RuntimeError：资产实例未绑定到应用程序，在当前上下文中没有应用程序 [英] RuntimeError: assets instance not bound to an application, and no application in current context

问题描述

我正在修改 cookiecutter Flask app。我目前正在尝试添加一个日期选择器到一个页面。我找到 https://eonasdan.github.io/bootstrap-datetimepicker/ 。这个cookiecutter使用flask-assets来管理项目资产。

遵循 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 / / bss / 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
）
 
＃电话l flask-assets在哪里查找我们的coffeescript和sass文件。 
 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：
$ b $ pre $ code Traceback最近一次调用最后一个
文件C： /envs/r2/myproject/manage.py，第8行，在< module>
from myflaskapp.app import create_app
在< module>文件中的第8行C：\\\\\\\\\\\\\'
from myflaskapp.assets import assets
在< module>文件中，第41行的文件是C：\\\\\\\\\\\\\\\\\\\\\
assets.load_path = [os.path.join（os.path.dirname（__ FILE__）， 'myflaskapp /静态/ bower_components'）]
档C：\envs\virtalenvs\flask_myproject \lib\site-packages\webassets\env.py，第639行，在_set_load_path
self._storage ['load_path'] = load_path
文件C：\\\\\\\\ virtalenvs\flask_myproject\lib\site-packages\flask_assets.py，第104行，在__setitem__
self.env._app.config [self._transform_key（key）] = value
File C：\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\\ ：资产实例不绑定到应用程序，并且在当前上下文中没有应用程序

我在做什么错误？

编辑：app.py初始化资源：

 从myflask导入Flask，render_template 
 app.assets导入资产
 
：param config_object：要使用的配置对象。 

 app = Flask（__ name__）
 app.config.from_object（config_object）
 register_extensions（app）
 register_blueprints（app）
 register_errorhandlers （app）
返回应用程序
 
 def register_extensions（app）：
 assets.init_app（app）
 $ b $ def register_blueprints（app）：
 app.register_blueprint（public.blueprint）
 app.register_blueprint（user.blueprint）
  

解决方案

正如我在我的评论中指出的那样，你必须将一个Flask应用绑定到该对象上，正如它在traceback中注释的那样：

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

这将解决您的问题，无论是否与您的使用情况相关...：

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

或者你可以重新编写你的创建应用程序来

  def create_assets（app）：
 assets = Environment（app）
 ... 
 assets .load_path ['static'] 
返回资产
 $ b $ def create_app（）：
 app = Flask（）
 .... 
 assets = create_assets （app）
返回应用程序
  

错误的全部原因是您调用 LOAD_PATH 。这将尝试设置webassets属性，你可以在这里看到：的 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，现在激活你的flask-asset对象上的_storage的属性，这导致它试图做到这一点： https://github.com/miracle2k/flask-assets/blob/eb7f1905410828689086b80eb19be9331041ac52/src/flask_assets.py#L102 < （key，value）：

  def __setitem __（self，key，value）：
如果不是self._set_deprecated b self.env._app.config [self._t ransform_key（key）] = value 
  

正如你所见，它需要访问一个应用程序，当你使用 load_path 的时候没有给出它，它会向你抱怨，因为它在Traceback中非常好的解释。我在flask-asset页面上找到了关于这个问题的讨论： https://github.com/你可能很正确地认为，当你调用 init_app（）时， code>一切都应该没问题，但事实并非如此， init_app（）不会引用应用程序的任何引用来环境： https://github.com/miracle2k/flask-assets/blob/eb7f1905410828689086b80eb19be9331041ac52/src/flask_assets.py#L338

  def init_app（self，app）：
 app.jinja_env.add_extension（'webassets.ext.jinja2.AssetsExtension'）
 app.jinja_env.assets_environment = self 
  

我根本不使用烧瓶资产，所以我不确定他们为什么避难用 Environment（）。init_app 引用 app ，所以如果别人知道的话，大喊一声。 p>


I'm working to modify a cookiecutter Flask app. I'm currently trying to add a datepicker to a page. I've found https://eonasdan.github.io/bootstrap-datetimepicker/. This cookiecutter uses flask-assets to manage the project assets.

Following https://adambard.com/blog/fresh-flask-setup/ I've modified my assets.py file :

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)

When I do this I get:

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

What am I doing wrong?

edit: app.py initializes the assets:

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)

解决方案

As I noted in my comment, you have to a Flask app bound to the object, as it notes in the traceback:

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

This will fix your problem, whether or not it's relevant for you use case...:

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

or you could re-write your create app to have

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

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

The whole reason for your errors is your call to load_path. This tries to set the attribute in webassets, which you can see here: 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

In turn, this now activates the attribute of _storage on your flask-asset object, which results in it trying to do this: 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

As you see, it needs access to an app, and as you haven't given one when you used load_path it will complain to you, as it explains so nicely in the Traceback. I found a discussion about this on the flask-asset page: https://github.com/miracle2k/flask-assets/issues/35

You may, quite rightly, think that as you called init_app() that everything should be fine, but that's not the case, init_app() does not give any reference of the app to Environment: https://github.com/miracle2k/flask-assets/blob/eb7f1905410828689086b80eb19be9331041ac52/src/flask_assets.py#L338

def init_app(self, app):
    app.jinja_env.add_extension('webassets.ext.jinja2.AssetsExtension')
    app.jinja_env.assets_environment = self

I don't use flask-assets at all, and so I'm not particularly sure why they haven't referenced the app with the Environment().init_app, so if someone else knows, shout out.

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