Improve argument passing to fields

I like the idea, should definitely simplify both the field handlers and the mapping calls. I like #1 best - too late for V2.2, but let's get this into V2.3.

This is an important prerequisite for #1240928: META: Refactoring of file destination/field handlers.

I am working on an Address Field myself, and am excited to see that Migrate 7.x-2.3 was released 2012-Mar-13.

What is the status of this?

The main initiative for Migrate 2.4 is improving the file handling, and this is the first step. With Drupalcon followed by a short vacation, I won't have much time in the next couple of weeks, but in the meantime let's discuss how this should be approached here. What would be the best DX for migrating to multi-component fields like files? As I said previously, I prefer @drewish's first proposal, but I'm open to other arguments or new suggestions.

Is it possible to use default values for arguments, like defaultValue() for fields?

Not with the current argument-based method, no. But the nice thing about drewish's proposal in #1 is that each subfield would have its own field mapping, so all the field mapping methods like defaultValue and sourceMigration would be available to them.

I've added an Address Field example to the docs:

http://drupal.org/node/1412126

Mainly because it is a more in-depth example than body_summary (more attributes to consider, and the use of Country as the base field is perhaps confusing to some).

Removing my long comment, I started a new issue: #1509750: Trying to map subfields (file field description) to a multi-value file field

Thanks drewish :) I simply don't know how to solve the problem at all currently without some sort of change to how to pass in arguments.

The problem I'm having is how to migrate into a multi-value file field, while keeping the Description for each one? In my example above I show how I can do either multi-value without the description, and also single value and keep the description. How can I do both?

Hopefully 2.4 provides a good solution for this.

Started a new issue for this: #1509750: Trying to map subfields (file field description) to a multi-value file field

OK, the simplest way to implement this in an upwardly-compatible way was to populate the arguments array. This doesn't address multiple values yet - the field handlers will need to change to handle that, but it's a start...

Committed to D6 and D7. I modified the text field handler to be able to handle arrays, which it couldn't before. E.g.

  $this->addFieldMapping('field_multi_text', 'multi_body');
  $this->addFieldMapping('field_multi_text:summary', 'multi_teaser');
...
  public function prepareRow($row) {
    $result = db_select('source_table', 't')
                   ->fields('t', array('body', 'teaser'))
                   ->condition('id', $row->id)
                   ->execute();
    foreach ($result as $body_row) {
      $row->multi_body[] = $body_row->body;
      $row->multi_teaser[] = $body_row->teaser;
    }
  }

Should ensure that each instance of the text field gets its own summary.

I did not modify the file field handler to deal with arrays for alt/title/etc. - I figure that stuff is going to get completely refactored anyway...

So if i was doing something like

    // Copy an image file, write DB record to files table, and save in Field storage.
    $arguments = MigrateFileFieldHandler::arguments(IMPORT_FEED_BASE_URL,
      'file_copy', FILE_EXISTS_RENAME, NULL, array());
    $this->addFieldMapping('field_op_main_image', 'image')
         ->arguments($arguments)
         ->xpath('/article/image');

What should the arguments be now?

I get Call to undefined method MigrateFileFieldHandler::arguments()

Can we please document and give a little more information to us unfortunate noobs that find functions we were using mysteriously missing

See http://drupal.org/node/1540106 - when you upgraded and ran update.php, it should have given you a link to the documentation.

OK, looks like (correct me if i'm wrong) but you can pass your arguments like this

    $this->addFieldMapping('field_op_main_image', 'image')
         ->xpath('/article/image');

    $this->addFieldMapping('field_op_main_image:file_replace')
         ->defaultValue(FILE_EXISTS_REPLACE);