fix #2524 basic alias Byte was not binded properly

[mstephano]

Issue from v0.17.24+ with binding bytes type

Fixes #2524 for basic alias Byte (proposition from @roneli). Also added tests to make sure binding works properly for:

• basic alias Rune
• defined type for []byte
• defined type for []rune

I have:

• Added tests covering the bug / feature (see testing)
• Updated any relevant documentation (see docs)

[coveralls]

Coverage: 75.517% (-0.9%) from 76.375% when pulling 705d919 on mstephano:fix/byte into e6114a2 on 99designs:master.

[mstephano]

Should I add some integration tests too to increase the coverage?

[roneli]

Looks great, will add as per my comment if we define something like this:

scalar StringMap

type SomeStruct {
  field: StringMap
}

func MarshalStrMap(val map[string]string) graphql.Marshaler {
	return graphql.WriterFunc(func(w io.Writer) {
		err := json.NewEncoder(w).Encode(val)
		if err != nil {
			panic(err)
		}
	})
}

func UnmarshalStrMap(v interface{}) (map[string]string, error) {
	if m, ok := v.(map[string]string); ok {
		return m, nil
	}

	return nil, fmt.Errorf("%T is not a map", v)
}

And we have a struct that is

type NamedStringType string

type SomeStruct struct{
   Field map[string]NamedStringType
}

The generated go will try to use the unrmarshal of the string map but it won't work, since we need to convert the named type to pass to the unmarshaler.

I am trying to figure out in the generator template how to check and fix it.

We can maybe do this in a different PR / I will open an issue about this later today.

[mstephano]

@roneli I just tried your code, can you replace map[string]string by map[string]NamedStringType in your marshal/unmarshal func and let me know if that works.

[roneli]

@roneli I just tried your code, can you replace map[string]string by map[string]NamedStringType in your marshal/unmarshal func and let me know if that works.

Yes that will work, but then I need to create an un/marshal for every named type. What I did was force a resolver on the field and convert there. Basically this error will occur if its an external map and you auto bind. (I am doing a lot of auto binding with many many go structs). In that case my simple StringMap isn't enough and I need to create a special map per type.

[mstephano]

@roneli Can you create a new issue for the map and describe the improvement you need with code example? I will take a look into it and we can keep our conversation there.

This PR is really to fix for Byte for anyone who use it.

[StevenACoffman]

Thanks for the fix, and I really appreciate you continuing to work on these issues!