By benjifisher on
Change record status: 
Published (View all published change records)
Project: 
Drupal core
Introduced in branch: 
9.2.x
Introduced in version: 
9.2.0
Issue links: 
https://www.drupal.org/node/2882276
Description: 

The callback plugin, part of the Migrate API, can be used to apply a PHP function or class method as one step in a process pipeline. Before Drupal 9.2.0, this plugin was limited to functions or methods with exactly one argument.

As of Drupal 9.2.0, the plugin accepts the optional configuration argument unpack_source. When this argument is set, the value in the process pipeline must be an array and it is interpreted as an argument list.

Before Drupal 9.2.0

process:
  destination_field:
    plugin: callback
    callable: mb_strtolower
    source: source_field

The callback function mb_strtolower() takes one argument.

Starting with Drupal 9.2.0

The above example works as before. With the new unpack_source option, the callback plugin can now use a 2-variable function such as rtrim():

source:
  # plugin ...
  constants:
    slash: /
process:
  field_link_url:
    - plugin: callback
      callable: rtrim
      unpack_source: true
      source:
        - url
        - constants/slash

The callback function rtrim() takes two arguments. This example will remove the trailing /, if any, from the source URL.

Note: This system will also allow calling a function with no arguments by using unpack_source and using an empty array as a source:

process:
  time:
    plugin: callback
    callable: time
    unpack_source: true
    source: {  }
Impacts: 
Module developers
Updates Done (doc team, etc.)
Online documentation: 
Not done
Theming guide: 
Not done
Module developer documentation: 
Not done
Examples project: 
Not done
Coder Review: 
Not done
Coder Upgrade: 
Not done
Other: 
Other updates done

Comments

danflanagan8’s picture

danflanagan8
Primary language English
Location St. Louis, US
commented

This looks good to me. If I had to suggest anything, we could link to the php docs for the two functions that are mentioned: rtrim and mb_strtolower since the details of how those functions accept arguments is of interest.

apotek’s picture

apotek commented

It would be nice to have an idea of how to use multiple arguments to a callback in a chain of plugins. 

destination_field:
  - 
    plugin: some_plugin
    source: my_source_field
  - 
    pluginc: callback
    callback: substr
    unpack_source: true
    source: 
      - ????
      - 0
      - 16

substr() takes three arguments. In this case, one of them would be the output of the previous plugin.

mah ham