I'm getting this error when trying to query a type and a descendant:
"Fragment cannot be spread here as objects of type \"AppTestObject\" can never be of type \"AppTestChild\"."
I set up a test install using recipe-core, admin, graphql, and graphql-devtools (all latest) to test this out in a basic setting. I've created 2 objects:
class TestObject extends DataObject {
private static $singular_name = "Test Object";
private static $plural_name = "Test Objects";
private static $table_name = "TestObject";
private static $db = [
'Title' => 'Varchar(255)'
];
}
class TestChild extends DataObject {
private static $singular_name = "Test Child";
private static $plural_name = "Test Children";
private static $table_name = "TestChild";
private static $db = [
'Title' => 'Varchar(255)'
];
}
And set up simple scaffolding through configuration:
SilverStripe\GraphQL\Controller:
schema:
scaffolding:
types:
App\TestObject:
fields: [ID]
operations:
read: true
App\TestChild:
fields: [ID, Title]
operations:
read: true
I'm able to query each of these types individually without any problems. But when I try to get TestChild as a descendant of TestObject I get the error above. Here's an example of my query:
query {
readAppTestObjects {
edges {
node {
...on AppTestChild {
Title
}
}
}
}
}
Checking the documentation for the schema in graphiql, there is nothing under readAppTestObjects referencing descendants, although in the documentation for silverstripe/graphql it says:
When reading types that have exposed descendants (e.g. reading Page, when RedirectorPage is also exposed), the return type is a union of the base type and all exposed descendants. This union type takes on the name {BaseType}WithDescendants.
