Serialize queries into GraphQL

[Bobrokus]

I suggest adding a way to serialize queries into their original GraphQL code.

You can serialize an Operation but that requires building the query. This is a problem when the query accepts variables and overall adds unnecessary overhead.

In my case I have a BulkOperationRunMutation which runs a mutation in bulk. This query accepts mutation: String, the actual mutation that will be run, and a file with variables that will be passed to each instance of the mutation in Jsonl format.
My idea is to create a wrapper that takes in a QueryFragment, serializes it into a string, and passes it to BulkOperationRunMutation as the mutation argument.

Example:

Serialize this

#[derive(cynic::QueryVariables, Debug)]
pub struct DeleteProductVariables<'a> {
    pub input: ProductDeleteInput<'a>,
}

#[derive(cynic::QueryFragment, Debug)]
#[cynic(graphql_type = "Mutation", variables = "DeleteProductVariables")]
pub struct DeleteProduct {
    #[arguments(input: $input)]
    pub product_delete: Option<ProductDeletePayload>,
}

#[derive(cynic::QueryFragment, Debug)]
pub struct ProductDeletePayload {
    pub deleted_product_id: Option<cynic::Id>,
}

#[derive(cynic::InputObject, Debug)]
pub struct ProductDeleteInput<'a> {
    pub id: &'a cynic::Id,
}

into

mutation deleteProduct($input: ProductDeleteInput!) {
  productDelete(input: $input) {
    deletedProductId
  }
}

[Bobrokus]

✅ Implemented as cynic::queries::build_executable_document. See #1004