midGraphQL
What are Input Object Types?
Updated Apr 28, 2026
Short answer
Input Types are special object types used strictly for passing complex hierarchical data as arguments to queries and mutations.
Deep explanation
You cannot pass standard Object types as arguments because they might contain interfaces or circular references, which are invalid for inputs. Input types are defined with the input keyword and only contain scalars, enums, or other input types.
Real-world example
Submitting a large, deeply nested form (like a shipping address and billing details) to a mutation in a single variable.
Common mistakes
- Trying to use a regular `type` as an argument to a mutation, which will throw a schema validation error.
Follow-up questions
- Can Input types have circular references?