Project injection in Dash callbacks

This section covers common issues encountered when the solution project instance is not injected as expected into a Dash callback. See Project injection in callbacks for a description of the injection mechanism.

When encountering issues with project injection, follow these debugging steps:

1. Verify type hints: Ensure all callback arguments have proper type annotations.

2. Check Dash version: Confirm you’re using Dash 3.0.0 or higher:

   import dash
   
   print(dash.__version__)
   

3. Validate project type: Make sure your project type annotation matches your solution class:

   from ansys.solutions.your_solution.definition import YourSolution
   
   
   @callback(State("url", "pathname"))
   def my_callback(project: YourSolution):  # Use your actual solution class
       pass
   

4. Check import statements: Ensure you’re importing the callback decorator from the correct module:

   from ansys.saf.glow.client import callback  # Correct import
   

5. Enable debug logging: Add logging to help diagnose issues:

   import logging
   
   logging.basicConfig(level=logging.DEBUG)
   
   
   @callback(State("url", "pathname"))
   def my_callback(project: YourSolution):
       logging.debug(f"Project injected: {type(project)}")
       # Your callback logic
       pass