How to implement GraphQL Scalar for MongoDB sort property found in collection.find() function of MongoDB's? - graphql-js

Question

I'm trying to create an argument type using type-graphql to accept arguments through the GraphQL query. The sort I'm talking about is a property of the options found on MongoDB's native NodeJS driver documentation.
#ArgsType()
export class FindAllArgs implements FindOneOptions {
#Field(type => Int, { defaultValue: 0, description: 'Sets the limit of documents returned in the query.' })
#Min(0)
limit?: number;
// This is where the custom sort would go about.
#Field(type => SortScalar)
sort?: sortScalar;
#Field(type => Int, { defaultValue: 0, description: 'Set to skip N documents ahead in your query (useful for pagination).' })
#Min(0)
skip?: number;
}
As you can see, simple types are fine, but when it comes to something like the sort object, I'm not sure how to go on about it.
NestJS implements a date scalar like so:
import { Scalar, CustomScalar } from '#nestjs/graphql';
import { Kind, ValueNode } from 'graphql';
#Scalar('Date', type => Date)
export class DateScalar implements CustomScalar<number, Date> {
description = 'Date custom scalar type';
parseValue(value: number): Date {
return new Date(value); // value from the client
}
serialize(value: Date): number {
return value.getTime(); // value sent to the client
}
parseLiteral(ast: ValueNode): Date {
if (ast.kind === Kind.INT) {
return new Date(ast.value);
}
return null;
}
}
Even in the example, it uses a returnTypeFunction #Scalar('Date', type => Date). What am I supposed to replace Date with? What do I put in for parseValue, serialize, and parseLiteral?

Answer 1

You can just use #InputType to nest objects in args - you don't need scalars for that, they are designed only for serializable things like timestamp -> number, mongo id -> ObjectId instance, etc.