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How to append a prefix to a flask blueprint that already has a blueprint? [duplicate]

I'm still new to Flask, so there may be an obvious way to accomplish this, but I haven't been able to figure it out so far from the documentation. My app is divided into several mostly disparate parts that share things like users/sessions/security and base template and everything but mostly do not interact much, and should be routed under different paths like /part1/.... I think this is pretty much exactly what blueprints are for. But what if I need to group routes and logic further under a blueprint?
For example, I have blueprint1 with url_prefix='/blueprint1' and maybe under that I want to have a collection of views revolving around a user sharing photos and other users commenting on them. I can't think of a better way of doing it than:
# app/blueprints/blueprint1/__init__.py
blueprint1 = Blueprint('blueprint1', __name__, template_folder='blueprint1')
#blueprint1.route('/photos')
def photos_index():
return render_template('photos/index.html')
#blueprint.route('/photos/<int:photo_id>')
def photos_show(photo_id):
photo = get_a_photo_object(photo_id)
return render_template('photos/show.html', photo=photo)
#blueprint.route('/photos', methods=['POST'])
def photos_post():
...
The problem here is that all the views related to the photos section of blueprint1 are located at the "top level," right with maybe blueprints for videos or audio or whatever (named videos_index()...). Is there any way to group them in a more hierarchical manner, like how the templates go under the 'blueprint1/photos' sub-directory? Of course I can put all the photo views in their own module to keep them organized separately, but what if I want to change the parent 'blueprint1/photos' path to something else? I'm sure I can invent a function or decorator that groups related routes under the same root path, but then I still have to name all the functions with the photos_ prefix and reference them like url_for('blueprint1.photos_show') It seems like blueprints are the answer when a Flask app gets large and you need to group and compartmentalize similar parts together, but you cannot do the same thing when the blueprints themselves get large.
For reference, in Laravel you can group related "views" under a Controller class where the views are methods. Controllers can reside in hierarchical namespaces like app\Http\Controllers\Blueprint1\Photocontroller, routes can be grouped together like
Route::group(['prefix' => 'blueprint1'], function() {
Route::group(['prefix' => 'photos'], function() {
Route::get('/', ['as' => 'blueprint.photos.index', 'uses' => 'ModelApiController#index']);
Route::post('/', ['as' => 'blueprint.photos.store', 'uses' => 'ModelApiController#store']);
Route::get('/{id}', ['as' => 'blueprint.photos.get', 'uses' => 'ModelApiController#get'])
->where('id', '[0-9]+');
});
});
and routes can be gotten like action('Blueprint1\PhotoController#index').
If only I could make a photos blueprint, then just do blueprint1.register_blueprint(photos_blueprint, url_prefix='/photos') or the like, these problems would pretty much be solved. Unfortunately Flask does not seem to support nesting blueprints like this. Is there an alternative way to handle this problem?

UPDATE
Flask 2 was released with support for nested blueprints.
[ START: Part from the docs ]
Nesting Blueprints
It is possible to register a blueprint on another blueprint.
parent = Blueprint('parent', __name__, url_prefix='/parent')
child = Blueprint('child', __name__, url_prefix='/child')
parent.register_blueprint(child)
app.register_blueprint(parent)
The child blueprint will gain the parent’s name as a prefix to its name, and child URLs will be prefixed with the parent’s URL prefix.
url_for('parent.child.create')
/parent/child/create
Blueprint-specific before request functions, etc. registered with the parent will trigger for the child. If a child does not have an error handler that can handle a given exception, the parent’s will be tried.
[ END: Part from the docs ]
Source: https://flask.palletsprojects.com/en/2.0.x/blueprints/#nesting-blueprints
OLD ANSWER
My hacky work around is that I made a class called ParentBP that has the following code
from typing import List
from flask import Blueprint
class ParentBP(object):
name: str
url_prefix: str
subdomain: str
blueprints: List[Blueprint]
def __init__(self, name="", url_prefix="", subdomain="") -> None:
self.name = name
self.url_prefix = url_prefix
self.subdomain = subdomain
self.blueprints = []
def register_blueprint(self, bp: Blueprint) -> None:
bp.name = self.name + "-" + bp.name
bp.url_prefix = self.url_prefix + (bp.url_prefix or "")
if self.subdomain:
bp.subdomain = self.subdomain
self.blueprints.append(bp)
so you can call it similar to a blueprint like below
blueprint1 = Blueprint("blueprint1", __name__)
blueprint2 = Blueprint("blueprint2", __name__, url_prefix="/bp2")
api_v1 = ParentBP("api-v1", url_prefix="/api/v1")
api_v1.register_blueprint(blueprint1)
api_v1.register_blueprint(blueprint)
to make the interface similar to normal registering of blueprints to the flask app, I extended the Flask class as follows
class ExtendedFlask(Flask):
def register_blueprint(self, blueprint: Union[Blueprint, ParentBP], **options: Any) -> None:
if isinstance(blueprint, ParentBP):
for bp in blueprint.blueprints:
super().register_blueprint(bp, **options)
else:
return super().register_blueprint(blueprint, **options)
now you can normally do the following
app = ExtendedFlask(__name__)
app.register_blueprint(api_v1)

Unfortunately, nested blueprints are not a current feature in Flask. You'll have to do it manually. You could probably code something that works for your specific case, but a general solution has not been added to Flask. There has been some discussion on the issue tracker:
https://github.com/mitsuhiko/flask/issues/593
https://github.com/mitsuhiko/flask/issues/1548
https://github.com/pallets/flask/issues/3215
Adding nestable blueprints into Flask is not as trivial as automatically appending a prefix to routes. There are many other features of blueprints that need to be considered when nesting that make a general implementation significantly more complicated. The reason this has not been implemented yet is that no one in the community has had a great enough need for it that wasn't solved by a quick workaround vs contributing a general implementation.

I made a class called NestedBlueprint to hack it.
class NestedBlueprint(object):
def __init__(self, blueprint, prefix):
super(NestedBlueprint, self).__init__()
self.blueprint = blueprint
self.prefix = '/' + prefix
def route(self, rule, **options):
rule = self.prefix + rule
return self.blueprint.route(rule, **options)
Here is my base file which contains the blueprint: panel/__init__.py
from flask import Blueprint
panel_blueprint = Blueprint(PREFIX, __name__, url_prefix='/panel')
from . import customize
Here is the specific/nested file which contains nested blueprint: panel/customize.py
from rest.api.panel import panel_blueprint
from rest.api.util.nested_blueprint import NestedBlueprint
nested_blueprint = NestedBlueprint(panel_blueprint, 'customize')
#nested_blueprint.route('/test', methods=['GET'])
def test():
return ':)'
You can then call like this:
$ curl http://localhost:5000/panel/customize/test
:)

Here is my workaround:
When importing a blueprint, I define my nested routes:
app.register_blueprint(product_endpoints, url_prefix='/sites/<int:site_id>/menus/<int:menu_id>/categories/<int:category_id>/products/<int:product_id>')
app.register_blueprint(category_endpoints, url_prefix='/sites/<int:site_id>/menus/<int:menu_id>/categories/<int:category_id>')
app.register_blueprint(menu_endpoints, url_prefix='/sites/<int:site_id>/menus/<int:menu_id>')
app.register_blueprint(site_endpoints, url_prefix='/sites/<int:site_id>')
And inside the blueprints, I'm reusing route parse functions. For example, in the product_endpoints file:
from category_endpoints import get_category_data
product_endpoints = Blueprint('product_endpoints', __name__)
#product_endpoints.url_value_preprocessor
def get_product_data(endpoint, values):
if 'category_id' in values:
get_category_data(endpoint, values)
product = Product.get_by_id(int(values.pop('product_id')))
if not product:
abort(404)
g.product = product
and in category_endpoints file:
from menu_endpoints import get_menu_data
category_endpoints = Blueprint('category_endpoints', __name__)
#category_endpoints.url_value_preprocessor
def get_category_data(endpoint, values):
if 'menu_id' in values:
get_menu_data(endpoint, values)
category = ProductCategory.get_by_id(int(values.pop('category_id')))
if not category:
abort(404)
g.category = category
etc... With that approach, my blueprint is also usable with direct routes like /products/<int:product_id>.
This approach worked for me very well. I hope it can also help you.

Multiple functions on class-based views flask

maybe I'm misunderstanding class-based views on Flask. I come from a PHP/Laravel background. On Laravel I can define a controller class where I can response different json data, views (templates on Flask), etc. So the only thing I do is define a route and associate that route to a specific method on a controller class.
A pseudo-code like this:
On POST associate /path to MyControllerClass#doPostMethod
On GET associate /path to MyControllerClass#someGetMethod
On GET associate /path/extra to MyControllerClass#someOtherGetMethod
...
On Flask I would have them as separated functions. Something like:
def doPostFunction()...
def someGetFunction()...
def someOtherGetFunction()...
So googling a bit, there are class-based views but as I saw it, insted of defining a function I define a class and put the content of the old view function inside dispatch_request class-based view's method.
class DoPostClass(View):
dispatch_request()
...
class DoGetClass(View):
dispatch_request()
...
class DoSomeOtherGetClass(View):
dispatch_request()
...
Is there a way to have these functions inside a single class? am I misunderstading Flask's class-based views? I know there's a MethodView class that has get, post, put, delete methods but as I'm not createing a RESTful API neither I use nice-RESTful urls, MethodView class seems not to be useful for my case.
Thanks in advance.

Based on my laravel/flask project experience, the classy code of controller/view are same. You can try flask-classy extension
Below is an example based on flask-classy.
Directory
.
├── index.py
└── views
├── __init__.py
└── myView.py
myView.py
from flask_classy import FlaskView
class myView(FlaskView):
def index(self):
return "this is index"
def get(self, id):
return "this is page " + str(id)
index.py
from flask import Flask
from views.myView import myView
app = Flask(__name__)
myView.register(app)
Run
$ export FLASK_APP=index.py
$ flask run
# Index: http://127.0.0.1:5000/my
# Get: http://127.0.0.1:5000/my/<id>

Why there is no option to add custom url converters to blueprints like for main app?

In this post and in official docs we saw how to add custom url converters for main app object.
Here is short example:
app = Flask(__name__)
app.url_map.converters['list'] = ListConverter
But how to do it for blueprints? This global (app level) custom converter is unavailable for blueprints.
In source code I haven't found such posibility...

The technical reason why you can't have custom URL converters on a blueprint is that unlike applications, blueprints do not have a URL map.
When you use the blueprint's route decorator or add_url_map() method all the blueprint does is record the intention to call the application versions of these methods later when register_blueprint() is called.
I'm not sure there is a benefit in allowing blueprint specific url converters. But I think it would be reasonable to allow a blueprint to install an app wide converter. That could use the same techniques as other blueprint app-wide handlers, like before_app_request, for example.
def add_app_url_converter(self, name, f):
self.record_once(lambda s: s.app.url_map.converters[name] = f
return f
Blueprint.add_app_url_converter = add_app_url_converter
# ...
bp = Blueprint('mybp', __name__)
bp.add_app_url_converter('list', ListConverter)

blueprint of blueprints (Flask)

I have a series of blueprints I'm using, and I want to be able to bundle them further into a package I can use as seamlessly as possible with any number of other applications. A bundle of blueprints that provides an entire engine to an application. I sort of created my own solution, but it is manual and requires too much effort to be effective. It doesn't seem like an extension, and it is more than one blueprint(several that provide a common functionality).
Is this done? How?
(Application dispatching methods of tying together several programs might work isn't what I'm looking for)

Check this out: Nesting Blueprints → https://flask.palletsprojects.com/en/2.0.x/blueprints/#nesting-blueprints
parent = Blueprint('parent', __name__, url_prefix='/parent')
child = Blueprint('child', __name__, url_prefix='/child')
parent.register_blueprint(child)
app.register_blueprint(parent)

I wish the Blueprint object has a register_blueprint function just as the Flask object does. It would automatically place and registered blueprints under the current Blueprints' url.

The simplest way would be to create a function that takes an instance of a Flask application and registers all your blueprints on it in one go. Something like this:
# sub_site/__init__.py
from .sub_page1 import bp as sb1bp
from .sub_page2 import bp as sb2bp
# ... etc. ...
def register_sub_site(app, url_prefix="/sub-site"):
app.register_blueprint(sb1bp, url_prefix=url_prefix)
app.register_blueprint(sb2bp, url_prefix=url_prefix)
# ... etc. ...
# sub_site/sub_page1.py
from flask import Blueprint
bp = Blueprint("sub_page1", __name__)
#bp.route("/")
def sub_page1_index():
pass
Alternately, you could use something like HipPocket's autoload function (full disclosure: I wrote HipPocket) to simplify the import handling:
# sub_site/__init__.py
from hip_pocket.tasks import autoload
def register_sub_site(app,
url_prefix="/sub-site",
base_import_name="sub_site"):
autoload(app, base_import_name, blueprint_name="bp")
However, as it currently stands you couldn't use the same structure as example #1 (HipPocket assumes you are using packages for each Blueprint). Instead, your layout would look like this:
# sub_site/sub_page1/__init__.py
# This space intentionally left blank
# sub_site/sub_page1/routes.py
from flask import Blueprint
bp = Blueprint("sub_page1", __name__)
#bp.route("/")
def sub_page1_index():
pass

I have solution for myself how to load blueprints defined in configuration, so then you can have something like CORE_APPS = ('core', 'admin', 'smth') in config and when you construct app you can register those apps (of course those strings in CORE_APPS must be the names of the files you want to import in your python path).
So I'm using function to create app:
app = create_app()
def create_app():
app = Flask(__name__)
# I have class for my configs so configuring from object
app.config.from_object('configsClass')
# does a lot of different stuff but the main thing could help you:
from werkzeug.utils import import_string
for app in app.config['CORE_APPS']
real_app = import_string(app)
app.register_blueprint(real_app)
After that your blueprint should be registered. Of course you can have different format in configs to support custom url prefixes and so on and so on :)
Of course you can also do something like this in your main blueprint, so in the application creation you will need to register that one main blueprint.

set namespace for all db operations

I'm trying to set the namespace for all DB operations for the Google App Engine in python, but i can't get it done.
Currently my code looks something like this:
""" Set Google namespace """
if user:
namespace = thisUser.namespace
namespace_manager.set_namespace(namespace)
""" End Google namespace """
#Then i have all sorts of classes:
class MainPage(BaseHandler):
def get(self):
#code with DB operations like get and put...
class MainPage2(BaseHandler):
def get(self):
#code with DB operations like get and put...
class MainPage3(BaseHandler):
def get(self):
#code with DB operations like get and put...
app = webapp2.WSGIApplication([ ... ], debug=True, config=webapp2_config)
The problem with this is, is that in the classes all DB operations are still done on the default namespace (so as if no namespace is set). Eventhough i set the namespace in the very top of my code.
When i print the variable "namespace", which i also set in the top of the code, then i do get to see the namespace that i wish to use.
But it looks like Google App Engine somewhere resets the namespace to empty before running the code in the classes.
So now i'm wondering if there's a good way to set the namespace once somewhere.
Currently i set it like this in all "def's":
class MainPage(BaseHandler):
def get(self):
namespace_manager.set_namespace(namespace)
#code with DB operations like get and put...
class MainPage(BaseHandler):
def get(self):
namespace_manager.set_namespace(namespace)
#code with DB operations like get and put...
etc...
It's just not a very elegant solution.

You need to write a middleware that will intercept the request and will set the namespace according to your app logic.

A good solution is to add a hook. Something like that should be works.
from google.appengine.api import apiproxy_stub_map
NAMESPACE_NAME = 'noname'
def namespace_call(service, call, request, response):
if hasattr(request, 'set_name_space'):
request.set_name_space(NAMESPACE_NAME)
apiproxy_stub_map.apiproxy.GetPreCallHooks().Append(
'datastore-hooks', namespace_call, 'datastore_v3')
You can add it in your main.py or appengine_config.py. By this way the hook is configured during the loading of the instances and keeps his state.

You can use appconfig.py and define namespace_manager_default_namespace_for_request()
Have a read of https://developers.google.com/appengine/docs/python/multitenancy/multitenancy see the first section of "Setting the Current Namespace"