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Reqparse9:15 with Kenneth Love
With resources defined and everything connected with Blueprints, it's time to handle incoming arguments. Flask-RESTful provides a solid tool known as Reqparse for specifying and validating submitted data.
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Our resources are ready for action, but they don't yet 0:00 know how to take in input from our users. 0:03 We need some way of telling them what pieces of data they should expect, 0:05 like a title and URL for the courses, and also what those pieces of data should be. 0:08 Title should be strings, for example. 0:13 If we were doing this with models and 0:16 views, we'd use a form or some other sort of validation library. 0:17 Flask restful actually provides a validation library for 0:21 us that works really well, it's called reqparse, and it's for 0:24 parsing requests, let's go see how to use it. 0:27 So once I get reqparse set up, 0:31 I'm gonna be using Postman to test the API that I'm building. 0:33 This is a good time for you to go and get it installed though, there is both 0:37 a Chrome app and an OS X app, both are free and work more or less the same way. 0:40 I'll put a link to their site in the teachers notes. 0:45 I'm going to go ahead and put in the Chrome app though, because, 0:48 you know, I'm running Chrome. 0:51 And the cool thing is, 0:52 it pops up here in your little bar and then you hit Postman and there's Postman, 0:56 so cool, I'm going to skip that go straight to the app. 1:02 Reqparse tells the API how to parse incoming requests. 1:06 If you've used the Python module arg pars it's pretty similar so 1:10 what I wanna do this over here and courses.py, I need to import reqparse. 1:15 And then, I'm gonna add a parser to the course list thing here 1:25 first of the course list resource. 1:29 I don't know why I call it a thing, it's just a thing today. 1:31 All right, so, inside init, we're gonna do self.reqparse 1:34 = reqparse.RequestParser, 1:40 sometimes you just can't predict the variable names. 1:45 And so self.reqparse.add_argument, so we add arguments to 1:49 the parser for each of the things that we want to have come in each of the fields. 1:55 So for courses, I want to have one for title, I wanna have one for URL. 2:01 So let's add title first. 2:05 It is true, it is required, you have to have it. 2:09 If you don't give it to me, I'm going to say, no course title provided. 2:12 I could just say, no title provided, but either way. 2:16 And then location is actually going to be a list, it's going to be form and json. 2:20 So what this says is that, I need to tell reqparse where to look for this data. 2:26 So, I'm telling it to look in forming coded data or 2:34 to look in json data, which is in the body of the request. 2:37 Whichever one comes last is the one that's looked at first, 2:41 it's a little weird, but that's the way that one works. 2:45 All right so let's add the other argument here, self.reqparse.add_argument, 2:49 you can probably guess how most of this goes. 2:54 It's going to be url, required=true, 2:57 help=No course URL provided, 3:02 and location is gonna equal form, and json. 3:07 There are lots of other locations, I will link 3:11 to that documentation in the teacher's notes, so you can check that out. 3:14 Everything here is fairly straightforward, this is very similar to a forms library, 3:18 where you're kinda specifying what all this stuff is. 3:22 And by the way, if you're familiar with REST you might be thinking form here is 3:26 form data and it's not it's the X dash dab dab dash form URL link encoded 3:32 header which is like the standard one that HTML forms send. 3:38 So the basically the idea here is you can send a form to your API and 3:43 it'll work just like you were sending an XHR request or something like that. 3:46 And then at the end here, I do want to go ahead and 3:50 call super, and call init on that. 3:56 All right, so there we go. 4:00 This just makes sure that the standard set up goes ahead and it happens. 4:04 Let's look over here at Postman, now the cool thing is you can you see this 4:08 history thing you can save your post and stuff, which is kinda neat. 4:12 So, let's come over here and 4:16 get the URL, which is that one, all right. 4:20 If I do a get to courses and send, then I get back Json. 4:25 That's cool, that's exactly what we expected to get. 4:33 Okay, so let's try and do just a blank post to 4:35 it and I get back method is not allowed for this requested URL. 4:41 You know what I forgot all about that, I didn't add a post, did I? 4:46 All right let's go, we've got to get, let's add a post. 4:49 All right it's a def post(self), all right, and 4:53 then let's actually break apart these arguments. 4:58 So args=self.reqparse .parse_args, 5:02 I dare you to say that line like five times fast. 5:06 And we're gonna return jsonify, you know what, we're gonna return. 5:11 We're gonna return nothing. 5:17 Okay, so we get the same response back on get or post but 5:20 on post it parses these args. 5:23 All right, so now, 5:25 I should be able to post it because the method's allowed now, I should have it. 5:27 So let's hit send and no course title provided, that's right, 5:31 I didn't provide a course title. 5:37 And if you look here, you can see the status is a 400 bad request. 5:39 So good, that's what i should get because it is a bad request, 5:43 it doesn't have all of the right data. 5:46 All right so let's come over to body and let's say raw and 5:49 then we're going to put in title is Python Collections. 5:54 Okay, so we're just gonna send that, that's all we're gonna send. 5:59 Can I change, yeah. 6:04 So JSON application JSON, okay, so send. 6:06 And what did I get here, I got No course URL provided, 6:11 which is also true, I did not provide a URL. 6:17 All right, now, let's say URL and 6:20 i'm just gonna send python-collections because I'm just playing with this, 6:23 I don't know what I'm doing. 6:29 Let's send that, and I get back the data. 6:30 Wow, okay, so I got back a 200, 6:36 everything's okay, and I got back the data. 6:41 This isn't what I wanted to get though, because python-collections, 6:43 right here, that's not a valid URL. 6:47 So we need to make the parsers smarter. 6:50 Okay flask REST will come with a bunch of predefined inputs, 6:52 you can make your own but you often probably don't have to though. 6:56 The one that I need is included, so I'm going to use it. 7:00 So I'm gonna come up here to reqparse and I'm also import inputs, 7:03 going to have a lot of imports here from restful. 7:09 So, now title here by default these are always strings so 7:13 I don't need to add anything there. 7:16 So here on add argument, I'm going to add a new argument to the argument and I'm 7:18 gonna be type and I am going to put the type is a URL and it comes from inputs. 7:23 So now let's see what happens when I try to post a bad URL. 7:30 So I hit send, and now I've got the 400, and the no course URL provided. 7:35 Great, because that's true, I did not send a URL. 7:40 All right, so now what if I send an actual valid URL? 7:45 Let's come back over here https://teamtreehouse.com/library/python-- 7:48 collections. 7:55 All right, so send that. 7:56 I have 200 and I got back my courses list. 7:58 So cool, that's the 200 that I expected. 8:02 I want to add one more part, I wanna actually save the model instance. 8:05 I'm not going to about changing the output though. 8:08 Because that's just a lot of trouble for right now and 8:11 we'll deal with that in a minute. 8:13 So I've got models imported already, so that's cool. 8:15 So then down here once I parse the args, 8:18 the args basically become a dictionary of all these items. 8:21 So I'm gonna do is I'm gonna do models.Course.create(**args). 8:25 And that will take the args dictionary and feed all of that data into Course.create. 8:31 So, cool, and now, if I go and submit my thing again, 8:38 still got a 200 and I don't have a way to look at this yet. 8:44 We'll check out the data that's in the database, in the next video. 8:49 For now though, 8:53 I'm gonna add the rest of these request parsers, while you do a code challenge. 8:53 You should try and do the requests parsers yourself too, to both course, 8:57 singular, and to review list and review. 9:01 And in the next video you can compare yours to mine. 9:04 Reqparse handles the request part of the request response cycle, 9:06 we still need to deal with the response half. 9:11 We'll do that in the next video. 9:13
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