Skip to content

Support unions with multiple mappings pointing to a single underlying type #2071

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

Sign up for GitHub

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
mromaszewicz merged 2 commits into from
Feb 16, 2026
Merged

Support unions with multiple mappings pointing to a single underlying type #2071

Show file tree
Hide file tree
Changes from all commits
Commits
Show all changes
2 commits
Select commit Hold shift + click to select a range
71958af
Support unions with multiple mappings pointing to a single underlying…
tobio Sep 2, 2025
63bcc36
Merge branch 'main' into multi-mapping
tobio Feb 16, 2026
File filter

Filter by extension

Filter by extension
Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
4 changes: 4 additions & 0 deletions internal/test/issues/issue-1530/config.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,4 @@
package: issue1530
generate:
models: true
output: issue1530.gen.go
3 changes: 3 additions & 0 deletions internal/test/issues/issue-1530/doc.go
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,3 @@
package issue1530

//go:generate go run github.com/oapi-codegen/oapi-codegen/v2/cmd/oapi-codegen --config=config.yaml issue1530.yaml
126 changes: 126 additions & 0 deletions internal/test/issues/issue-1530/issue1530.gen.go
View file
Open in desktop

Some generated files are not rendered by default. Learn more about how customized files appear on GitHub.

57 changes: 57 additions & 0 deletions internal/test/issues/issue-1530/issue1530.yaml
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,57 @@
paths:
/config:
post:
summary: Save configuration
requestBody:
content:
application/json:
schema:
$ref: "#/components/schemas/ConfigSaveReq"
responses:
"200":
description: Configuration saved successfully
components:
schemas:
ConfigHttp:
type: object
properties:
config_type:
type: string
host:
type: string
port:
type: integer
user:
type: string
password:
type: string
required:
- config_type
- host
- port
ConfigSaveReq:
oneOf:
- $ref: "#/components/schemas/ConfigHttp"
- $ref: "#/components/schemas/ConfigSsh"
discriminator:
propertyName: config_type
mapping:
ssh_server: "#/components/schemas/ConfigSsh"
apache_server: "#/components/schemas/ConfigHttp"
web_server: "#/components/schemas/ConfigHttp"
another_server: "#/components/schemas/ConfigHttp"
ConfigSsh:
type: object
properties:
config_type:
type: string
host:
type: string
port:
type: integer
user:
type: string
private_key:
type: string
required:
- config_type
51 changes: 51 additions & 0 deletions internal/test/issues/issue-1530/issue1530_test.go
View file
Open in desktop
Original file line number Diff line number Diff line change
@@ -0,0 +1,51 @@
package issue1530_test

import (
"testing"

issue1530 "github.com/oapi-codegen/oapi-codegen/v2/internal/test/issues/issue-1530"
"github.com/stretchr/testify/require"
)

func TestIssue1530(t *testing.T) {
httpConfigTypes := []string{
"another_server",
"apache_server",
"web_server",
}

for _, configType := range httpConfigTypes {
t.Run("http-"+configType, func(t *testing.T) {
saveReq := issue1530.ConfigSaveReq{}
err := saveReq.FromConfigHttp(issue1530.ConfigHttp{
ConfigType: configType,
Host: "example.com",
})
require.NoError(t, err)

cfg, err := saveReq.AsConfigHttp()
require.NoError(t, err)
require.Equal(t, configType, cfg.ConfigType)

cfgByDiscriminator, err := saveReq.ValueByDiscriminator()
require.NoError(t, err)
require.Equal(t, cfg, cfgByDiscriminator)
})
}

t.Run("ssh", func(t *testing.T) {
saveReq := issue1530.ConfigSaveReq{}
err := saveReq.FromConfigSsh(issue1530.ConfigSsh{
ConfigType: "ssh_server",
})
require.NoError(t, err)

cfg, err := saveReq.AsConfigSsh()
require.NoError(t, err)
require.Equal(t, "ssh_server", cfg.ConfigType)

cfgByDiscriminator, err := saveReq.ValueByDiscriminator()
require.NoError(t, err)
require.Equal(t, cfg, cfgByDiscriminator)
})
}
3 changes: 1 addition & 2 deletions pkg/codegen/schema.go
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -938,7 +938,6 @@ func generateUnion(outSchema *Schema, elements openapi3.SchemaRefs, discriminato
if v == element.Ref {
outSchema.Discriminator.Mapping[k] = elementSchema.GoType
mapped = true
break
}
}
// Implicit mapping.
Expand All @@ -949,7 +948,7 @@ func generateUnion(outSchema *Schema, elements openapi3.SchemaRefs, discriminato
outSchema.UnionElements = append(outSchema.UnionElements, UnionElement(elementSchema.GoType))
}

if (outSchema.Discriminator != nil) && len(outSchema.Discriminator.Mapping) != len(elements) {
if (outSchema.Discriminator != nil) && len(outSchema.Discriminator.Mapping) < len(elements) {
return errors.New("discriminator: not all schemas were mapped")
}

Expand Down
37 changes: 21 additions & 16 deletions pkg/codegen/templates/union.tmpl
View file
Open in desktop
Original file line number Diff line number Diff line change
Expand Up @@ -2,6 +2,7 @@
{{$typeName := .TypeName -}}
{{$discriminator := .Schema.Discriminator}}
{{$properties := .Schema.Properties -}}
{{$numberOfUnionTypes := len .Schema.UnionElements -}}
{{range .Schema.UnionElements}}
{{$element := . -}}
// As{{ .Method }} returns the union data inside the {{$typeName}} as a {{.}}
Expand All @@ -14,16 +15,18 @@
// From{{ .Method }} overwrites any union data inside the {{$typeName}} as the provided {{.}}
func (t *{{$typeName}}) From{{ .Method }} (v {{.}}) error {
{{if $discriminator -}}
{{range $value, $type := $discriminator.Mapping -}}
{{if eq $type $element -}}
{{$hasProperty := false -}}
{{range $properties -}}
{{if eq .GoFieldName $discriminator.PropertyName -}}
t.{{$discriminator.PropertyName}} = "{{$value}}"
{{$hasProperty = true -}}
{{if eq $numberOfUnionTypes (len $discriminator.Mapping) -}}
{{range $value, $type := $discriminator.Mapping -}}
{{if eq $type $element -}}
{{$hasProperty := false -}}
{{range $properties -}}
{{if eq .GoFieldName $discriminator.PropertyName -}}
t.{{$discriminator.PropertyName}} = "{{$value}}"
{{$hasProperty = true -}}
{{end -}}
{{end -}}
{{if not $hasProperty}}v.{{$discriminator.PropertyName}} = "{{$value}}"{{end}}
{{end -}}
{{if not $hasProperty}}v.{{$discriminator.PropertyName}} = "{{$value}}"{{end}}
{{end -}}
{{end -}}
{{end -}}
Expand All @@ -35,16 +38,18 @@
// Merge{{ .Method }} performs a merge with any union data inside the {{$typeName}}, using the provided {{.}}
func (t *{{$typeName}}) Merge{{ .Method }} (v {{.}}) error {
{{if $discriminator -}}
{{range $value, $type := $discriminator.Mapping -}}
{{if eq $type $element -}}
{{$hasProperty := false -}}
{{range $properties -}}
{{if eq .GoFieldName $discriminator.PropertyName -}}
t.{{$discriminator.PropertyName}} = "{{$value}}"
{{$hasProperty = true -}}
{{if eq $numberOfUnionTypes (len $discriminator.Mapping) -}}
{{range $value, $type := $discriminator.Mapping -}}
{{if eq $type $element -}}
{{$hasProperty := false -}}
{{range $properties -}}
{{if eq .GoFieldName $discriminator.PropertyName -}}
t.{{$discriminator.PropertyName}} = "{{$value}}"
{{$hasProperty = true -}}
{{end -}}
{{end -}}
{{if not $hasProperty}}v.{{$discriminator.PropertyName}} = "{{$value}}"{{end}}
{{end -}}
{{if not $hasProperty}}v.{{$discriminator.PropertyName}} = "{{$value}}"{{end}}
{{end -}}
{{end -}}
{{end -}}
Expand Down