Drupal 8 - migrate image field from CSV with multiple values

Question

I'm trying to populate a new Drupal 8 (8.3.2) site with content from a CSV file, using core's Migrate module, Migrate Source CSV, Migrate Tools and Migrate Plus. I'm able to import each node successfully with a single image, but I'm unsure of how to migrate multiple images into the node's multi-value image field.

My module currently looks like this:

id: product_data
label: Products
migration_group: product_migration
migration_tags:
  - node
  - product
source:
  plugin: csv
  path: 'public://import/products/products.full.csv'
  header_row_count: 1
  keys:
    - product_sku
  constants:
    bool_0: 0
    bool_1: 1
    uid_root: 1
    restricted_html: restricted_html
destination:
  plugin: 'entity:node'
  default_bundle: product
process:
  title: product_name
  field_sku: product_sku
  sticky: constants/bool_0
  promote: constants/bool_1
  uid: constants/uid_root
  'field_image/target_id':
      plugin: migration
      migration: product_image
      source: product_full_image
migration_dependencies:
  optional:
    - product_image
dependencies:
  enforced:
    module:
      - custom_migration

And to create the image entities:

id: product_image
label: Images associated with a product.
migration_group: product_migration
migration_tags:
  - product
  - file
  - image
source:
  plugin: csv
  path: 'public://import/products/products.full.csv'
  header_row_count: 1
  keys:
    - product_full_image
  fields:
    product_full_image: Name of the image file associated with the program.
  constants:
    file_source_uri: public://import/products/old-images
    file_dest_uri: 'public://program/image'
destination:
  plugin: 'entity:file'
process:
  file_source:
    -
      plugin: concat
      delimiter: /
      source:
        - constants/file_source_uri
        - product_full_image
    -
      plugin: urlencode
  file_dest:
    -
      plugin: concat
      delimiter: /
      source:
        - constants/file_dest_uri
        - product_full_image
    -
      plugin: urlencode
  filename: product_full_image
  uri:
    plugin: file_copy
    source:
      - '@file_source'
      - '@file_dest'
dependencies:
  enforced:
    module:
      - custom_migration

And the csv file is formatted like this:

product_sku,product_name,product_full_image
C242,couch,Blue Couch,"image1.jpg,image2.jpg"
C243,chair,Red Chair,image3.jpg

I've tried to work with the expload and iterator plugins, but honestly I'm totally lost here. Any ideas would be greatly appreciated.

Answer 1

I was able to figure this out -- hopefully this can help others in the same boat. My final migration looked like this:

Main module:

id: product_data
label: Products
migration_group: product_migration
migration_tags:
  - node
  - product
source:
  plugin: csv
  path: 'public://import/products/products.full.csv'
  header_row_count: 1
  keys:
    - product_sku
  constants:
    bool_0: 0
    bool_1: 1
    uid_root: 1
    restricted_html: restricted_html
destination:
  plugin: 'entity:node'
  overwrite_properties:
    - field_image
  default_bundle: product
process:
  field_image:
    -
      plugin: explode
      delimiter: ;
      source: image
    -
      plugin: migration
      migration: product_image
      no_stub: true
migration_dependencies:
  optional:
    - product_image
dependencies:
  enforced:
    module:
      - custom_migration

The 'products.full.csv' file referenced above lookes like this:

product_sku,product_name,image
C242,Blue Couch,image1.jpg;image2.jpg;image3.jpg
C243,Red Chair,image4.jpg

To import and create entities for all of the images:

id: product_image
label: Import all product images.
migration_group: product_migration
migration_tags:
  - product
  - file
  - image
source:
  plugin: csv
  path: 'public://import/products/images.csv'
  header_row_count: 1
  keys:
    - image
  fields:
    new_image: Name of the image file associated with the program.
  constants:
    file_source_uri: public://import/products/images
    file_dest_uri: 'public://program/image'
destination:
  plugin: 'entity:file'
process:
  file_source:
    -
      plugin: concat
      delimiter: /
      source:
        - constants/file_source_uri
        - new_image
    -
      plugin: urlencode
  file_dest:
    -
      plugin: concat
      delimiter: /
      source:
        - constants/file_dest_uri
        - new_image
    -
      plugin: urlencode
  filename: new_image
  uri:
    plugin: file_copy
    source:
      - '@file_source'
      - '@file_dest'
dependencies:
  enforced:
    module:
      - custom_migration

The 'images.csv' file referenced above only has one column and is just a straight list of all images to create entities for, one per line:

image
image1.jpg
image2.jpg
image3.jpg
image4.jpg