Maya: Account for no placeholder set.

[tokejepsen]

Changelog Description

When building a template from the current scene with Load template, the below error would occur.

# ==============================
# No object matches name: PLACEHOLDERS_SET
# ==============================
# Traceback (most recent call last):
#   File "C:\Users\tokejepsen\ayon-core\client\ayon_core\pipeline\workfile\workfile_template_builder.py", line 722, in populate_scene_placeholders
#     placeholder_plugin.populate_placeholder(placeholder)
#   File "C:\Users\tokejepsen\ayon-core\client\ayon_core\hosts\maya\api\workfile_template_builder.py", line 246, in populate_placeholder
#     self.populate_load_placeholder(placeholder)
#   File "C:\Users\tokejepsen\ayon-core\client\ayon_core\pipeline\workfile\workfile_template_builder.py", line 1639, in populate_load_placeholder
#     self.post_placeholder_process(placeholder, failed)
#   File "C:\Users\tokejepsen\ayon-core\client\ayon_core\hosts\maya\api\workfile_template_builder.py", line 266, in post_placeholder_process
#     cmds.sets(node, addElement=PLACEHOLDER_SET)
TypeError: No object matches name: PLACEHOLDERS_SET

Testing notes:

1. Open new scene in Maya.
2. Using Loader on a workfile or mayaScene, prepped as a template, using Load as template.

[BigRoy]

Shouldn't the file you're loading/building with contain the placeholder_SET. If not, does that technically mean you're loading a scene that has no placeholders to begin with so there's nothing to build?

I'm not sure why the placeholder set pre-existing originally was a requirement but I wonder if that not being the case would now hide another issue instead?

[LiborBatek]

@BigRoy to me its seems like just one unneccessary limitation was removed...I guess you could use just a template file containing loaded assets not any placeholders at all for example?

[LiborBatek]

LGTM, I dont experience any kind of errors regarding non existent placeholder set.

I guess its good to go...

[BigRoy]

I guess you could use just a template file containing loaded assets not any placeholders at all for example?

Well, that would be odd - no? Since if it has no placeholders, then there's nothing to run in the workfile template system?

[tokejepsen]

Well, that would be odd - no? Since if it has no placeholders, then there's nothing to run in the workfile template system?

I get this when having a blank Maya scene and use the "Load as template" action.

[BigRoy]

I get this when having a blank Maya scene and use the "Load as template" action.

I guess you're building it from a scene that should've contained the placeholder SET to begin with but it didn't?
Again, I technically don't know why the set was required to begin with so I'm not too bother by the change. Just wonder whether there originally was reason for it to be required :D

[BigRoy]

Looks fine to me.

[LiborBatek]

just did one more test with practically empty template file and all good...it behaves predictably and also gives warning msg if no placeholders found

WRN: >>> { <ayon_core.hosts.maya.api.workfile_template_builder.MayaTemplateBuilder object at 0x000001CA288A7160> }: [ No placeholders were found. ] 

[LiborBatek]

I did tested and works ok.