return Result from to_output_with of a scalar

[nigimaxx]

Is it possible to implement a scalar that returns a result from its to_output method?

In the end it should look something like this:

#[derive( GraphQLScalar)]
#[graphql(
    name = "Scalar",
    to_output_with = Self::to_output,
    from_input_with = Self::from_input,
   )]
pub struct Scalar(bool);

impl Scalar {
    fn to_output(value: &Scalar) -> Result<String, Err> { ... }

    fn from_input(input: &str) -> Result<Self, Err> { ... }
}

[tyranron]

@nigimaxx no, at the moment, but would you need it? It makes sense that parsing a scalar value on the server side may be fallible. But creating a scalar value on the server side? Its fallibility seems to be an unexpected and undesired situation, which is covered by panicking just fine. For the expected errors, I believe this should be handled outside scalar creation.

[nigimaxx]

@tyranron I'm trying encrypt some value of the scalar.

While it's probably not common, I fell like there are a few possible use cases where the serialization should be fallible. Most likely when using another library.

[tyranron]

@nigimaxx I'm not sure about this. Such serialization error will happen inside juniper without much user control on it. Also, it's not obvious why juniper should be responsible for such internal serialization errors. I would rather split the GraphQL scalar itself and the type that needs serialization into it, providing the TryInto conversion and explicitly returning an error where it's needed. This also has a benefit that the scalar would be serialized once, and not every time it's resolved inside juniper.