View Source Ash.Type.Union (ash v2.9.20)

A union between multiple types, distinguished with a tag or by attempting to validate.

constraints
Constraints

:types - The types to be unioned, a map of an identifier for the enum value to its configuration.
When using tag and tag_value we are referring to a map key that must equal a certain value in order for the value to be considered an instance of that type.
For example:
```
types:  [
  int: [
    type: :integer,
    constraints: [
      max: 10
    ]
  ],
  object: [
    type: MyObjectType,
    tag: :type,
    tag_value: "my_object"
  ],
  other_object: [
    type: MyOtherObjectType,
    tag: :type,
    tag_value: "my_other_object"
  ],
  other_object_without_type: [
    type: MyOtherObjectTypeWithoutType,
    tag: :type,
    tag_value: nil
  ]
]  
```
IMPORTANT:
This is stored as a map under the hood. Filters over the data will need to take this into account.
Additionally, if you are not using a tag, a value will be considered to be of the given type if it successfully casts. This means that, for example, if you try to cast "10" as a union of a string and an integer, it will end up as "10" because it is a string. If you put the integer type ahead of the string type, it will cast first and 10 will be the value.