flask_asset seems to not find sass file but directory is ok

Question

I m trying for the first time to use flask_asset. this is my init.py code:

from application import assets
    def create_app(config_name):
        app = Flask(__name__, instance_relative_config=True)
        # security
        app.config['SECRET_KEY'] = SECRET_KEY
        # trace db modifications
        app.config['SQLALCHEMY_TRACK_MODIFICATIONS'] = False
    
    
        # Ensure responses aren't cached
        @app.after_request
        def after_request(response):
            response.headers["Cache-Control"] = "no-cache, no-store, must-revalidate"
            response.headers["Expires"] = 0
            response.headers["Pragma"] = "no-cache"
            return response
    
        # Ensure templates are auto-reloaded
        app.config["TEMPLATES_AUTO_RELOAD"] = True
    
    
        # define where is database
        app.config['SQLALCHEMY_DATABASE_URI'] = SQLALCHEMY_DATABASE_URI
    
        db.init_app(app)
    
        Bootstrap(app)
    
        # Assets for CSS and JS
        assets_env = Environment(app)
        assets_loader = PythonAssetsLoader(assets)
        for name, bundle in assets_loader.load_bundles().items():
            assets_env.register(name, bundle)

I create an assets.py file:

from flask_assets import Bundle
public_layout_css = Bundle(
    'sass/milligram/milligram.sass',
    'sass/utils.sass',
    'sass/public.sass',
    filters=['sass', 'cssmin'],
    output='public/public.min.css'
)

And in my html file :

{% block css %}
  {% assets "public_layout_css" %}
      <link rel="stylesheet" href="{{ ASSET_URL }}" />
  {% endassets %}
{% endblock %}

When I try to run html page this is the error:

raise child_exception_type(errno_num, err_msg, err_filename)

FileNotFoundError: [Errno 2] No such file or directory: 'sass': 'sass'

But in my static directory I have sass folder with these files in:

sass/milligram/milligram.sass
sass/utils.sass
sass/public.sass

Where is my mistake ? Thanks

Answer 1

this was due to sass library not properly installed. Pycharm seems having issue to add this library directly...