Nested Blueprints in Flask?

Question

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 s

Answer 1

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.

Answer 2

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.

Answer 3

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
:)