How can I set the color/material of an object added/appended from another file?

Question

It is not possible to set the color of the object added from the file. What am I doing wrong?

import bpy
import os
from pathlib import Path


file_path = 'd:/BlendetSkin002/280154.blend'      
inner_path = 'Object'           
object_name = 'scirt01'         


def append_scirt( path: Path):
    bpy.ops.wm.append(
            filepath=os.path.join(file_path, inner_path, object_name),
            directory=os.path.join(file_path, inner_path),
            filename=object_name,
            active_collection = True
            )
    rgba_color = (220, 0, 220, 0.99)
    material = bpy.data.materials.new(f"scirt01")
    material.diffuse_color = rgba_color
    bpy.context.active_object.data.materials.append(material)
    bpy.context.object.active_material.diffuse_color = rgba_color


append_scirt( Path(f'd:/BlendetSkin002/280154.blend'))

Answer 1

When you append an object from another file it is not fully selected, as seen in the orange outline. It has to have yellow outline to be active. That's why bpy.context.object and bpy.context.active_object return nothing. After appending just add the line bpy.context.view_layer.objects.active = bpy.context.scene.objects.get(object_name) to make it the active object.

import bpy
import os
from pathlib import Path

file_path = 'd:/BlendetSkin002/280154.blend'      
inner_path = 'Object'           
object_name = 'scirt01'         

def append_scirt( path: Path):
    bpy.ops.wm.append(
            filepath=os.path.join(file_path, inner_path, object_name),
            directory=os.path.join(file_path, inner_path),
            filename=object_name,
            active_collection = True
            )
    bpy.context.view_layer.objects.active = bpy.context.scene.objects.get(object_name)
    rgba_color = (220, 0, 220, 0.99)
    material = bpy.data.materials.new(f"scirt01")
    material.diffuse_color = rgba_color
    bpy.context.active_object.data.materials.append(material)
    bpy.context.object.active_material.diffuse_color = rgba_color

append_scirt(Path(file_path))