RuntimeError：资产实例未绑定到应用程序，当前上下文中没有应用程序

Question

我正在努力修改cookiecutter Flask应用。我目前正在尝试向页面添加日期选择器。我找到了https://eonasdan.github.io/bootstrap-datetimepicker/。这个cookiecutter使用flask-assets来管理项目资产。

关注https://adambard.com/blog/fresh-flask-setup/我修改了我的assets.py文件：

from flask_assets import Bundle, Environment
import os

css = Bundle(
    "libs/bootstrap/dist/css/spacelab/bootstrap.css",
    "bower_components/eonasdan-bootstrap-datetimepicker/build/css/bootstrap-datetimepicker.css",
    "css/style.css",
    "css/home.css",
    # "css/style.css",
    filters="cssmin",
    output="public/css/common.css"
)

js = Bundle(
    "libs/jQuery/dist/jquery.js",
    "libs/bootstrap/dist/js/bootstrap.js",
    "bower_components/moment/moment.js",
    "bower_components/eonasdan-bootstrap-datetimepicker/build/js/bootstrap-datetimepicker.min.js",
    "js/plugins.js",
    filters='jsmin',
    output="public/js/common.js"
)

# Tell flask-assets where to look for our coffeescript and sass files.
assets = Environment()
assets.load_path = [os.path.join(os.path.dirname(__file__), 'myflaskapp/static/bower_components')]

assets.register("js_all", js)
assets.register("css_all", css)

当我这样做时，我得到：

Traceback (most recent call last):
  File "C:/envs/r2/myproject/manage.py", line 8, in <module>
    from myflaskapp.app import create_app
  File "C:\envs\r2\myproject\myflaskapp\app.py", line 8, in <module>
    from myflaskapp.assets import assets
  File "C:\envs\r2\myproject\myflaskapp\assets.py", line 41, in <module>
    assets.load_path = [os.path.join(os.path.dirname(__file__), 'myflaskapp/static/bower_components')]
  File "C:\envs\virtalenvs\flask_myproject\lib\site-packages\webassets\env.py", line 639, in _set_load_path
    self._storage['load_path'] = load_path
  File "C:\envs\virtalenvs\flask_myproject\lib\site-packages\flask_assets.py", line 104, in __setitem__
    self.env._app.config[self._transform_key(key)] = value
  File "C:\envs\virtalenvs\flask_myproject\lib\site-packages\flask_assets.py", line 292, in _app
    'and no application in current context')
RuntimeError: assets instance not bound to an application, and no application in current context

我做错了什么？

编辑：app.py初始化资产：

from flask import Flask, render_template
from myflaskapp.assets import assets

    :param config_object: The configuration object to use.
    """
    app = Flask(__name__)
    app.config.from_object(config_object)
    register_extensions(app)
    register_blueprints(app)
    register_errorhandlers(app)
    return app

def register_extensions(app):
    assets.init_app(app)

def register_blueprints(app):
    app.register_blueprint(public.blueprint)
    app.register_blueprint(user.blueprint)

Answer 1

正如我在评论中指出的那样，你需要绑定到该对象的Flask应用程序，正如它在回溯中所述：

>>> RuntimeError: assets instance not bound to an application, and no 
    application in current context

这将解决您的问题，无论它是否与您的用例相关......：

def register_extensions(app):
    assets.init_app(app)
    with app.app_context():
         assets.load_path = ['static']

或者您可以重新编写您的创建应用

def create_assets(app):
    assets = Environment(app)
    ....
    assets.load_path ['static']
    return assets

def create_app():
    app = Flask()
    ....
    assets = create_assets(app)
    return app

您的错误的全部原因是您致电load_path。这会尝试在webassets中设置属性，您可以在此处看到：https://github.com/miracle2k/webassets/blob/95dff0ad6dcc25b81790a1585c67f5393e7d32af/src/webassets/env.py#L656

def _set_load_path(self, load_path):
    self._storage['load_path'] = load_path

反过来，这会激活您在flask-asset对象上的_storage属性，从而导致它尝试执行此操作：https://github.com/miracle2k/flask-assets/blob/eb7f1905410828689086b80eb19be9331041ac52/src/flask_assets.py#L102

def __setitem__(self, key, value):
    if not self._set_deprecated(key, value):
        self.env._app.config[self._transform_key(key)] = value

如您所见，它需要访问某个应用，并且当您使用load_path时没有给出它，它会向您抱怨，因为它在Traceback中解释得非常好。我在flask-asset页面上找到了关于此问题的讨论：https://github.com/miracle2k/flask-assets/issues/35

你可以非常正确地认为，当你打电话给init_app()时，一切都应该没问题，但情况并非如此，init_app()并未提及app至{ {1}}：https://github.com/miracle2k/flask-assets/blob/eb7f1905410828689086b80eb19be9331041ac52/src/flask_assets.py#L338

Environment

我根本不使用flask-assets，所以我不太清楚为什么他们没有用def init_app(self, app): app.jinja_env.add_extension('webassets.ext.jinja2.AssetsExtension') app.jinja_env.assets_environment = self 引用app，所以如果其他人知道，那就喊出去了