Fix for #135 bpy.context.[active_]object set to None after adding primitive when run from VS Code Extension

[CGArtPython]

Summary of issue

Calling a script via operator results in an empty context.

Related devtalk.blender

from @JacquesLucke
https://devtalk.blender.org/t/how-to-run-a-script-from-outside-blender-script-live-link-addon/9792/3?u=jacqueslucke

Solution

Use bpy.app.timers to register a function to run the target script.

Changes

pythonFiles\include\blender_vscode\operators\script_runner.py

• remove the RunScriptOperator and move the contents of the execute method into a the run_script() function
• register a timer callback to the run_script() function that will execute the target script

Potentially related issues

• When adding objects to collections the objects only show after the script ends. When adding objects to collections the objects only show after the script ends. #101
• accessing bpy.context.object crashes Blender accessing bpy.context.object crashes Blender #86
• Crash when adding mesh Crash when adding mesh #63
• Delete is skipped Delete is skipped #68

Testing

• execute a simple script that uses bpy.context.active_object
• set the #context.area: SEQUENCE_EDITOR and run this script https://github.com/CGArtPython/blender_plus_python/blob/main/sequence_editor_frame_import/sequence_editor_frame_import_done.py
• execute the script from issue When adding objects to collections the objects only show after the script ends. #101 When adding objects to collections the objects only show after the script ends. #101
• execute the script from issue accessing bpy.context.object crashes Blender #86 accessing bpy.context.object crashes Blender #86
• execute the script from issue Crash when adding mesh #63 Crash when adding mesh #63
• execute the script from issue Delete is skipped #68 Delete is skipped #68
• execute the script from issue Problems with context #41 Problems with context #41

[CGArtPython]

Ready to make any changes based on the code review.

I can also move this code out of the operator's folder since it no longer contains the operator.

[JacquesLucke]

I was just looking into the issue and it seems like the proposed fix does not work generally. It essentially removes the context-overrides created by prepare_script_context. This happens to fix your script but can break other code. For example, see what happens when you print bpy.context.space_data in the script: In master this prints the 3d view space, but with this patch the result is None.

I think the core issue for what causes the issue in #135 is that the context changes while the script is executed and the context-override is not valid anymore. The diff below also seems to fix the bug for me, maybe you can try that as well. The idea is that we only override the "important" part of the context, and leave the rest for Blender to figure out when actually accessing e.g bpy.context.active_object.

diff --git a/pythonFiles/include/blender_vscode/operators/script_runner.py b/pythonFiles/include/blender_vscode/operators/script_runner.py
index 9159b90..a1d022d 100644
--- a/pythonFiles/include/blender_vscode/operators/script_runner.py
+++ b/pythonFiles/include/blender_vscode/operators/script_runner.py
@@ -42,16 +42,8 @@ def prepare_script_context(filepath):
     context["view_layer"] = context["window"].view_layer
     context["screen"] = context["window"].screen
     context["workspace"] = context["window"].workspace
-    context["active_object"] = context["view_layer"].objects.active
-    context["object"] = context["active_object"]
-    context["collection"] = context["view_layer"].active_layer_collection.collection
     context["area"] = get_area_by_type(area_type)
-    context["space_data"] = context["area"].spaces.active
-    context["selected_objects"] = [obj for obj in context["view_layer"].objects if obj.select_get(view_layer=context["view_layer"])]
-    context["selected_editable_objects"] = context["selected_objects"]
     context["region"] = get_region_in_area(context["area"], region_type) if context["area"] else None
-    if context["space_data"].type == "VIEW_3D":
-        context["region_data"] = context["space_data"].region_3d
     return context
 
 def get_area_by_type(area_type):

[CGArtPython]

I was just looking into the issue and it seems like the proposed fix does not work generally. It essentially removes the context-overrides created by prepare_script_context. This happens to fix your script but can break other code. For example, see what happens when you print bpy.context.space_data in the script: In master this prints the 3d view space, but with this patch the result is None.

I think the core issue for what causes the issue in #135 is that the context changes while the script is executed and the context-override is not valid anymore. The diff below also seems to fix the bug for me, maybe you can try that as well. The idea is that we only override the "important" part of the context, and leave the rest for Blender to figure out when actually accessing e.g bpy.context.active_object.

diff --git a/pythonFiles/include/blender_vscode/operators/script_runner.py b/pythonFiles/include/blender_vscode/operators/script_runner.py
index 9159b90..a1d022d 100644
--- a/pythonFiles/include/blender_vscode/operators/script_runner.py
+++ b/pythonFiles/include/blender_vscode/operators/script_runner.py
@@ -42,16 +42,8 @@ def prepare_script_context(filepath):
     context["view_layer"] = context["window"].view_layer
     context["screen"] = context["window"].screen
     context["workspace"] = context["window"].workspace
-    context["active_object"] = context["view_layer"].objects.active
-    context["object"] = context["active_object"]
-    context["collection"] = context["view_layer"].active_layer_collection.collection
     context["area"] = get_area_by_type(area_type)
-    context["space_data"] = context["area"].spaces.active
-    context["selected_objects"] = [obj for obj in context["view_layer"].objects if obj.select_get(view_layer=context["view_layer"])]
-    context["selected_editable_objects"] = context["selected_objects"]
     context["region"] = get_region_in_area(context["area"], region_type) if context["area"] else None
-    if context["space_data"].type == "VIEW_3D":
-        context["region_data"] = context["space_data"].region_3d
     return context
 
 def get_area_by_type(area_type):

You are right!
Just tested one of my scripts that use context.space_data, and that script failed with my change.

I tested it with my scripts, and it looks like everything is working!

I can close this PR.
Would you be able to submit your fix?

[JacquesLucke]

I committed the alternative fix in 621e275.