Fix Maya legacy renderlayer being unable to duplicate (it doesn't show up correctly, but it does create a new renderLayer node visible when Show DAG nodes only is disabled)

maya_renderlayer_fix_unable_to_duplicate.py

# Fix Maya bug where you cannot duplicate a renderlayer correctly bug
# This is with Legacy Renderlayers, not Render Setup.
# Bug has been found in both Maya 2018 + 2019

import maya.cmds as mc

# Recreate all renderlayer overrides (.adjustments)
for layer in mc.ls(type="renderLayer"):

    attr = layer + ".adjustments"
    indices = mc.getAttr(attr, multiIndices=True) or []
    
    connections = []
    for index in indices:
        
        # Collect current connection
        index_attr = "{plug}[{index}]".format(plug=attr, index=index)
        src = cmds.listConnections(index_attr + ".plug", 
                                   source=True, 
                                   plugs=True)[0]
        value = cmds.getAttr(index_attr + ".value")
        connections.append((src, value))

        # Remove the entry and break any connections
        mc.removeMultiInstance(index_attr, b=True)
        
    # Recreate the overrides
    for i, (src, value) in enumerate(connections):
        cmds.connectAttr(src, layer + ".adjustments[{0}].plug".format(i))

@RocketeerVFX That's interesting. As if the renderLayerManager.renderLayerId has zero indices, odd.

Anyway, this would work around that particular error:

# Fix maya duplicated renderlayer not showing up in Render Layer editor

from maya import cmds
from maya import mel
import re
import itertools
from collections import defaultdict


def pairwise(iterable):
    """s -> (s0,s1), (s2,s3), (s4, s5), ..."""
    a = iter(iterable)
    return itertools.izip(a, a)


layers = cmds.ls(type="renderLayer")
for layer in layers:
    
    # Check for missing connection for renderLayer.renderInfo.identification
    id_input = cmds.listConnections(layer + ".identification",
                                    source=True,
                                    destination=False) or []
    if not id_input:
        # Connect it to the render layer manager to show up
        # in the render layer editor as that defines "all
        # layers" by those connected to the renderlayer 
        # manager node.
        layer_manager = cmds.ls(type="renderLayerManager")[0]
        connections = cmds.listConnections(layer_manager + ".renderLayerId",
                                           connections=True,
                                           plugs=True) or []
        sources = [src for src, dest in pairwise(connections)]
        indices = []
        for source in sources:
            match = re.match(r".*\[([0-9]+)\]$", source)
            index = int(match.group(1)) + 1
            indices.append(index)
            indices.sort()
        
        next_index = indices[-1] if indices else 0
            
        src = "{0}.renderLayerId[{1}]".format(layer_manager, next_index)
        dest = "{0}.identification".format(layer)
        print("Fixing missing renderLayerId connection for: %s" % layer)
        print("\t{0} -> {1}".format(src, dest))
        cmds.connectAttr(src, dest, force=True)
                                        
    # Check for missing connection to defaultRenderingList
    # (not sure if required)
    outputs = cmds.listConnections(layer + ".message",
                                   source=False,
                                   destination=True)
    outputs = cmds.ls(outputs, type="defaultRenderingList")
    if not outputs:
        src = layer + ".message"
        dest = "defaultRenderingList1.rendering"
        print("Fixing missing connection to defaultRenderingList for: %s" % layer)
        print("\t{0} -> {1}".format(src, dest))
        cmds.connectAttr(src, dest, nextAvailable=True)
        
# Remove all non-connected renderlayer manager entries
layer_manager = cmds.ls(type="renderLayerManager")[0]
id_plug = layer_manager + ".renderLayerId"       

indices = cmds.getAttr(id_plug, multiIndices=True) or []
for index in reversed(indices):
    id_plug_index = "{0}[{1}]".format(id_plug, index)
    if not cmds.listConnections(id_plug_index,
                                destination=True,
                                source=False):
        print("Removing non-connected index %s" % id_plug_index)
        cmds.removeMultiInstance(id_plug_index)
             
# Fix all numberings for renderlayer manager entries
connections = cmds.listConnections(layer_manager + ".renderLayerId",
                                   connections=True,
                                   plugs=True) or []
for src, dest in pairwise(connections):
    index = int(re.match(r".*\[([0-9]+)\]$", src).group(1))
    if cmds.getAttr(src) != index:
        cmds.setAttr(src, index)
        
# Force renderlayer editor refresh
mel.eval('updateEditorRenderLayer "RenderLayerTab"')

But not sure if it would actually end up perofrming what you'd need to fix the scene. You are using legacy renderlayers, right?
Anyway, if you have a simple reproducible scene I'd be happy to investigate and take a look.

Thanks I'll try that :)
Yeah its legacy renderlayers.
I wish I could share it, but its all on pipe with ftrack dependencies. Which is partly what I'm thinking is causing the issues anyways. Some reference or similar.

It ran this time but sadly no joy. :/

Force renderlayer editor refresh

mel.eval('updateEditorRenderLayer "RenderLayerTab"')
Fixing missing renderLayerId connection for: BTY_ASIA1
prop_bridge:renderLayerManager.renderLayerId[2] -> BTY_ASIA1.identification
Fixing missing connection to defaultRenderingList for: BTY_ASIA1
BTY_ASIA1.message -> defaultRenderingList1.rendering