Drupal 9 : Migrate D7 body field to paragraph

README.md

1. Run body_to_paragraph migration
2. Run my_node_migration migration

body_to_paragraph.yml

id: body_to_paragraph
class: null
migration_tags:
  - 'Drupal 7'
  - Content
migration_group: paragraphs
label: 'Paragraphs: Blog body to text'

source:
  plugin: d7_node_complete
  node_type: blog  # Your bundle

process:
  field_p_text: body
  # body is the D7 field
  # field_p_text is the D9 paragraph text field

destination:
  plugin: 'entity_reference_revisions:paragraph'
  default_bundle: text # My D9 paragraph bundle

migration_dependencies:
  required: {  }
  optional: {  }

my_node_migration.yml

id: my_node_migration
class: Drupal\node\Plugin\migrate\D7NodeTranslation
migration_tags:
  - 'Drupal 7'
  - Content
migration_group: nodes
label: 'Node complete (blog)'
source:
  plugin: d7_node_complete
  node_type: blog   # My D7/D9 bundle
process:
  nid:
    -
      plugin: get
      source: tnid
      
  # [...] All your regular fields

  #  body: body # Do not migrate body anymore
  
  
  field_paragraphs/target_id:
    -
      plugin: migration_lookup
      migration:
        - body_to_paragraph
      no_stub: true
      source: tnid
    -
      plugin: extract
      index:
        - '0'

  field_paragraphs/target_revision_id:
    -
      plugin: migration_lookup
      migration:
        - body_to_paragraph
      source: tnid
      no_stub: true
    -
      plugin: extract
      index:
        - 1

  field_metatag:
    -
      plugin: d7_metatag_entities
      source: pseudo_metatag_entities

destination:
  plugin: 'entity_complete:node'
  translations: true
  default_bundle: blog

  migration_dependencies:
  required:
    - body_to_paragraph
  optional: {  }