Graphql insert mutation: omitting fields with default values

[andreaiaia]

Hello! I've encountered an issue with the crate: the type generated by the crate from the schema doesn't allow me to omit fields that have a default value generated by the database (for example, a serial id or creation and update timestamps), but it requires me to provide values for them. If I try to give a value of None, Rust sends a query populating the fields as null, and the database returns an error because the fields are not nullable (and I don't want to insert null values anyway).

The following example replicates the mutation I tried to execute using two mock tables that mimic the behavior of the ones I need to manage:

create table hobbies (
    id serial primary key,
    creation_timestamp timestamp with time zone not null default now(),
    username text not null,
    type text not null,
);

I want to run this mutation with Hasura GraphQL:

mutation InsertData(
    $hobbies: [hobbies_insert_input!]!
) {
    insert_hobbies(
        objects: $hobbies
    ) {
        affected_rows
    }
}

With the following input:

{
    "hobbies": [
        {
            "username": "user1",
            "type": "reading"
        },
        {
            "username": "user2",
            "type": "gaming"
        }
    ]
}

Where hobbies_insert_input is defined in the auto-generated schema that I added to the repository files using graphqurl.

When I execute this through Rust, however, I encounter the following problem: the schema forces the type used in Rust to require that I provide a value for all fields in the row, including id, creation_timestamp, and update_timestamp. If I set these fields to None, rust translates them to null, and the database gives me an error because the columns cannot be null. If I omit those values, the compiler does not compile, and manually providing a value when those fields are populated by default by the database doesn't seem like a very elegant solution.

For now the only solution I found was to create a separate module for this mutation and manually create the schema that this module uses.