Fast API Tutorial, Part 3: Query Parameters

hello everyone and welcome to the third video in our fast api tutorial series uh in this video we are going to be talking about query parameters as i mentioned in the last video uh query parameters are just um any sort of extra little tags you want to put at the end of your um your url um they allow for you know a little bit more dynamic uh searching uh from the front end if you will so let's go back into our our running app that we have here we're gonna modify the oh no i don't have user i don't have items anymore so let's create an items route so we're going to do app.get items and we're going to say async def get items or i think i called it before list items now the way we had it set up before if you had a path parameter that you declared here you then had to declare it here and it would know to look for the path parameter a query parameter is an item that you're including in your function parameters that is not otherwise listed up here that's it so if we were to add in skip we're going to call it an integer we're going to by default set it equal to 0 and limit integer and we're going to set it equal to 10. for this we're going to also let's just create a fake items database item name foo and we'll do a couple more of these we'll call this one bar and that one bass okay now we're going to return our fake items database starting at skip and going to skip plus limit and that's it that's how we set up a set of query parameters so if we go into here items is just going to return everything because by default we're saying that the this integer is going to be 0 so we're not going to skip anything and by default this limit is going to be 10. what is this saying oh and watch i save it black is going to yell at me yeah whatever it's fine so if we were to add in something like skip equals 2 then it would only return the last item if we were to return limit or do a query parameter limit equals 1 it will return the first item we go into here and we hit refresh and we can see list items and it doesn't give us any parameter here it doesn't actually let us know that there are query parameters but you know you're just going to end up having to open it up and find out we can do the same thing that we did before because it's a get request so we can do limit of two we're going to get foo and bar if we start at skip of one we would get bar and bass okay so that's just a basic introduction to query parameters now if we want to make some of these parameters optional what we can do let's do app.get items item id async def get item item id is a string and the query is going to be a string and let's do optional string equals none and for this we need to from typing import optional so now what we're going to do is we're going to say if the query so if it's not none we're going to return item id is the item id and the query is the query otherwise we're just going to return item id is item id so this actually gets into um when you want to have path and query parameters so you can see here we've got item id and q so fast api will know that item id is actually going to be a path parameter because we've declared it up here it's going to know that q is a query parameter because we're declaring it as a primitive type we'll get into um request body in the next video um but if you pass something in that's going to be a string or an integer or a float boolean something like that then it's going to be a query parameter the other thing that we can do is if you're using python 3.10 you don't have to use this optional notation anymore you can just use str or none equals none and then we can get rid of optional here so now if we refresh the page let's close this up let's open this so we have this item id which is required we're going to say [Music] hello we're going to hit execute and it only returned the item id of hello if we passed in a query let's do world and we hit this then we get the item id is hello and the query is world so it ended up going into this one it's that simple um it's really not terribly difficult to include um optional uh um optional query parameters okay um the next thing that we're gonna touch on is type conversion we're using pedantic so let's see a neat little trick that we can that we can include here so what we're going to do is we're going to add in an extra field short we're going to call it a boolean and by default it's going to be false okay what we want to do here now is we're going to declare item equals item id item id now what we're going to do here is we're instead going to say item.update and we're just going to update with the query if we have a query we're going to update with the query and then what we're going to do down here is if not short item dot update description and let's see can i do lorem 10 no it doesn't like it that's one downside to uh pie charm more of ipsum let's go here let's get 10 words there we go okay so if we're saying short is not true then we're gonna update the item with this description and then we're just gonna simply return the item okay now we go back into here and we refresh this page and you can see we have now our item id is again hello we will again say world for this and short can be either a boolean it can be either true or false it's a boolean so we pass this in we see we didn't pass in anything so by default it's assuming it's false if we want to pass in this then it works if we want to pass in this then it works that's nothing interesting the thing that is interesting is if we're using it here in the url bar not if we're using it here no one really cares about this this is just for testing what we care about is using it if we're fetching from a client-side app so what we can do here if we do items and then we're going to slash hello and then we're going to say query equals world and then we're also going to say short equals one so what what pydantic did is it did type conversion of this integer value if we did short equals zero i don't care about that then it returns the long version with the lower mipsum so that's another nice thing about pedantic and about this the setup that we have is it will be converted so we can replace it with true we can replace it with lowercase true we can replace it with on or we can replace it with yes and all of those will work assuming that those those convert into a situation where true where short equals true if we type in no then we get that value down there or we could just pretty much get rid of it and we get the same thing okay so that's pretty much it for uh for query parameters i mean there are a few other things that we can do um we can add in if we want to do app.get we'll say users user id items item id we can have multiple path and query parameters async def get user item we'll say user id is an int item id is a string query is a string or none which is none and short is a boolean which i'm going to leave it like this and it's going to yell at me we're going to see a non-default parameter follow the default parameter but let's just do item equals item id item id owner id user id and then if query again we're going to update query is query if not short and then we'll just come up here we'll return this whole thing again i don't care about that go into the terminal and we can see we got the error here that we should have gotten that we should have addressed up here that's one other thing this is just a this is not a fast api sort of situation this is just a generic python situation we're declaring a default parameter here you can't have non-default parameters after default parameters in your function declaration so we're going to just declare that here and everything should be fine so we do this again we refresh this page and we can see here we get all of these items here um these path parameters are required uh the query is not required we'll say one two three four five six that can be a string that's fine and we're good okay um i think that's pretty much it we have the ability to i'll just add one more thing here app.get um actually let me just see if it's up here yeah i'll just add this one really quickly um sample query param we'll call it a string and then we will say sample query param uh this will just demonstrate that you can have um required uh query parameters it's kind of a weird thing if you think about it um if you want something to be required then you should just in my mind you should just include it as a path parameter but you can include uh required query parameters so if we were to type in one two three hello and we will make short true we return this and you can see we get that the request that it actually submitted was this one here so we'll copy this we'll paste it here and let's get rid of sample query param just to see what happens and you can see we got field required the sample query parameter variable was required okay so now really i think that's it it's about almost 14 minutes now so in the next video we are going to touch on request body like i mentioned we have path parameters done we've done query parameters now we're going to get into the idea of submitting a post request and sending data via post put you know something like that where it's not going to be in the url but we're going to actually pass data back to the server okay see in the next video

Channel: JVP Design

Views: 25,561

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Id: f3CyAmelnEY

Length: 14min 10sec (850 seconds)

Published: Tue May 03 2022