Dynamic Default and Allowed Values for List Fields in Drupal 8 or 9 or 10

By hari, 2 November, 2022

let’s suppose that there is an Alignment field (field_alignment), that had “Left” and “Right” as options. However, the Article content type was added, and it needed a “Center” alignment option, while the other content types needed to only have the original options. Additionally, existing content defaults to “Right” alignment, but the Article content type should use “Center” as the default value.

With that in mind, let’s walk through how to do this in Drupal using the allowed_values_function and default_value_callback field configuration values.

Allowed Values

First we will alter our allowed values to add “Center” as an alignment option for Article content.

In the field instance definition configuration file, set the allowed_values_function key. Note that the allowed_values entries can be removed once an allowed_values_function is in place.

field.storage.node.field_alignment.yml

Now setup the allowed values function and place it anywhere in the global namespace (e.g. a .module file):

Once the function is in place, the UI will reflect the change and disable manual editing of the allowed options.

field configuration

 

Default Values

 

Now we will leverage our newly added “Center” alignment option and set it as the default value for this field when authoring Article content.

In the field base definition configuration file, set the default_value_callback.

field.field.node.article.field_alignment.yml

Next, setup the default value function anywhere in the global namespace as follows:

Reference

With all of this in place, re-import the configuration and test it out. The authoring interface should now reflect the alternate allowed values per content type as well as the custom default value. So the next time the List field doesn’t quite meet your needs, give it a second chance, it might just be the right field for the job!

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