I have a huge application that was getting hard to update its views. To 'fix' this, I had separate the views into a few files, using blueprints. The problem is that the blueprints are also getting very big, because the long documentation that each view has and the different verifications that each view requires.
I had tried to do an import like this:
Where I have a main file that contains the Flask application (which imports the blueprint), a file that contains the blueprint and a file the imports the blueprint and configure the views in it. The problem is that with this approach the views are not rendered, because flow reasons.
The main file, in the root of a folder:
from flask import Flask
from source import test
application = Flask(__name__)
application.register_blueprint(test)
application.run()
The blueprint file, inside a subfolder in the root folder:
from flask import Blueprint
test = Blueprint('test', __name__)
The view file, inside the same subfolder as the blueprint file:
from .test import test
#test.route('/home', methods=['GET', 'POST'])
def home():
return 'home'
I had also tried to add the blueprint decorator to a declared function, this way the views are add to the blueprint in the blueprint file, but I don't think this is a good approach or a scalable approach - and it didn't work ^ - ^.
I expect to create a blueprint in a file, import the blueprint in other files and add views to the blueprint and then import the blueprint and add it to the Flask application.
You need to import the views content in blueprint file.
I have created the scenario and able to get the view. Additionally, I have updated the naming convention.
Folder structure:
.
├── app.py
└── blueprints
├── example_blueprint.py
├── example_views.py
└── __init__.py
app.py:
from flask import Flask
from blueprints.example_blueprint import bp
app = Flask(__name__)
app.register_blueprint(bp)
blueprints/example_blueprint.py:
from flask import Blueprint
bp = Blueprint('bp', __name__,
template_folder='templates')
from .example_views import *
blueprints/example_views.py:
from .example_blueprint import bp
#bp.route('/home', methods=['GET', 'POST'])
def home():
return 'home'
blueprints/__init__.py: Blank file
Output:
Running the application:
export FLASK_APP=app.py
export FLASK_ENV=development
flask run
requirements.txt:
Click==7.0
Flask==1.0.3
itsdangerous==1.1.0
Jinja2==2.10.1
MarkupSafe==1.1.1
pkg-resources==0.0.0
Werkzeug==0.15.4
Reference:
Flask documentation on Blueprints
In root folder change main file:
from flask import Flask
from source.listener import test
application = Flask(__name__)
application.register_blueprint(test)
application.run()
The blueprint file, inside a subfolder in the root folder:
listener.py
from flask import Blueprint
from source.view import home
test = Blueprint('test', __name__)
test.add_url_rule('/home', view_func=home,methods=['GET', 'POST'])
The view file, inside the same subfolder as the blueprint file:
from flask import request
def home():
if request.method == 'POST':
user = request.form['name']
return "Welcome "+user
else:
return 'home'
Get Request O/P:
Home
Post Request O/P:
Welcome username
The view module isn't discovered since only the Blueprint object is imported.
From the organization of your Blueprint and particularly the import that you have shared in your main file, I can deduct the existence of an __init__.py in the blueprint folder that exports the blueprint object.
Importing the views in that file should have the app discover the views registered in the blueprint.
i.e.
blueprint/__init__.py:
from .test import test
from . import views
Related
I'm currently working on learning Flask and create a working page with login functions. Now I want to remove the global app instance and started using blueprints for the submodules.
My project is structured like this:
+ app
+ auth
- __init__.py
- forms.py
- routes.py
+ main
+ models
+ templates
- __init__.py
+ migrations
- index.py
- config.py
No I added a blueprint to the routes.py and used the decorators there:
from flask import render_template, flash, redirect, url_for, request, Blueprint
from app import app, db
from app.auth.forms import LoginForm, RegistrationForm
# ...
from app.models.User import User
blueprint = Blueprint('auth', __name__)
#blueprint.route('/login', methods=['GET', 'POST'])
def login():
return "example login"
The __init__.py of the auth module:
from . import forms, routes
The blueprint gets added in the __init__.py of the app folder:
# ...
app = Flask(__name__)
app.config.from_object(Config)
db = SQLAlchemy(app)
from app.auth.routes import blueprint as auth_bp
app.register_blueprint(auth_bp)
After using the #blueprint decorators, I don't need #app anymore, but how can I access the db when I want to remove the import app and the from app.models.User import User part?
from . import db
from ..models.User import User
There are two things to understand here. app as a module (the folder) and app the instance of flask inside __init__.py. When you do import app inside authentication blueprint then you are actually importing the whole app module and not the flask instance. When you do from app import app you are actually importing flask instance from app module. This can be confusing to eliminate this I advise you to change the name of app folder to something different like bacher then when you need to import db inside your authentication blueprint use from bacher import db and for User model from bacher.models.User import User
Background
I'm trying to set up a blueprint whose name matches the filename it resides in, so that when I reference it in my app.py I know where the blueprint comes from. This should be possible because the example on exploreflask uses the same pattern. Still, I cannot figure out how to make this work with my structure.
File structure
├── app.py
├── frontend
├── __init__.py
└── views
├── home.py
└── __init__.py
Example
frontend/views/home.py
from flask import Blueprint, render_template
home = Blueprint('home', __name__)
home1 = Blueprint('home1', __name__)
frontend/views/__init__.py
from .home import home
from .home import home1
app.py
from flask import Flask
from frontend.views import home
from frontend.views import home1
print (type(home)) --> <class 'function'>
print (type(home1)) --> <class 'flask.blueprints.Blueprint'>
As home1 registers correctly as a Blueprint but home does not I suspect that
there is a name collision but I don't know how to resolve it despite looking into
this excellent article on importing conventions.
As a result, when I try to register my blueprints with the app
this will work:
app.register_blueprint(home1, url_prefix='/home1') --> Fine
but this won't:
app.register_blueprint(home, url_prefix='/home')
--> AttributeError: 'function' object has no attribute 'name'
Why not just go along with using home1?
I want to understand how the collision can be resolved
I want to be able to use route names that are the same as the filename they are in like so:
frontend/views/home.py
from flask import Blueprint, render_template
home = Blueprint('home', __name__)
#home.route('/')
def home():
pass
I think your views/__init__.py file is causing this issue. It's making python assume your home.py file is a module to be imported. I believe the line from frontend.views import home is trying to import the home.py file rather than your intended home.home Blueprint.
Here's a working example:
/app.py
from app import create_app
app = create_app()
if __name__ == '__main__':
app.run()
/app/__init__.py
from flask import Flask
def create_app():
app = Flask(__name__)
from .bp import bp
app.register_blueprint(bp)
return app
/app/bp/__init__.py
from flask import Blueprint
bp = Blueprint('bp', __name__, template_folder='templates')
from . import views
/app/bp/views.py
from app.bp import bp
#bp.route('/helloworld')
def helloworld():
return "hello world"
Try to use Capital letters in the Blueprint Module.
also you can use the url_prefix in the module.
Home = Blueprint("Home", __name__, url_prefix="/home")
#Home.route("/")
def home():
pass
I am taking over a Flask application that has a user module, but does not have a landing page. The structure of the project is:
|-application.py
|-manage.py
|-settings.py
|-/templates
|----base.html
|----index.html
|----navbar.html
|----/user
|--------views.py
application.py:
from flask import Flask
....
def create_app(**config_overrides):
app = Flask(__name__)
app.config.from_pyfile('settings.py')
app.config.update(config_overrides)
db.init_app(app)
from user.views import user_app
app.register_blueprint(user_app)
return app
user/views.py:
from flask import Blueprint, render_template, request, redirect, session, url_for, abort
...
user_app = Blueprint('user_app', __name__)
#user_app.route('login', methods = ('GET','POST'))
def login():
....
I placed index.html in the templates folder.
Should I place a view.py in the root directory where I would put a route to an index.html?
You can add additional routes anywhere you want.
However, since the package uses a create_app() app factory, you can't register those routes with an #app.route() decorator; the app is not created in a way you can just import.
So yes, creating a views.py module is a good organisational idea, but do create a Blueprint() there too, and register that blueprint in the create_app() function with the Flask() app instance.
In views.py:
from flask import Blueprint
bp = Blueprint('main', __name__)
#main.route('/')
def index():
# produce a landing page
and in create_app() in application.py, add
import views
app.register_blueprint(views.bp)
(I use a convention of using the bp variable name for all my blueprints, and then just importing the module and registering the module.bp attribute).
It's the explicit import and app.register_blueprint() call that ties any of the blueprints used in a Flask project into the final app's routes. Blueprints can share the same prefix, including having no prefix.
One thing to note: here the views module is now a top-level module next to application.py. It'd be better if everything was moved into a package, giving you more freedom over what names you use. All modules in a single package are namespaced, kept separate from other top-level modules such as json and time and flask, so there won't be clashes when you want to use the same name for one of the additional modules in your project.
You'd move everything but manage.py into a subdirectory, with a project-appropriate name, and move application.py to __init__.py. Imports can then use from . import ... to import from the current package, etc.
I'm learning Blueprints for Flask, but I am having trouble with importing the correct modules. This is my setup:
Folder structure:
- app.py
templates/
nomad/
- __init__.py
- nomad.py
app.py
from flask import Flask
from nomad.nomad import nblueprint
app = Flask(__name__)
app.register_blueprint(nblueprint)
nomad.py
from flask import render_template, Blueprint, abort
from app import app
nblueprint = Blueprint('nblueprint', __name__, template_folder='templates')
# Routes for this blueprint
#app.route ....
__init__.py is empty
The error I'm getting: ImportError: cannot import name nblueprint. I know my import statement is probably wrong, but what should it be and why?
EDIT:
If I remove from app import app, then I can successfully import nblueprint in app.py. But I need app in nomad.py because it needs to handle routes. Why is that line causing issues with importing, and how would I get around this?
Blueprints is for define application route so you don't need to use app instance and blueprint in same place for route defination.
#nomad.py
#nblueprint.route('/')
You are getting error because while you register the blueprint at the same time you use app instance. So as you said when you remove the from app ... it solve the problem.
The recommend way is define your view for that blueprint in blueprint package in your example nomad package, it should be like this:
...
nomad/
__init__.py
views.py
#nomad/__init__.py
nblueprint = Blueprint(...)
#nomad/views.py
from . import nblueprint
#nblueprint.route('/')
...
Lets say I want to build a project Facebook
I need a project structure like
facebook/
__init__.py
feed/
__init__.py
models.py
business.py
views.py
chat/
__init__.py
models.py
business.py
views.py
games/
__init__.py
models.py
business.py
views.py
common/
common.py
runserver.py
How can I structure this well so that when I run
python facebook/runserver.py
It loads views from all my apps internally?
I want to keep this structure because extending the project further is more natural way
I am trying to follow their advice, but don't really understand where I need to write
from flask import Flask
app = Flask(__name__)
and how to import all views from all apps at one place, please help
If lets say I write the above code in facebook/__init__.py, then how in facebook/feed/views.py, I can do
from facebook import app
Use blueprints. Each one of your sub-applications should be a blueprint, and you load every one of them inside your main init file.
Answering your second question
from flask import Flask
app = Flask(__name__)
You should put this into facebook/__init__.py
BTW, my runserver.py and settings.py always resides one level under facebook/.
Like this:
facebook/
__init__.py
feed/
__init__.py
models.py
business.py
views.py
chat/
__init__.py
models.py
business.py
views.py
games/
__init__.py
models.py
business.py
views.py
common/
common.py
runserver.py
settings.py
Content of runserver.py:
from facebook import app
app.run()
I suppose the content of settings.py should not be explained.
Content of facebook/__init__.py:
from flask import Flask
app = Flask(__name__)
app.config.from_object('settings')
from blog.views import blog #blog is blueprint, I prefer to init them inside views.py file
app.register_blueprint(blog,url_prefix="/blog")
I have tried blueprints and came up with a solution which works for me, let me know if you have other ideas.
Project Structure
facebook/
runserver.py
feed/
__init__.py
views.py
chat/
__init__.py
views.py
Code
# create blueprint in feed/__init__.py
from flask import Blueprint
feed = Blueprint('feed', __name__)
import views
# create blueprint in chat/__init__.py
from flask import Blueprint
chat = Blueprint('chat', __name__)
import views
# add views (endpoints) in feed/views.py
from . import feed
#feed.route('/feed')
def feed():
return 'feed'
# add views (endpoints) in chat/views.py
from . import chat
#chat.route('/chat')
def chat():
return 'chat'
# register blueprint and start flask app
from flask import Flask
from feed import feed
from chat import chat
app = Flask(__name__)
app.register_blueprint(feed)
app.register_blueprint(chat)
app.run(debug=True)
In Action
* Running on http://127.0.0.1:5000/
# Hit Urls
http://127.0.0.1:5000/feed # output feed
http://127.0.0.1:5000/chat # output chat