receiving the answer text here so hopefully you get the idea here so you can work through this now you've got primary key related fields you can collect hyperlink related fields that's going to be uta useful to return hyperlinks so if we had a slug for example in the um the quiz table if we utilize this slug we could return back the url and that would then make a link to the actual quiz from the um from the quiz link so for example we would go on our front end to the page which shows all the the quizzes and then we would also send back the the url for that quiz so that when we click on that quiz we can set it up and utilize that url to then actually go to the quiz and start the quiz obviously this link here would be appropriate so it'd be captured within our api system and it would actually be an end point to the start of the quiz so just looking through this we've got the slug related field it's worth having a look at and the hyperlink identity field so it all these the same type of principles just need to read through um hopefully you can see what's happening now with those um so those are available for you to utilize so the only thing that really might need an explanation or an example is the custom relational field so what we can do here is we can well we can do this for example so let's just go back into our serializer and let's just now make a new serializer for the answers so um this is going to be above the uh random so we want to bring this in first so here we're going to create a new serializer called answer serializer we're going to use the answer model so we need to bring that in and basically that's going to collect all the information from that model in this case the id answer text and is right so that's the information that we probably want to pass over about the question to the front end right so what we need to do now is well just uh just link to it really and that's pretty much it so let's go ahead and now store that there so we link to it there's some properties here which you can have a look uh on the website what they mean and there we go so that's hopefully now all this information here will now be brought into this variable and serialized ready to put into our model and then this will then be shipped across to the front end so that should be much more functional information for our front end so let's go back and refresh and there we go so that's much more effective now this has been sent to the front end you've got the actual title of the question that's the actual question a text you've got the answers so you've got an id and an answer text and whether it's right or wrong whether it's true or false and there we go so that seems like a a good way of working if i keep refreshing you can see that it's going to collect different questions within that particular quiz there we go so a random quiz selector so that just leaves our last view to build and that's collecting all of the quiz questions from a particular quiz so that should be pretty simple now because we can just re-utilize our random question here so i've copied and pasted called the class uh quiz question now and this is going to be a get request again we're going to take in some quarks so here it's not going to be random anymore but we are still going to take in all or gather all the questions from the particular title so from the django um quiz or from the react quiz or whatever so we just basically don't need the end part here where we order the items um and then we're going to create a new serializer let's just call that quest question serializer um yep let's just call that question serializer and that's going to take in question here again and then we're going to send out a response so that pretty much seems all that we're going to need there so let's go into our urls so let's just build a new path or an endpoint for this so this path unless again just let's just copy this um in this case there's not going to be a random it's just going to be a selected quiz so i'm just going to use q here and you can change that path you want so we're going to take in topic again and now this time it's going to be called i think it was quiz question we named it yep okay so obviously we need to bring that into the urls there we go and let's just call that a quiz [Music] questions there we go and now that's all in place so now what we need to do is go over to the serializers so we called this serializer question serializer so we need to bring that in to the view first and then go over to serializer let's just create a new class here we're going to call that question serializer as per normal and then we're just going to import again our serializer model serializer and so at this point we're literally just copying and pasting what we previously done we could probably almost use this serialize apart from one item but you want might want to change and so if we put this in here let's just go back to the views just to confirm what we've got so we've literally got the same as the random question without the randomness of ordering and that's going to return all of the questions and then in our serializer we're doing exactly the same thing again we're going to collect all the answers and we're going to use the model question to get all the questions and then all related answers so let's just take a look at what that looks like so here we are you can see that we're collecting the title of all the questions and all the answer data obviously though if there was more data that would would have more data obviously sorry um so we've only got two questions inside of our quiz at the moment so that's why we're returning only two items so obviously one thing we're missing here is the title so the actual we want to pass across to the front end the actual title of this quiz so again we can just i'll just stitch this together right because we've got the information up here so let's go ahead and just uh copy this that's the wrong one uh let's go ahead at the bottom here our quiz serializer and we'll just copy this down we call this uh quiz how about that and then now we want to use this serializer here so the quiz serializer is going to collect the title of the quiz now because there is a relationship between the question uh in the model and the um quizzes table it means we can access that information so let's just change here to the quiz serializer and then of course we're not returning more than one item so it's not iterable at all so we many equals true is false so we will take that out for now and there we go so what we have now if we return back and we refresh is a broken serializer okay let's just go back here um what's missing here uh quiz quiz okay so actually let's bring it in because we haven't actually brought it in yet so let's put it at the front here so that's going to return that um is that going to fix it i didn't read that yeah okay so there we go so now we have the quiz title and all the quiz questions and it is returning the quiz title on on each question um but that's okay for now and that isn't too much of a an issue so yeah there we go so we now have all the data that's kind of valid we could definitely utilize this now and send it across to the front end and build a a quiz so i do hope that's given you some insight into working with foreign keys and handling relational data with inside your serializers to kind of expand the data that's returned to the front end in addition to that hopefully you've learned a little bit more about the admin and how you can use multiple models on the same page or within the same form set hopefully that was useful too so we do have a functional quiz api now obviously there's no security here there's lots of more things that we could add obviously to this hopefully this is kind of a baseline to help you move your knowledge forward and start to utilize data and to start to kind of put data together to send across uh to the front end so naturally the next step in this series would be to create the front end to handle all that data and actually and actually create some sort of uh usable quiz application so if you are enjoying the tutorials and you want to support the channel further then please join our community our membership community if you go to the home page select join uh you can join as a member to our channel and support our channel further okay so thank you very much and hopefully i'll see you in the next tutorial

Channel: Very Academy

Views: 14,039

Keywords: django, django rest framework, django framework, django rest, djangoproject, django react, django python, rest framework, django cors, django tut, django tutorial, django 3, django examples, learn django, django beginners, beginners django, django 2020, django example, quiz api, django api

Id: 8QLCaye3YjQ

Length: 66min 47sec (4007 seconds)

Published: Wed Nov 11 2020