Why does "nw_add_textures_for_principled" work w/ Existing Material but not w/ dynamically created ones?

Question

I have a default cube ‘Cube’ which has 1 default material (active_material_index = 0). I’m adding another material dynamically via script that adds a Principled BSDF texture setup (CTRL+SHIFT+T) for this second material at active_material_index = 1 using bpy.ops.node.nw_add_textures_for_principled() as in the code below. The weird thing is that if i use active_material_index = 0 or any index for a material that already exists and have its Principled BSDF node already selected, the script actually works and properly adds the texture setup. But it doesn't work if you dynamically create the material and dynamically select the Principled BSDF node (white outline). It looks like something asynchronous is happening where the creation of the material is not ready yet when nw_add_textures_for_principled executes. Any idea? If the problem was the context, then how was it possible to work for the existing material?

import bpy

mat = bpy.data.materials.new(name='dynamically_created')
mat.use_nodes = True

bpy.data.objects['Cube'].data.materials.append(mat)
bpy.context.object.active_material_index = 1

bpy.context.area.ui_type = 'ShaderNodeTree'
bpy.context.area.type = 'NODE_EDITOR'

m = bpy.context.object.active_material
m.node_tree.nodes['Material Output'].select = False
m.node_tree.nodes['Principled BSDF'].select = True
m.node_tree.nodes.active = m.node_tree.nodes.get("Principled BSDF")

r = bpy.ops.node.nw_add_textures_for_principled(filepath="E:\\ZZZZ\\Projects\\blender\\textures\\metal\\Metal021_1K-JPG\\", directory="E:\\ZZZZ\\Projects\\blender\\textures\\metal\\Metal021_1K-JPG\\", files=[ {"name":"Metal021_1K_Color.jpg", "name":"Metal021_1K_Color.jpg"}, {"name":"Metal021_1K_Displacement.jpg", "name":"Metal021_1K_Displacement.jpg"}, {"name":"Metal021_1K_Metalness.jpg", "name":"Metal021_1K_Metalness.jpg"}, {"name":"Metal021_1K_NormalDX.jpg", "name":"Metal021_1K_NormalDX.jpg"}, {"name":"Metal021_1K_NormalGL.jpg", "name":"Metal021_1K_NormalGL.jpg"}, {"name":"Metal021_1K_Roughness.jpg", "name":"Metal021_1K_Roughness.jpg"}, {"name":"Metal021_PREVIEW.jpg", "name":"Metal021_PREVIEW.jpg"}], relative_path=True)
print("result ==== ", r) #{'CANCELLED'}

UPDATE w/ Marty Fouts' Answer:

Thanks to Marty Fouts the context usage is properly implemented now but:

When I manually select the Principled BSDF node of material at index 0 (aka the already-existing material), the script does add the texture node setup but to material of index 0:

When NO Principled BSDF shader node is selected and i want the script to select this node from material index 1 (aka the dynamically generated material) it selects the node but unfortunately does NOT add the texture setup as I would have expected. The result is:

Hence the issue as described in the question title of this thread still persists

Here's the new complete script (make sure to use the default cube that already has 1 material on slot index 0):

import bpy

object = bpy.context.active_object
material = bpy.data.materials.new(name='dynamically_created')

object.data.materials.append(material)
object.active_material_index = len(object.material_slots) - 1

material.use_nodes = True
tree = material.node_tree
nodes = tree.nodes

material.node_tree.nodes['Material Output'].select = False
material.node_tree.nodes['Principled BSDF'].select = True

material.node_tree.nodes.active = material.node_tree.nodes.get("Principled BSDF")

filepath="E:\\ZZZZ\\Projects\\blender\\textures\\metal\\Metal021_1K-JPG\\"
directory="E:\\ZZZZ\\Projects\\blender\\textures\\metal\\Metal021_1K-JPG\\"
files=[
    {"name":"Metal021_1K-JPG.usda", "name":"Metal021_1K-JPG.usda"},
    {"name":"Metal021_1K-JPG.usdc", "name":"Metal021_1K-JPG.usdc"},
    {"name":"Metal021_1K_Color.jpg", "name":"Metal021_1K_Color.jpg"},
    {"name":"Metal021_1K_Displacement.jpg", "name":"Metal021_1K_Displacement.jpg"},
    {"name":"Metal021_1K_Metalness.jpg", "name":"Metal021_1K_Metalness.jpg"},
    {"name":"Metal021_1K_NormalDX.jpg", "name":"Metal021_1K_NormalDX.jpg"},
    {"name":"Metal021_1K_NormalGL.jpg", "name":"Metal021_1K_NormalGL.jpg"},
    {"name":"Metal021_1K_Roughness.jpg", "name":"Metal021_1K_Roughness.jpg"},
    {"name":"Metal021_PREVIEW.jpg", "name":"Metal021_PREVIEW.jpg"},
]
relative_path=True


#-----------------------------------------------------------------------------
#
# Starting in 3.2 context overrides are deprecated in favor of temp_override
# https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override
#
# They are scheduled to be removed in 3.3
#
def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
        
win = bpy.context.window
scr = win.screen
areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
regions = [region for region in areas[0].regions if region.type == 'WINDOW']

if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas[0], region=regions[0],
        screen=scr):
            bpy.ops.node.nw_add_textures_for_principled(
                filepath=filepath,
                directory=directory,
                files=files,
                relative_path=relative_path
            )
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas[0],
        'region': regions[0],
    }
    bpy.ops.node.nw_add_textures_for_principled(
        override,
        filepath=filepath,
        directory=directory,
        files=files,
        relative_path=relative_path
    )

Answer 1

Your problem starts with the fact that bpy.context.area is meant to be read-only. The randomness of behavior stems from that.

You need to establish a context override to use the node wrangler function. But that means you need to deal with context override dictionaries being deprecated in 3.2 and scheduled to be removed in 3.3. Here's a way to deal with that:

#-----------------------------------------------------------------------------
#
# Starting in 3.2 context overrides are deprecated in favor of temp_override
# https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override
#
# They are scheduled to be removed in 3.3
#
def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
        
win = bpy.context.window
scr = win.screen
areas3d = [area for area in scr.areas if area.type == 'VIEW_3D']
regions = [region for region in areas3d[0].regions if region.type == 'WINDOW']


if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas3d[0], region=regions[0],
        screen=scr):
        print("place your bpy.ops call here, IE bpy.ops.view3d.camera_to_view()")
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas3d[0],
        'region': regions[0],
    }
    print("use an override here, IE bpy.ops.view3d.camera_to_view(override)")

but you're not overriding a 3d view, but rather the shader editor, so you'll need to adjust area and region.

EDIT: Your second problem is that you have to set the object's active_material_index to the index of the newly added material. the Node Wrangler ops operate on the active material. After you've appended the new material you need to add

object.active_material_index = len(object.material_slots) - 1

after

object.data.materials.append(material)

This works because the new material is appended into the last material slot.

Second Edit: As per an exchange described in a comment in the answer, you also need to set the space.active.node_tree for the appropriate Node Editor.

Also, there is a typo in the if statement in the latest version of your script in your question. in the with statement region[0] should be regions[0]. I think that came from my original answer. I've fixed all the spellings in the answer.

Putting it all together, tested with an example from my own collection of textures, but with the names changed:

import bpy

object = bpy.context.active_object
material = bpy.data.materials.new(name='dynamically_created')

object.data.materials.append(material)
object.active_material_index = len(object.material_slots) - 1

material.use_nodes = True
tree = material.node_tree
nodes = tree.nodes

material.node_tree.nodes['Material Output'].select = False
material.node_tree.nodes['Principled BSDF'].select = True

material.node_tree.nodes.active = material.node_tree.nodes.get("Principled BSDF")

filepath= "CHANGE ME"
directory="CHANGE ME"
files=[
    {"name":"CHANGE ME", "name":"CHANGE ME"},
] 
relative_path=True


#-----------------------------------------------------------------------------
#
# Starting in 3.2 context overrides are deprecated in favor of temp_override
# https://docs.blender.org/api/3.2/bpy.types.Context.html#bpy.types.Context.temp_override
#
# They are scheduled to be removed in 3.3
#
def use_temp_override():
    ''' Determine whether Blender is 3.2 or newer and requires
        the temp_override function, or is older and requires
        the context override dictionary
    '''
    version = bpy.app.version
    major = version[0]
    minor = version[1]
    if major < 3 or (major == 3 and minor < 2):
        return False
    else:
        return True
        
win = bpy.context.window
scr = win.screen
areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
regions = [region for region in areas[0].regions if region.type == 'WINDOW']

# Omar Emara informed Harry McKenzie that in order to solve the problem of this script
# working when pasted into the console but not working when run
# "You just need to assign the node tree to the node tree space type because the
# operator uses that."  Harry McKenize posted an answer showing the exact
# method.  I've adapted it to this code's flow.

areas[0].spaces.active.node_tree = material.node_tree

if use_temp_override():
    with bpy.context.temp_override(window=win, area=areas[0], region=regions[0],
        screen=scr):
            bpy.ops.node.nw_add_textures_for_principled(
                filepath=filepath,
                directory=directory,
                files=files,
                relative_path=relative_path
            )
else:
    override = {
        'window': win,
        'screen': scr,
        'area': areas[0],
        'region': regions[0],
    }
    bpy.ops.node.nw_add_textures_for_principled(
        override,
        filepath=filepath,
        directory=directory,
        files=files,
        relative_path=relative_path
    )

You would, of course, have to change the "CHANGE ME" strings and have at least one entry per texture from the directory.

Answer 2

I have finally gotten the last piece of the puzzle thanks to Omar Emara

You just need to assign the node tree to the node tree space type because the operator uses that.

areas  = [area for area in scr.areas if area.type == 'NODE_EDITOR']
areas[0].spaces.active.node_tree = material.node_tree