graphene/docs/types/unions.rst
2017-07-26 22:43:22 -07:00

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Unions
======
Union types are very similar to interfaces, but they don't get
to specify any common fields between the types.
The basics:
- Each Union is a Python class that inherits from ``graphene.Union``.
- Unions don't have any fields on it, just links to the possible objecttypes.
Quick example
-------------
This example model defines a ``Character`` interface with a name. ``Human``
and ``Droid`` are two implementations of that interface.
.. code:: python
import graphene
class Human(graphene.ObjectType):
name = graphene.String()
born_in = graphene.String()
class Droid(graphene.ObjectType):
name = graphene.String()
primary_function = graphene.String()
class Starship(graphene.ObjectType):
name = graphene.String()
length = graphene.Int()
class SearchResult(graphene.Union):
class Meta:
types = (Human, Droid, Starship)
Wherever we return a SearchResult type in our schema, we might get a Human, a Droid, or a Starship.
Note that members of a union type need to be concrete object types;
you can't create a union type out of interfaces or other unions.
The above types have the following representation in a schema:
.. code::
type Droid {
name: String
primaryFunction: String
}
type Human {
name: String
bornIn: String
}
type Ship {
name: String
length: Int
}
union SearchResult = Human | Droid | Starship