Add support for const enums

Author: beanjo55

src/openApi/v3/interfaces/JsonCustomVocabulary.d.ts

@@ -0,0 +1,5 @@
+// https://json-schema.org/draft/2020-12/json-schema-core.html#name-non-json-instances
+
+export interface JsonCustomVocabulary {
+    const?: string | number;
+}

src/openApi/v3/interfaces/OpenApiSchema.d.ts

@@ -1,5 +1,6 @@
 import type { Dictionary } from '../../../utils/types';
 import type { WithEnumExtension } from './Extensions/WithEnumExtension';
+import type { JsonCustomVocabulary } from './JsonCustomVocabulary';
 import type { OpenApiDiscriminator } from './OpenApiDiscriminator';
 import type { OpenApiExternalDocs } from './OpenApiExternalDocs';
 import type { OpenApiReference } from './OpenApiReference';
@@ -8,7 +9,7 @@ import type { OpenApiXml } from './OpenApiXml';
 /**
  * https://github.com/OAI/OpenAPI-Specification/blob/master/versions/3.0.2.md#schemaObject
  */
-export interface OpenApiSchema extends OpenApiReference, WithEnumExtension {
+export interface OpenApiSchema extends OpenApiReference, WithEnumExtension, JsonCustomVocabulary {
     title?: string;
     multipleOf?: number;
     maximum?: number;

src/openApi/v3/parser/getModel.ts

@@ -1,3 +1,4 @@
+import { Enum } from '../../../client/interfaces/Enum';
 import type { Model } from '../../../client/interfaces/Model';
 import { getPattern } from '../../../utils/getPattern';
 import type { OpenApi } from '../interfaces/OpenApi';
@@ -8,6 +9,7 @@ import { getModelComposition } from './getModelComposition';
 import { getModelDefault } from './getModelDefault';
 import { getModelProperties } from './getModelProperties';
 import { getType } from './getType';
+import { getOneOfEnum } from './getOneOfEnum';
 
 export const getModel = (
     openApi: OpenApi,
@@ -122,7 +124,22 @@ export const getModel = (
         }
     }
 
-    if (definition.oneOf?.length) {
+    if (
+        definition.oneOf?.length &&
+        (definition.type === 'integer' || definition.type === 'string') &&
+        (typeof definition.oneOf?.at(0)?.const === 'number' || typeof definition.oneOf?.at(0)?.const === 'string')
+    ) {
+        const enumerator: Enum[] = getOneOfEnum(definition.oneOf);
+        if (enumerator.length) {
+            model.export = 'enum';
+            model.type = 'string';
+            model.base = 'string';
+            model.enum.push(...enumerator);
+            model.default = getModelDefault(definition, model);
+
+            return model;
+        }
+    } else if (definition.oneOf?.length) {
         const composition = getModelComposition(openApi, definition, definition.oneOf, 'one-of', getModel);
         model.export = composition.type;
         model.imports.push(...composition.imports);

src/openApi/v3/parser/getOneOfEnum.ts

@@ -0,0 +1,22 @@
+import type { Enum } from '../../../client/interfaces/Enum';
+import { OpenApiSchema } from '../interfaces/OpenApiSchema';
+
+export const getOneOfEnum = (oneOf: OpenApiSchema[]): Enum[] =>
+    oneOf.reduce((enums, item) => {
+        if (typeof item.const === 'number') {
+            enums.push({
+                value: String(item.const),
+                name: `${item.title}` || `'_${item.const}'`,
+                type: 'number',
+                description: item.description || item.title || null,
+            });
+        } else {
+            enums.push({
+                value: `'${item.const}'`,
+                name: `${item.title}` || `'${item.const}'`,
+                type: 'string',
+                description: item.description || item.title || null,
+            });
+        }
+        return enums;
+    }, [] as Enum[]);