> ## Documentation Index
> Fetch the complete documentation index at: https://helix-claude-document-return-objects-rxi6v.mintlify.site/llms.txt
> Use this file to discover all available pages before exploring further.

# E209

# Unknown Type for Parameter

## Erroneous Code Example

This error occurs when you specify an unknown type for a query parameter that is not a primitive type or a type defined in your schema.

<CodeGroup>
  ```helixql queries.hx theme={null}
  QUERY getItem(data: UnknownType) =>
      RETURN data
  ```

  ```helixql schema.hx theme={null}
  N::User {
      name: String,
  }
  ```
</CodeGroup>

## Solution

Use a primitive type (String, I32, U32, F64, Bool, ID, etc.) or declare the type in your schema.

<CodeGroup>
  ```helixql queries.hx theme={null}
  QUERY getUser(id: ID) =>
      user <- N<User>(id)
      RETURN user
  ```

  ```helixql schema.hx theme={null}
  N::User {
      name: String,
  }
  ```
</CodeGroup>