Discrepancy between graphql-js and graphql-jit handling of mutation variables

[gabrielschulhof]

Consider the following code:

const { graphql, parse } = require('graphql')
const { makeExecutableSchema } = require('@graphql-tools/schema')
const { compileQuery } = require('graphql-jit')

const schema = makeExecutableSchema({
  typeDefs: `
  input HelloParams { id1: Int id2: Int }

  type Mutation { hello(params: HelloParams!): String }

  type Query { abc: String }
  `,
  resolvers: {
    Mutation: {
      hello: (_parent, args, _context, _info) => {
        console.log(JSON.stringify(args, null, 4))
        return 'world'
      },
    },
    Query: {
      abc: () => 'def'
    }
  }
})

const source = `mutation myMutation($id1: Int, $id2: Int) {
  hello(params: {id1: $id1, id2: $id2})
}`

const variableValues = {
  id1: 12,
}

const compiledQuery = compileQuery(schema, parse(source))

;(async () => {
  console.log('Begin JIT')
  await compiledQuery.query(undefined, null, variableValues)
  console.log('Begin plain')
  await graphql({ schema, source, variableValues })
  console.log('Done')
})('def')

The parameters passed to the resolver differ as seen from the output:

Begin JIT
{
    "params": {
        "id1": 12,
        "id2": null
    }
}
Begin plain
{
    "params": {
        "id1": 12
    }
}
Done

In particular, graphql-jit adds a null-valued property for a parameter whose corresponding variable is missing, whereas graphql-js omits the property for which the variable is missing. Note that if we pass id1 and id2 as optional parameters to the mutation directly, both graphql-js and graphql-jit will only pass id1 to the resolver.

Thus, it looks like, for a required object-valued parameter whose properties are optional, graphql-jit will pass to the resolver an object with all properties set (nulls for absent properties), whereas graphql-js will pass to the resolver an object with properties omitted for those that are missing values among the variables.

Would it be possible to modify graphql-jit to also strip missing properties the same way that graphql-js does?