LongType doesn't support incoming String values

[jakobmerrild]

Under the assumption that most consumers of the GraphQL schema specified by Sangria is running in JavaScript it seems prudent to allow input coercion from String for the Long scalar type, as JavaScript has no way of precisely representing the full spectrum using it's number data type.

I.e. given the following schema

type Query {
  echo(number: Long!): Long!
}

then the following payload should be accepted

{
  "query": "query EchoLong($number: Long!) { echo(number: $number) }",
  "operationName": "EchoLong",
  "variables": { "number": "123456" }
}

[yanns]

Thanks for the issue and the PR!
To help me make a decision, do you know if the GraphQL specs mention this?
Are you also aware of how other libraries are handling this?

[jakobmerrild]

According to the latest spec services that specify custom scalars should include the @specifiedBy url, see https://spec.graphql.org/October2021/#sec-Scalars.Custom-Scalars

However, I don't know if Sangria currently supports that annotation?

W.r.t coercion it is up to the implementor to define what are reasonable rules so long as they are performed without losing precision (if I'm reading the spec correctly)

[jakobmerrild]

According to this announcement you can contribute your custom scalars, though given that the announcement is almost 2 years old and there are no new contributions by the community since then, it might not really have taken hold as an idea

[yanns]

Your issue is about input coercion right? https://spec.graphql.org/October2021/#sec-Scalars.Input-Coercion

What you mentioned before is not the same:

Since this coercion behavior is not observable to clients of the GraphQL service, the precise rules of coercion are left to the implementation.

This is for example if the field is a String, and internally it's an Integer, then "the precise rules of coercion are left to the implementation. ".

I assume you're having this issue with a real-world case. Out of curiosity, can you provide more details, like which JavaScript library is used?

[yanns]

Input coercion for the scalar Int do not accept String values:
https://spec.graphql.org/October2021/#sec-Int.Input-Coercion

When expected as an input type, only integer input values are accepted. All other input values, including strings with numeric content, must raise a request error indicating an incorrect type

[jakobmerrild]

We do indeed have issues with a real-world case.
Using sangria 4.3.2 and sangria-circe 1.3.1 on the server and Apollo Client with Typescript on the consumer side we are running into issues because the client generates the Scalar as something that is backed by a string, but the server doesn't accept string values.

[yanns]

I understand your pain, and that there's no easy fix without touching sangria.
But I'll need a bit of time to think about it, as allowing Strings by default does not seem spec compliant.

[jakobmerrild]

Which part of the spec for custom Scalars do you see this breaking? The spec specifically notes that the built-in Int Scalar should only be used for values from -2^32 to 2^32-1 and that values outside this range should be using String or a custom Scalar as not all platforms can handle 64-bit integers, according to the note

[jakobmerrild]

There's also this old issue on the graphql-spec itself. Perhaps the better way forward is to take up the call for a champion and introduce the Long type into the spec now that JavaScript supports BigInt as noted in this comment.

[yanns]

There's also this old issue on the graphql-spec itself. Perhaps the better way forward is to take up the call for a champion and introduce the Long type into the spec now that JavaScript supports BigInt as noted in this comment.

Yes that would be nice.
Do you want to volunteer?

In the meantime, I guess that your point about using string is adequate to this part of the spec yes:

Numeric integer values larger than 32-bit should either use String or a custom-defined Scalar type, as not all platforms and transports support encoding integer numbers larger than 32-bit.

[yanns]

released in https://github.com/sangria-graphql/sangria/releases/tag/v4.2.4