ciss's sandbox: Field Cardinality

Sets a field form to a fixed amount of items and applies the Required status to all of them.

Warning: This is currently an API-only module, meaning it provides only utility functions without a configurable interface.

Problem

Multiple-valued field forms in Drupal have several limitations:

1. Cardinality is set for the base field, meaning it can't be changed per field instance (this is to allow better handling by field storage backends).
2. Only the first item will be validated as required. It is therefore not possible to have e.g. 4 required field items in a required field.
3. Item offsets are very dynamic: if an item is considered empty, it will be removed and the next item will take its place (i.e. delta value).

This module attempts to tackle each point using the following strategies:

1. Programmatically add additional item forms and add/set required values.
2. Find elements marked as required on the first item and apply them to additional items.
3. No real solution yet, since there is no way to mark a field as "not empty", intercept the removal or reliably determine which offsets got removed. Might require a mapping table and some magic.

Todos

• Reenable sorting
• Handle non-required fields (requires additional mapping table and a lot of magic)
• Provide field ui settings to:
  • Set cardinality
  • Provide per-delta labels and find reliable way to apply them
  • Set required per delta?
• Provide field type to prevent field collections from being tested empty
• Better widget UI?
• Support for inline_entity_form? (very unlikely)
• Define behavior and add tests for:
  • Core fields
  • field_collection
  • entity_translation

Related projects

• Field Instance Cardinality
• Multivalue Settings
• Multiple Value Widget
• Multi Field Fix

Related issues

• #1029298: Allow cardinality to be restricted (overriden and reduced) in the field instance settings
• #1788228: [Meta] Field collection and required or default value fields collected issues and solutions overview