3.1 KiB
| title | summary |
|---|---|
| Enums, unions, and interfaces | Add some non-object types to your schema |
Working with generic types
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Enums, unions, and interfaces
In more complex schemas, you may want to define types that aren't simply a list of fields, or "object types." These include enums, unions and interfaces.
Enum types
Enum types are simply a list of string values that are possible for a given field. They are
often used in arguments to queries, such as {sort: DESC }.
It's very easy to add enum types to your schema. Just use the enums section of the config.
app/_graphql/schema.yml
enums:
SortDirection:
values:
DESC: Descending order
ASC: Ascending order
Interfaces
An interface is a specification of fields that must be included on a type that implements it.
For example, an interface Person could include firstName: String, surname: String, and
age: Int. The types Actor and Chef would implement the Person interface. Actors and
chefs must have names and ages.
To define an interface, use the interfaces section of the config.
app/_graphql/schema.yml
interfaces:
Person:
fields:
firstName: String!
surname: String!
age: Int!
resolveType: [ 'MyProject\MyResolver', 'resolvePersonType' ]
Interfaces must define a resolveType resolver method to inform the interface
which type it is applied to given a specific result. This method is non-discoverable and
must be applied explicitly.
public static function resolvePersonType($object): string
{
if ($object instanceof Actor) {
return 'Actor';
}
if ($object instanceof Chef) {
return 'Chef';
}
}
Union types
A union type is used when a field can resolve to multiple types. For example, a query for "Articles" could return a list containing both "Blog" and "NewsStory" types.
To add a union type, use the unions section of the configuration.
app/_graphql/schema.yml
unions:
Article:
types: [ 'Blog', 'NewsStory' ]
typeResolver: [ 'MyProject\MyResolver', 'resolveArticleUnion' ]
Like interfaces, unions need to know how to resolve their types. These methods are also non-discoverable and must be applied explicitly.
public static function resolveArticleUnion(Article $object): string
{
if ($object->category === 'blogs')
return 'Blog';
}
if ($object->category === 'news') {
return 'NewsStory';
}
}
Further reading
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