Maya discovery of the day

if you’re looking for all objects with a specific attribute, it is nice to know that ls and it’s wildcards also work on attributes! It even does not care whether you supply the long or the short name. To get all objects with a translateX attribute you can simply use:

cmds.ls('*.tx')

Wildcards do not work with some other modifiers however, so you can not do this:

cmds.ls('*.myMetaData', l=True, type='mesh', sl=True)

because the returned type is not a mesh, but an attribute; but you can of course do this (notice the o=True to return object names not attributes):

cmds.ls(cmds.ls('*.myMetaData', o=True), l=True, type='mesh', sl=True)

Just wanted to share that bit of information! And while we’re at it, python supports ‘or’ in arbitrary expressions, so if you wish to find all transforms that contain a mesh (or get the transforms of selected meshes at the same time), you’ll often find yourself doing this:

selected_transforms = cmds.ls(type='transform', sl=True, l=True)
selected_meshes = cmds.ls(type='mesh', sl=True, l=True)
if selected_transforms is not None:
    meshes = cmds.listRelatives(selected_transforms, c=True, type='mesh', f=True)
    if meshes is not None:
        if selected_meshes is not None:
            selected_meshes += meshes
        else:
            selected_meshes = meshes
selected_mesh_transforms = []
if selected_meshes is not None:
    selected_mesh_transforms = cmds.listRelatives(selected_meshes, p=True)

just because ls and listRelatives return None instead of an empty list this code is super complicated. With ‘or’ we can simply do this:

meshes = (cmds.ls(type='mesh', sl=True, l=True) or []) + (cmds.listRelatives(cmds.ls(type='transform', sl=True, l=True), c=True, type='mesh', f=True) or [])
selected_mesh_transforms = cmds.listRelatives(meshes, p=True, f=True) or []

Admittedly a bit less readable, but make a utility function or name variables appropriately is my advice!

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