Export and Import Display Layers in Maya Python

import os
import json
import maya.cmds as cmds

def export_display_layers_to_json(output_path=r"D:\maya_display_layers.json"):
    """
    Exports all custom display layers and their members to a JSON file,
    excluding the default layer.
    """
    layers = cmds.ls(type="displayLayer")
    layer_data = {}
    
    for layer in layers:
        # Skip the default layer
        if layer == "defaultLayer":
            continue
            
        # Get members of the layer. Returns None if empty.
        members = cmds.editDisplayLayerMembers(layer, query=True)
        layer_data[layer] = members if members else []
        
    # Ensure the directory exists
    dir_name = os.path.dirname(output_path)
    if not os.path.exists(dir_name):
        try:
            os.makedirs(dir_name)
        except Exception as e:
            cmds.error(f"Could not create directory {dir_name}: {e}")
            return

    # Write the dictionary to a JSON file
    try:
        with open(output_path, 'w', encoding='utf-8') as json_file:
            json.dump(layer_data, json_file, indent=4, sort_keys=True)
            
        cmds.confirmDialog(
            title="Export Successful", 
            message=f"Display layers exported to:\n{output_path}", 
            button=["OK"]
        )
        print(f"// Success: Display layers exported to {output_path} //")
        
    except Exception as e:
        cmds.error(f"Failed to write JSON file: {e}")

# Run the script
export_display_layers_to_json()

import maya.cmds as cmds 
import os
import json 

def add_display_layers(input_path=r"D:\maya_display_layers.json"):
    """
    Imports display layers and their members from a JSON file.
    Recreates layers if they don't exist and reassigns objects,
    overriding any existing layer assignments.
    """
    # 1. Check if the file exists
    if not os.path.exists(input_path):
        cmds.error(f"JSON file not found at: {input_path}")
        return

    # 2. Read the JSON data
    try:
        with open(input_path, 'r', encoding='utf-8') as json_file:
            layer_data = json.load(json_file)
    except Exception as e:
        cmds.error(f"Failed to read JSON file: {e}")
        return

    # 3. Process each layer and its members
    for layer_name, members in layer_data.items():
        # Skip default layer just in case it sneaked into the JSON
        if layer_name == "defaultLayer":
            continue

        # Create the display layer if it doesn't exist
        if not cmds.objExists(layer_name):
            layer_name = cmds.createDisplayLayer(empty=True, name=layer_name)
            print(f"// Created display layer: {layer_name} //")

        if not members:
            continue

        # Filter members to only include objects that actually exist in the current scene
        valid_members = [obj for obj in members if cmds.objExists(obj)]
        missing_members = [obj for obj in members if not cmds.objExists(obj)]

        if missing_members:
            print(f"// Warning: Missing scene objects skipped for layer '{layer_name}': {missing_members} //")

        # Assign valid objects to the layer
        for obj in valid_members:
            # Force assignment: editDisplayLayerMembers overrides existing layers automatically,
            # but explicitly doing it ensures the JSON mapping strictly prevails.
            try:
                cmds.editDisplayLayerMembers(layer_name, obj, noRecurse=True)
            except Exception as e:
                print(f"// Warning: Could not assign '{obj}' to '{layer_name}': {e} //")

    print(f"// Success: Display layers setup complete from {input_path} //")

add_display_layers()