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Add optional type generation for inline schemas #2366

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68abea9
Add optional type generation for inline schemas
mromaszewicz May 4, 2026
f6c3b31
Update internal/test/anonymous_inner_hoisting/global/spec.yaml
mromaszewicz May 4, 2026
107232d
Update hoisted typedef comment
mromaszewicz May 4, 2026
68c3d9c
Merge remote-tracking branch 'origin/main' into fix/issue-1139
mromaszewicz May 4, 2026
476b896
Revert "Update hoisted typedef comment"
mromaszewicz May 4, 2026
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5 changes: 5 additions & 0 deletions configuration-schema.json
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Original file line number Diff line number Diff line change
Expand Up @@ -277,6 +277,11 @@
"description": "When set to true, automatically renames types that collide across different OpenAPI component sections (schemas, parameters, requestBodies, responses, headers) by appending a suffix based on the component section. Also detects collisions between component types and client response wrapper types. Without this, the codegen will error on duplicate type names, requiring manual resolution via x-go-name.",
"default": false
},
"generate-types-for-anonymous-schemas": {
"type": "boolean",
"description": "When true, every inline schema that would otherwise generate as an anonymous Go struct is instead emitted as a named type with a path-derived name (e.g. `GetRolesIdResponseBody_Data`). Equivalent to adding `x-go-type-name` to every inline schema; when both are present at the same site, `x-go-type-name` wins. Default false. See https://github.com/oapi-codegen/oapi-codegen/issues/1139",
"default": false
},
"type-mapping": {
"type": "object",
"additionalProperties": false,
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7 changes: 7 additions & 0 deletions internal/test/anonymous_inner_hoisting/global/cfg.yaml
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Original file line number Diff line number Diff line change
@@ -0,0 +1,7 @@
package: global
output: client.gen.go
generate:
models: true
client: true
output-options:
generate-types-for-anonymous-schemas: true

@jamietanna jamietanna May 4, 2026

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IMO, I'd prefer this by default - most folks don't control their specs, and so they get anonymous structs used which can be awkward

I'd personally swap this with a compatibility-options to disable this functionality

Using an OpenAPI Overlay is one way to get around this, but managing all areas this may apply will be quite hard

@mromaszewicz mromaszewicz May 4, 2026

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I have the opposite view.

In specs with lots of inline schemas, this positively litters the file with new type definitions, and in many cases, you don't need to ever refer to the type, so the code, IMO, is nicer. I'm open to defaulting it to be on, however, I dislike the output.

Whenever you have an inline schema in a request body, or a parameter, you will never need to create an instance of that type, deserialization does that for you.

The place where it is nice to have is when you have inline schemas in things you are constructing; usually response bodies, and in those cases, it's so much nicer to declare those specifically. I realize that some people don't control their specs.

279 changes: 279 additions & 0 deletions internal/test/anonymous_inner_hoisting/global/client.gen.go
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44 changes: 44 additions & 0 deletions internal/test/anonymous_inner_hoisting/global/client_test.go
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@@ -0,0 +1,44 @@
package global

import (
"encoding/json"
"testing"

"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)

// TestHoistedTypesExist verifies that with output-options.generate-types-for-
// anonymous-schemas enabled, the inline schemas in spec.yaml become named
// Go types we can reference directly. The spec is the canonical issue #1139
// shape: a response body using `allOf` to merge a $ref with sibling
// `properties:` containing an inline `data` object.
func TestHoistedTypesExist(t *testing.T) {
// Both the response root and the nested inline `data` schema should be
// emitted as named types — assigning a typed zero value would not
// compile if either were still anonymous structs.
var responseBody GetRolesId200JSONResponseBody
var dataField GetRolesId200JSONResponseBody_Data

// Field-level type identity: GetRolesId200JSONResponseBody.Data must be
// of the hoisted GetRolesId200JSONResponseBody_Data type. This
// assignment fails to compile if Data is still an anonymous struct.
responseBody.Data = dataField
_ = responseBody
}

func TestHoistedTypesRoundTrip(t *testing.T) {
body := GetRolesId200JSONResponseBody{
Data: GetRolesId200JSONResponseBody_Data{
Role: Role{Id: 7, Name: "admin"},
},
Ok: true,
}

encoded, err := json.Marshal(body)
require.NoError(t, err)

var decoded GetRolesId200JSONResponseBody
require.NoError(t, json.Unmarshal(encoded, &decoded))
assert.Equal(t, body, decoded)
}
2 changes: 1 addition & 1 deletion ...test/anonymous_inner_hoisting/generate.go → ...onymous_inner_hoisting/global/generate.go
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@@ -1,3 +1,3 @@
package anonymous_inner_hoisting
package global

//go:generate go run github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen --config=cfg.yaml spec.yaml
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