Added enum custom field names option

README.md

@@ -244,6 +244,35 @@ type Node struct {
 }
 ```
 
+### Custom enum field names
+
+Optionally, enum fields name can be specified by `x-ogen-enum-naming`, for example:
+
+```yaml
+components:
+  schemas:
+    NodeWeight:
+      type: integer
+      enum: [ 1, 3, 5 ]
+      x-ogen-enum-naming:
+        1: Low
+        3: Medium
+        5: High
+```
+
+The generated source code looks like:
+
+```go
+// Ref: #/components/schemas/NodeWeight
+type NodeWeight int
+
+const (
+    Low     NodeWeight = 1
+    Medium  NodeWeight = 3
+    High    NodeWeight = 35
+)
+```
+
 ### Extra struct field tags
 
 Optionally, additional Go struct field tags can be specified by `x-oapi-codegen-extra-tags`, for example:

_testdata/positive/enum_naming.yml

@@ -19,6 +19,8 @@ paths:
                   - PascalStrat
                   - PascalSpecialStrat
                   - PascalExceptionStrat
+                  - CustomNamingStr
+                  - CustomNamingInt
                 properties:
                   VeryBadEnum:
                     $ref: '#/components/schemas/VeryBadEnum'
@@ -28,6 +30,10 @@ paths:
                     $ref: '#/components/schemas/PascalSpecialStrat'
                   PascalExceptionStrat:
                     $ref: '#/components/schemas/PascalExceptionStrat'
+                  CustomNamingStr:
+                    $ref: '#/components/schemas/CustomNamingStr'
+                  CustomNamingInt:
+                    $ref: '#/components/schemas/CustomNamingInt'
 components:
   schemas:
     VeryBadEnum:
@@ -158,3 +164,17 @@ components:
       enum:
         - '1'
         - '-2'
+    CustomNamingStr:
+      type: string
+      enum: [ "a", "b", "e" ]
+      x-ogen-enum-naming:
+        a: Alice
+        b: Bob
+        e: Eve
+    CustomNamingInt:
+      type: integer
+      enum: [ 1, 2, 3 ]
+      x-ogen-enum-naming:
+        1: One
+        2: Two
+        3: Three

gen/_template/schema/enum.tmpl

@@ -42,6 +42,20 @@ func (s *{{ $.Name }}) UnmarshalText(data []byte) error {
 		return errors.Errorf("invalid value: %q", data)
 	}
 }
+
+{{ else -}}
+
+func (s {{ $.Name }}) String() string {
+	switch *s {
+	{{- range $variant := $.EnumVariants }}
+	case {{ $variant.Name }}:
+		return "{{ $variant.Name }}"
+	{{- end }}
+	default:
+		return fmt.Sprintf("UNKNOWN<%v>", *s)
+	}
+}
+
 {{- end }}
 
 {{ end }}

gen/schema_gen_primitive.go

@@ -31,7 +31,8 @@ func (g *schemaGen) enum(name string, t *ir.Type, schema *jsonschema.Schema) (*i
 
 	type namingStrategy int
 	const (
-		pascalName namingStrategy = iota
+		customMapping namingStrategy = iota
+		pascalName
 		pascalSpecialName
 		cleanSuffix
 		indexSuffix
@@ -50,6 +51,14 @@ func (g *schemaGen) enum(name string, t *ir.Type, schema *jsonschema.Schema) (*i
 		}
 
 		switch s {
+		case customMapping:
+			if schema.XOgenEnumNaming == nil {
+				return "", fmt.Errorf("no custom mapping for enum %q", name)
+			}
+			if mappedName, ok := schema.XOgenEnumNaming[vstr]; ok {
+				return mappedName, nil
+			}
+			return "", fmt.Errorf("name '%v' not found in custom mapping for enum %q", vstr, name)
 		case pascalName:
 			return pascal(name, vstr)
 		case pascalSpecialName:
@@ -98,7 +107,7 @@ func (g *schemaGen) enum(name string, t *ir.Type, schema *jsonschema.Schema) (*i
 
 	chosenStrategy, err := func() (namingStrategy, error) {
 	nextStrategy:
-		for strategy := pascalName; strategy < _lastStrategy; strategy++ {
+		for strategy := customMapping; strategy < _lastStrategy; strategy++ {
 			// Treat enum type name as duplicate to prevent collisions.
 			names := map[string]struct{}{
 				name: {},