Unable to set default values for custom typed strings

[jpalawaga]

Describe the bug
I'm trying to build an enum type that can be used for input. As a part of this, I'd like to be able to set a default value for the enum field as well. I'd like to be able to define this in code (for reuse) rather than as a struct tag (i.e make our actual inputs/outputs match the documentation).

However, when I try to use a custom type with the default struct tags, it seems as though the parser expects a json string/object rather than a string value. You can use a json string to get past this, but then default does something weird. Concrete example below.

To Reproduce

package main_test

import (
	"bytes"
	"context"
	"net/http"
	"net/http/httptest"
	"testing"

	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/swaggest/rest/web"
	"github.com/swaggest/usecase"
)

type Discover string

const (
	DiscoverAll  Discover = "all"
	DiscoverNone Discover = "none"
)

func (d *Discover) Enum() []any {
	return []any{DiscoverAll, DiscoverNone}
}

func TestFoo(t *testing.T) {
	type NewThing struct {
		DiscoverMode *Discover `json:"discover,omitempty" default:"all"`
	}

	s := web.DefaultService()

	s.Post("/foo", usecase.NewInteractor(func(ctx context.Context, input NewThing, output *string) error {
		disc := string(*input.DiscoverMode)
		*output = disc

		return nil
	}))

	req, err := http.NewRequest(http.MethodPost, "/foo", bytes.NewReader([]byte(`{}`)))
	require.NoError(t, err)
	req.Header.Set("Content-Type", "application/json")
	rw := httptest.NewRecorder()

	s.ServeHTTP(rw, req)
	assert.Equal(t, `"all" `, rw.Body.String())
}

Observed behavior

=== RUN   TestFoo
--- FAIL: TestFoo (0.00s)
panic: DiscoverMode: parsing default as JSON: invalid character 'a' looking for beginning of value [recovered]
        panic: DiscoverMode: parsing default as JSON: invalid character 'a' looking for beginning of value

Expected behavior
The API returns all.

Side note: you can change this so it reads default:"\"all\"" -- then the input validation passes, but your default ends up as the quoted json string "all", not all (i.e. it is not possible to produce the valid enum option).

--

I'm happy to make a contribution here if you can point me in the right direction. I did step through the code a bit. I tried Implementing a TextUn/Marshaller so that maybe the type would properly get set as a string in jsonschema-go/reflect.go, but that didn't seem to make anything better on the version I was using. I believe it's because string is added as "a" type, rather than "the" SimpleType, which causes the checkInlineValue to fall into the default rather than String case (where it does a json.Unmarshal)

[vearutop]

Thank you for raising this issue, please try latest version v0.2.64.

I'd like to be able to define this in code (for reuse) rather than as a struct tag (i.e make our actual inputs/outputs match the documentation).

With a new version you should be able to define default on a type using Preparer, Exposer or RawExposer.
https://github.com/swaggest/jsonschema-go?tab=readme-ov-file#implementing-interfaces-on-a-type

[jpalawaga]

Hi @vearutop ! thanks for the quick fix.

In my project, I'm still having a bit of issues with this. The problem lies in the jsonschema-go. Specifically, it seems like there is an issue when the custom type appears as a part of more than one variable definition in the request payload.

What I'm seeing (I apologies I snippet for this yet, I'll try and construct one, but for now I'll describe):

• on the first instance of the custom-typed paramters, we correctly detect its type in reflect().
• then, we do reflectDefer, and cache the reference. keepType is true, so the type is promoted
• then, on the second occurence of the parameter type, we see that we have a cached version so we short circuit. You can see that here: https://github.com/swaggest/jsonschema-go/blob/9575eb9/reflect.go#L497
• but we only take the ref! Which is a mostly empty schema--no associated type!
• we end up paniccing similar to the original issue, since the type isn't selected correctly.

I think the solution is to change the code reference above to pull the cached object from rc.definitions instead of rc.definitionRefss

[jpalawaga]

^ PR open with updated test and code change