Migrate to Drupal 7

Migrate Module

• Powerful object oriented framework for moving content into Drupal.

• Minimal UI, primarily code based.

• Migrate Extras provides support for many contrib modules

• The best documentation is in the wine.inc and beer.inc example code.

• Migrate is faster, and more flexible but you need to write code to map fields.

• Feeds doesn't work well if you've got different content types that need to reference each other.

Main Concepts:-

1. Source.
2. Destination
3. Map
4. Field mapping.
5. Field Handling.
6. Migration

Source:

• Interface to your existing data (SQL, CSV, XML, JSON).
• Provides a list of fields and descriptions.
• Iterates (reset, next) over rows.
• 
  

Destination:

• Interface for writing data to Drupal— typically to a Entity.
• Creates one record for each record in the source. If you’re creating users and profiles, you’ll need two migrations.

Map:

Source:-

destination:-

Mapping of source and Destination in database:

• Connects the source’s ID to the destination’s ID.
• Provides lookup facilities.
• Allows created items to be deleted as part of a rollback.
• 
  

Field Mapping:-

Source:-

Destination:-

Field mapping from source to Destination:-

• Links a source field to a destination field.
• Lets you look up IDs from the other migration’s maps with sourceMigration().
• If the destination has a complex structure (e.g. Address or file field) then additional data is passed in via arguments().

Migration:

• Code that glues the parts together
• In your constructor you setup: source, destination, map and field mappings
• Allows customization at several points: prepareRow(), prepare(), complete().

Field Handling:-

• Handles the details of converting the field into the structure that Drupal understands.
• Turns $entity->field_bar = “foo” into                                                                                        $entity->field_bar[‘und’][0][‘value’] = “foo”.
• Might pull additional data out of arguments.
• 
  

  Destination Handling:-

• Provides additional functionality to an existing destination, e.g. comment adding a field to nodes for comment status.
• Destination delegates calls to fields(), prepare(), complete() to the destination handlers.
• You probably won’t need to write one.