Blueprints

Since Flask is a microframework, it often gets used as a single module or 0:00 maybe a model or two and then all of the routes and logic in a single app module. 0:04 This works great until your app gets moderately complex and 0:09 you start having to use your editor search function just to find a particular piece. 0:12 Once you split everything out into separate files, 0:16 you'll likely find that it gets harder and harder to avoid circular imports. 0:18 Or a chain of imports that ends up having one file import another file that 0:22 also imports the first one. 0:26 Flask has a feature named Blueprints, and 0:29 Blueprints give us the ability to make objects that are almost like proxies for 0:31 Flask apps or other features like our API resources. 0:35 Let's hop back into work spaces and get this all wired up with Blueprints. 0:38 Okay so I need to import the Blueprint object from Flask. 0:42 I'm here inside courses.py and so I'm just gonna add Blueprint right there. 0:48 Now this might seem a little bit weird and awkward but just stick with me for 0:53 a minute. 0:57 So I'm gonna to make a blueprint that represents this entire module course.py. 0:58 I'm wanna do this down here at the bottom. 1:04 And I'm gonna say courses_api = Blueprint 1:05 ('esources.courses', which is the path to the file and 1:09 then name which is the namespace that we're in. 1:15 So it's the file all over again. 1:20 So basically this says, okay, treat this file with this namespace and 1:23 this path as being another app, another thing. 1:32 And like it's a proxy to this module that kind of sort of acts like an app. 1:36 It's not an application, this isn't a pluggable app or anything like that. 1:42 It actually kind of acts like a log to some degree. 1:46 Anything that I do to this, 1:49 all the actions that I execute on the blueprint, don't actually happen 1:50 until I register the blueprint with an actual running Flask app. 1:55 I'll show you what I mean with this next step. 1:59 We've got to add a little bit more to this file though. 2:02 So we have to actually make an API. 2:06 And it's weird that the import is capital A lowercase pi, but just whatever. 2:09 Okay, so then we're gonna say api = Api[courses_api]. 2:16 So we're making an API out of the current module, which kind of acts like an app. 2:21 Normally you pass in an app here, okay, you with me so far? 2:28 All right, let's do the next thing here so api.add_resource. 2:32 And resource we're going to add is CourseList. 2:38 And we're going to set the endpoint to be /api/v1/courses, 2:42 or this is the URL slug rather, and 2:47 then the endpoint we're actually going to call this is courses. 2:49 Okay, and then we're gonna add another one here, api.add_resource. 2:56 And this one goes to Course, and 3:02 again we're going to give it /api/v1/courses. 3:05 And then we're going to say that there's an int argument that we're gonna call id. 3:10 And then this endpoint is going to be course. 3:14 All right. 3:18 So each of these specifies the resource to add, like CourseList. 3:19 The URI to give to that resource. 3:23 And then the endpoint to name it. 3:26 This way we can be like, I want the courses endpoint. 3:27 Now you don't have to provide the endpoint name, 3:30 Flask just lower cases the name of the resource. 3:32 So like this one would become course list and this one would become course. 3:36 You'll probably find yourself wanting simpler import names, 3:40 you don't necessarily want course list as the endpoint name. 3:42 And the name can be used a few different places in Flask RESTful. 3:46 Some of those, we're gonna talk about a little bit later. 3:49 Okay so now I have to register the endpoint with the app, so 3:52 I'm going to pop back over here to app.py. 3:55 And up here after I import models I'm gonna say from resources.courses 3:59 import course.api. 4:04 And then after the app thing here I'm gonna do app.register 4:07 _blueprint (course_api). 4:12 All right, so, Courses_api, and courses_api. 4:16 There we go, okay. 4:29 So I should be able to get a list of my courses. 4:31 So if I go to /api/v1/courses, cool. 4:34 There's my courses and my fake course that's in there. 4:40 All right, so that's awesome. 4:45 There it is. 4:47 Now I'm enforcing the API versioning, the versioning number right here in the URL. 4:47 Right that's what I have the /v1. 4:54 This is pretty common and it's probably the easiest solution. 4:55 This is probably what you'll find yourself doing most of the time. 4:59 And this way you're keeping the resource and the API right next to each other. 5:02 But you can also do this in the blueprint. 5:07 I kinda like that solution a little bit better too. 5:10 It feels a little bit cleaner. 5:12 Let me show you that one for reviews, and 5:14 you can decide which one that you like better. 5:17 So up here at the top, we're gonna import Blueprint. 5:19 And we're gonna import API just like we did before. 5:22 And then down here, reviews_api=Blueprint( 5:27 'resources.reviews, __named__), 5:34 api= Api(reviews_api). 5:40 api.add_resource, and ReviewList and 5:44 I'm just gonna put in /reviews. 5:49 And my endpoint is gonna be reviews. 5:54 And then api.add_resource. 5:56 Review, and here I'm gonna put reviews. 6:00 And then of course again my int:id argument and endpoint = review. 6:05 All right. 6:12 So I didn't put any of the versioning numbers in here. 6:13 So I'm gonna come back over here to app.py and 6:16 from resources.reviews import reviews_api. 6:21 And then here, app.register_blueprint(reviews_api), 6:27 just like before. 6:33 And then we're gonna do this url_prefix='/api/v1'). 6:35 And so this does the same work, but we're doing it where we register 6:41 the blueprint instead of where we create the resource. 6:46 So it's kind of six of one half a dozen of the other. 6:50 So if we go here to reviews, then we get our reviews. 6:52 Now have the same URL pattern, 6:57 but I've defined them in two different ways in two different places. 6:58 Like I said you can pick whichever one of these URI methods that you like better. 7:03 I'll leave them both implemented throughout the course though, so 7:07 that you can see them both multiple times. 7:09 Blueprints actually took me quite a while to figure out. 7:12 They're not 100% intuitive, but once you get the basic ideas of them down you'll be 7:14 able to use them to make your Flask projects cleaner and better organized. 7:18 They open up a whole new world of Flask project design. 7:22