Hi,

Please refer to the code:

# Suppose you already have:

# product_template_id -> ID of product.template

# attribute_id -> ID of 'Size' attribute

# product_attribute_value_ids -> list of value IDs for sizes [id_7, id_8, id_9]

# 1. Check if the attribute line already exists for this template

existing_lines = lnk_dbcom.execute(

    'product.template.attribute.line', 'search',

    [[

        ('product_tmpl_id', '=', product_template_id),

        ('attribute_id', '=', attribute_id),

    ]]

)

if existing_lines:

    # 2. Update the existing line with all size value_ids

    lnk_dbcom.execute(

        'product.template.attribute.line', 'write',

        existing_lines,

        {'value_ids': [(6, 0, product_attribute_value_ids)]}

    )

else:

    # 3. Create a new attribute line with all size values

    lnk_dbcom.execute(

        'product.template.attribute.line', 'create',

        [{

            'product_tmpl_id': product_template_id,

            'attribute_id': attribute_id,

            'value_ids': [(6, 0, product_attribute_value_ids)]

        }]

    )

Hope it helps.

Final working code: (thx)

def  get_attribute_line_id (product_template_id, attribute_id, value_ids, create= True ):
     # Search for existing attribute line on the product
    existing_line_ids = lnk_dbcom.execute(
        'product.template.attribute.line' , 'search' ,
        [[
            [ 'product_tmpl_id' , '=' , product_template_id],
            [ 'attribute_id' , '=' , attribute_id]
        ]]
    )

    # If it doesn't exist and creation is allowed, create it
    if not existing_line_ids and create:
        print('create: ', product_template_id, attribute_id, value_ids)
        line_id = lnk_dbcom.execute(
            'product.template.attribute.line', 'create',
            [{
                'product_tmpl_id' : product_template_id,
                'attribute_id' : attribute_id,
                'value_ids' : [( 6 , 0 , value_ids)]
            }]
        )
        existing_line_ids = [line_id]

    return existing_line_ids