View Source Ash.Type.Union (ash v3.4.44)
A union between multiple types, distinguished with a tag or by attempting to validate.
Constraints
:storage
- How the value will be stored when persisted.:type_and_value
will store the type and value in a map like so{type: :type_name, value: the_value}
:map_with_tag
will store the value directly. This only works if all types have atag
andtag_value
configured. Valid values are :type_and_value, :map_with_tag The default value is:type_and_value
.:types
- The types to be unioned, a map of an identifier for the enum value to its configuration.
When usingtag
andtag_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, # The default value is `true` # this passes the tag key/value to the nested type # when casting input cast_tag?: true, tag: :type, tag_value: "my_object" ], other_object: [ type: MyOtherObjectType, cast_tag?: true, tag: :type, tag_value: "my_other_object" ], other_object_without_type: [ type: MyOtherObjectTypeWithoutType, cast_tag?: false, 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 and10
will be the value.