Why does the File interface not extend the Node interface in GraphQL?

Shopify Apps
1

Dear Shopify Community,

whilest using the GraphiQL browser I stumbled upon an strange inconsistency and I hope somebody can help me understand why this is and if this is intended behavior:

The File interface does not extend the Node interface [see API ref.]

but querying node(id:__){…} I can use the polymorphism ‘selector’ with __typename … on File{…}

this is not a very drastic issue but still a bit strage.

Hope someone knows why : )

Best regards,

Marco

2

Hello @MarcoDiRich
Yes, you are correct. The File interface in GraphQL does not extend the Node interface. However, when using the node(id: __) query in GraphQL, you can still utilize the polymorphism feature by using the __typename field to differentiate between different types, including the File type.

The __typename field is a special field in GraphQL that allows you to retrieve the type name of a queried object. By using it in conjunction with the ... on TypeName syntax, you can conditionally specify the fields you want to retrieve based on the type of the object.

Here’s an example of how you can use the polymorphism and __typename with the File type:

query {
node(id: "file_id") {
__typename
... on File {
id
filename
size
# Other File-specific fields you want to retrieve
}
}
}

In this example, you are querying the node with a specific file_id. The __typename field allows you to determine if the returned object is of type File. If it is, you can include the relevant fields specific to the File type, such as id, filename, and size.

By leveraging the __typename field and conditional fragments (... on TypeName), you can handle different types of objects in your GraphQL queries and retrieve the appropriate fields based on their types.

query {
  node(id: "file_id") {
    __typename
    ... on File {
      id
      filename
      size
      # Other File-specific fields you want to retrieve
    }
  }
}

Thank You