Create your FIRST CRUD RESTful API - Java, MySQL, Springboot, JPA, & Maven

[Music] what's up guys welcome back to another video today we'll be creating our very first crud restful api using java mysql spring boot jpa and maven be sure to like this video and subscribe to the channel so you guys can see all of the new content i've been posting it's much appreciated so to actually do this tutorial you'll need java maven and mysql workbench installed on your machine i'll provide all of the links in the description box so please check it out and once you're done with that you can come back here and resume the video so once you're all set with all the things we need let's go ahead and start so now let's get started let's start with an api so basically an api stands for application programming interface an api is a set of rules and mechanisms by which one application or component interacts with others so what exactly is a restful api then rest is an architectural style restful is basically the interpretation of it so essentially the design of a rest api will look like this you have a client a ui for example this ui calls an api the api will perform operation on the database like creating data deleting data updating data and reading data so a rest api has four major operations receiving data in a convenient format creating new data updating data and deleting data so this is exactly where the crud acronym come from in crud the c stands for create the r stands for read u is update and d is delete so how do apis actually exchange data json is something that's used to exchange data with restful apis json stands for javascript object notation we can send json to the server to create update and delete data when we read data we can also get it in a json format this is great because json is compatible with all programming languages meaning that when we're using restful apis we can communicate with any application no matter what the app was actually written in so this is awesome rest also relies heavily on the http protocol each rest operation uses its own http method and http get request is when you are receiving any kind of data for example when you simply browse to any url you are actually performing a get request this corresponds to the reading crowd an http pulse request is usually the creation of data so submitting a form on the user interface or any other client would be considered a post this corresponds to the create in crowd an http put request is when you're updating data so for example updating the name of a user in a database would be considered a put this corresponds with the update in the crowd and finally an http delete request is when you're deleting data so deleting your account from a website or say deleting a tweet from twitter would be an example of a delete request this corresponds to the delete in crud whenever you make an http request a status code gets returned these are the five major types of status codes one xx would be informational two xx would be success three xx will be redirection four xx will be a client error and 5xx is generally a server error so like i said before we'll be creating this api using spring boot maven jpa and mysql so in case you're not familiar springboot is an open source java based framework used to create a microservice or any kind of service maven is a build automation tool used primarily for java projects maven can also do other things like run automated tests package our app in a jar or war file so we can deploy to any server and also maven gets all of our dependencies that will need like bring boo jpa et cetera jpa stands for java persistence api it's a collection of classes and methods to persistently store data in a database jpa is great because it saves us from writing some boilerplate code that we usually have to write because jpa can do things like create tables for us and columns automatically lastly mysql is an open source relational database management system used to manage databases the mysql client i'll be using personally is my sql workbench i've also included a link to this in the description if you'd like to use it as well so now that all the background is out of the way let's actually get started in writing our first restful api go ahead and open any browser and browse to start.spring.io this is a spring initializer spring initializer generates a spring boot project for you without you having to do anything so prior to actually generating a project you'll be able to do things like add dependencies so let's go ahead and configure our project so at the top keep maven project selected keep java selected for the language and for the spring boot version you want to keep whatever version is selected by default now let's move on to the project metadata for the group name i'm going to type com.johnson.app you can name this whatever you'd like i'm using johnson for my last name but it's mainly up to you for artifact i'm just going to call it rest then for the name i'm just going to say rest api and then for the description i'll just say sample crowd rest api we can leave the package name as is we can leave the packaging as is we'll keep it as jar the version of java you need is eight so select eight now we can add our dependencies go ahead and search for web add spring web and that is all we need for now you can go ahead and generate your project once it's generated you can unzip the folder now once the folder is unzipped you can go ahead and open up your favorite ide we can close out of chrome now i'm going to go ahead and open up intellij next i'm going to import a project select import project now browse for that extracted folder next we want to keep it as import project from external model select maven click next click next again we'll keep all the defaults next next and then click finish so now we have our first spring boot project actually generated let's go ahead and expand the folder in our package you see we have a rest api application class let's go ahead and open that in here we have a very simple class within the class we have our main method and then within that main method we're calling one function we're also annotating this class with the spring boot application annotation so this annotation is basically telling the ide that this is indeed a spring boot app it's that simple guy spring boot makes things very easy for us let's go ahead and open up the palm.xml file the palm xml files where maven puts all of their dependencies as you see we have dependency section and then within that we have each dependency so we don't need to know too much about this guys i'm going to be doing a maven tutorial in the future so stay tuned for that but for now just know that this is where maven keeps the dependencies and other metadata go ahead and exit that out and let's run this to see what happens in the console we get started rest api application in 1.472 seconds and then above that we can see that tomcat has started on port 8080. basically tomcat is just an app server that you can deploy applications to so let's go ahead and open up our browser again and browse to localhost colon 8080. so as you see we get this error that says white label error page this might look like it's bad but this is actually great that means spring boot is indeed running so we're seeing this error basically because we don't have a get endpoint there's nothing to really show so this is just a default error that spring boot provides for us because we don't have a slash error mapping so let's go ahead and go back to intellij and let's create our first actual endpoint i'm going to create a new package called controller a new class called api controllers within that let's create a new method called get page okay so this method has a return type of string and it's called get page now in this method let's just return welcome okay we have a very simple method okay so now let's annotate this class with the annotation called rest controller make sure you guys import that from the spring framework that tells the ide that this class is indeed a rest controller and that we're going to have some type of endpoints in here now let's go ahead and annotate the method with at get mapping after that add some parentheses and we can add a value here for the actual endpoint that we'd like let's go ahead and just set it to a forward slash the forward slash is the default endpoint that gets hit when accessing an application like when we hit localhost 8080 by default it hits the forward slash so now we have a value of forward slash now let's go ahead and run this and see what happens so in the console we see that our app has started on port 8080 once again now let's go back to the browser and see what's different let's refresh this and as you see we see welcome congrats guys so basically we really do have our first api created but it's not a crud api just yet because we're not creating or updating or deleting anything just yet we're just really reading and all we're reading is welcome we're not reading from the database we're not really doing anything fancy all we're doing is returning welcome but as you see guys it is indeed working so far now let's go back to intellij let's create a new package called models so within that new package right click and create a class called user so moving forward this user object is what will be creating reading deleting and updating so now let's go ahead and add some attributes to this user class okay so now we have our attributes created so user will have an id a first name a last name an age and an occupation so this id attribute is actually going to act as a primary key in the database all right now let's generate some gutters and setters okay great now we have all of our getters and setters generated okay guys now let's go ahead and go to our palm and add the dependencies for jpa in mysql okay guys as you see we have our two new dependencies we have a dependency for jpa and a dependency for mysql great okay now let's go back to our user class and add some annotations to it we have an entity annotation at the top that tells mysql that this user class will indeed be a table within the database so for the id attribute we have id and generated value annotated this tells my sql that id will be unique for each user next we have column annotated for each value that tells my sql that each one of those attributes will be a column in the database so now let's go back and create another package called repo next you want to create a new interface within that package right click go to new select class and then in the drop down change it to interface call this interface user repo next within that repo we want to extend the jpa repository next we want to pass in the brackets a user and a long awesome and that's all we need to do to this class now let's go ahead and open up the resources folder and browse to your applications.properties file so the application.properties file is the file that spring looks for when doing configurations or setting various properties so we can even set things like the port that we want to deploy to whenever we run this application so we can set something like server.port equals 9000 let's go ahead and try that so if i were to run this application instead of deploying to localhost 8080 when we run it would actually use port 9000. so this is an example of something that we can do within a properties file so let's go ahead and delete this because we actually don't want that now i'm going to add some properties for our database connection okay so now i have the database properties first we have a url for our database the name of the schema that we'll be using is crud users will create that after this and then i'm using the default root username as well as my password when you first installed my sql workbench you should have created a root username as well with a password so just use yours okay so now you want to save that and open up my sql workbench so within mysql workbench you want to click the plus next to my sql connections and create your first connection let's name this restful api as you see in the username we have root and then we're going to use our password so now let's hit test connection at the bottom and enter your password awesome it says successfully made the mysql connection great that's exactly what we wanted so now click ok and then click ok and get out of here now you want to open up that connection that we just created restful api now on this left hand side in the schema section you want to right click and click create schema now we're going to name this schema exactly what we named it here crowd users click apply click apply again now we're all set we have crud users created awesome now let's go ahead and go back to intellij let's run our application awesome everything worked as expected so now we have the project started up on port 8080 once again now let's actually go back to my sql workbench expand the crowded users schema and as you see we have a users table generated if you don't see a user's table try right clicking on the crud user schema and refreshing let's right click on users and just do select rows as you see we have an id age first name last name and occupation column these are all of the properties from our model as you see we never had to create the table by hand or the columns itself this is awesome this saves us so much time so now let's actually persist some of these users let's actually save some users to the database get some users from the database update some users and delete them so now let's go back to our controller package and open up api controller so now what we want to do is inject our repository now you want to annotate that declaration with auto wire basically the auto wired annotation handles all dependency injection for us now let's create a new method so now we have a new method called get users of type void so what's great about the jpa database is it comes with a whole bunch of pre-built methods some of the methods are things like getting a list of your object from the database getting an individual object from the database updating an object in the database deleting an object in the database and so on so let's go ahead and return one of those methods in our get users function so we're going to return this user repo dot find all what this will do is return all of our users from the database so let's change our return type to actually be a list of users import that list now next we need to annotate our method with get mapping let's give it a value of users let's save this and run it and see what happens okay so as you see we browse to localhost 8080 we still get welcome now let's force slash and go to users as you see we get an empty array this is because we don't have any users in the database but we actually see that this endpoint is indeed working great so now go back to the code now let's actually create a function for saving a user now we'll utilize another one of the repo functions this function will take in an object of type user next we want to annotate this method with post mapping because this is a post method remember whenever we're saving something to the database it'll be a post let's give it a value of save next we need to annotate our user parameter with at request body because this is what will get sent through the requests using json we're going to send a user through json next we need to annotate our user parameter with at request body because what will get sent through the request in the body is an actual user object the user object will be written in json since we don't have a user interface to actually submit this user to save we're gonna have to use another client there's a whole bunch of other clients you can use or json tools that you can test post and puts and delete we're going to go ahead and use a tool called postman i'll provide a link in the description box so you guys can check out postman and use that and what we want to do is utilize another function on the repo so now we're calling the save method on the repo and then we're going to pass in that new user and save it to the database the jpa repo handles all of this and will actually save it to the database without us having to type any other things after we do that let's just go ahead and say something like save awesome so once you have postman downloaded go ahead and open that okay so now that we have postman open click new in the top left corner click request and let's name this api get then click save now let's test our existing get endpoint to get a list of users now click send and as you see we get our empty list in the response body great this is exactly what we wanted now let's go ahead and test our new save endpoint create a new request and let's name this api post click save now let's change this to a post and for the url enter our new endpoint we created now select body then go to raw then change this from text to json now let's create our user object okay so now we have our user object we're going to save john doe to the database he has an age of 25 and he's a developer of course okay now let's go ahead and send this request to the server and see what happens as you see we get saved we get saved because this is exactly what we put as the return in our controller now let's go back to postman let's do the request to get a list of our users again to see if that did indeed save so now we're back at our get request now let's send this again and as you see in the output we indeed get our john doe user that we just saved awesome now we see that we are actually persisting data in our app now let's check the database to see if it's saved there as well open up mysql workbench now let's do a select from the table and see what happens as you see we do get the john doe user in here okay so now let's move on to the update functionality of our api okay so we're in our controllers class what you want to do is create a new method we're going to call it update user then we're going to annotate it with request body now let's annotate this method with put mapping let's give it a value of update then a forward slash with the user id so now since we're passing in the id in the url we need to also take in that parameter in the function okay so now we're taking in an id of long to the function now we need to annotate that id with the annotation of path variable now within our method body let's actually find that user we can find the user by using another function on the user repo okay so we're going to call this find by id method on the user repo and pass in the id that was in the path then we're going to call this get function on that to actually get the user now let's set the user attributes from the parameter to the updated user we just created now let's call that save method on the user repo again to save this user now let's just return something that says something like updated now let's rerun our app okay so there were no issues now let's go ahead and go back to postman to create a new request click new let's name this request api put now let's change it from get to put and put in our newly created endpoint okay so now in the url we're putting in localhost 8080 forward slash update forward slash one we're putting one because the user that's currently in the database has an id of one the id we put in the url will be the user that gets updated okay so now let's select body go to raw then change it from text to json okay now let's go ahead and copy our user from our post request let's paste that in the put request and let's change something let's change them from developer to a senior developer now let's send this as you see we get updated now let's call our get request again and see if it actually updates john doe awesome so now john doe is a senior developer so now we currently have a get request a post request and a put request all working so now we have the c working and crud the r working in crud the u working in crud and now we just have to work on d finally so let's go back to intellij okay now let's create a new function and let's call it something like delete user okay so this function will take in another long path variable of id we're going to annotate this class with delete mapping and let's give it a value of forward slash delete then the id okay so now let's call that find by id method on the user repo to get the user now let's call the delete method on that user repo okay so we're calling the delete method on the user repo and we're passing in the user that we want to delete now let's go ahead and return something like deleted user with id then id now let's rerun the app okay so now let's go back to postman and create a new request go to new in the top left let's call it api delete now let's change this from a get to a delete and pass in your newly created endpoint okay so we're passing in localhost 8080 for slash delete forward slash the id we want to delete okay so let's go ahead and send this and see if it works okay now we get deleted user with the id one let's go back to our get request and see if it actually deleted awesome so we no longer have any users in the database our delete functionality is indeed working so awesome guys we have a get working a post working a put working and a delete so congrats guys you guys have really created your first fully functioning crud restful api awesome guys congrats i hope you guys enjoyed this video and remember subscribe to the channel guys it helps me out a lot and remember to like the video alrighty have a good one guys have a great rest of your day i'm out of here seeing in the next video peace

Channel: Maurice Johnson

Views: 5,618

Keywords: java, mysql, spring framework, spring boot, rest, restful, api, application programming interface, crud, postman, jpa, maven, computer science, software engineering, programming, coding, software, engineer, sql

Id: YVl6M5ztOu8

Length: 18min 38sec (1118 seconds)

Published: Tue Sep 29 2020

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