Fragment spread is possible

Formal Specification

• For each spread (named or inline) defined in the document.
• Let fragment be the target of spread
• Let fragmentType be the type condition of fragment
• Let parentType be the type of the selection set containing spread
• Let applicableTypes be the intersection of GetPossibleTypes ( fragmentType ) and GetPossibleTypes ( parentType )
• applicableTypes must not be empty.

GetPossibleTypes

(

type

)

1. If type is an object type, return a set containing type
2. If type is an interface type, return the set of types implementing type
3. If type is a union type, return the set of possible types of type

Explanatory Text

Fragments are declared on a type and will only apply when the runtime object type matches the type condition. They also are spread within the context of a parent type. A fragment spread is only valid if its type condition could ever apply within the parent type.