From 4e440b4af6b2de03886b624662de70cd0304ee7f Mon Sep 17 00:00:00 2001
From: Jeongho Nam <samchon.github@gmail.com>
Date: Fri, 5 Jul 2024 17:41:55 +0900
Subject: [PATCH] Add IJsonSchema.IOneOf.discriminator

---
 src/OpenApi.ts                      | 30 +++++++++++++++++++++++++++--
 src/OpenApiV3.ts                    |  7 +++++++
 src/OpenApiV3_1.ts                  |  7 +++++++
 src/internal/SwaggerV2Downgrader.ts |  1 +
 4 files changed, 43 insertions(+), 2 deletions(-)

diff --git a/src/OpenApi.ts b/src/OpenApi.ts
index e90be5f..ac7a25e 100644
--- a/src/OpenApi.ts
+++ b/src/OpenApi.ts
@@ -396,7 +396,7 @@ export namespace OpenApi {
    * Path item.
    *
    * `OpenApi.IPath` represents a path item of emended OpenAPI v3.1,
-   * collecting multiple method operations in a signgle path.
+   * collecting multiple method operations in a single path.
    */
   export interface IPath<
     Schema extends IJsonSchema = IJsonSchema,
@@ -787,7 +787,7 @@ export namespace OpenApi {
     }
 
     /**
-     * Array type.
+     * Array type info.
      */
     export interface IArray<Schema extends IJsonSchema = IJsonSchema>
       extends __ISignificant<"array"> {
@@ -986,6 +986,32 @@ export namespace OpenApi {
        * List of the union types.
        */
       oneOf: Exclude<Schema, IJsonSchema.IOneOf>[];
+
+      /**
+       * Discriminator info of the union type.
+       */
+      discriminator?: IOneOf.IDiscriminator;
+    }
+    export namespace IOneOf {
+      /**
+       * Discriminator info of the union type.
+       */
+      export interface IDiscriminator {
+        /**
+         * Property name for the discriminator.
+         */
+        propertyName: string;
+
+        /**
+         * Mapping of the discriminator value to the schema name.
+         *
+         * This property is valid only for {@link IReference} typed
+         * {@link IOneOf.oneof} elements. Therefore, `key` of `mapping` is
+         * the discriminator value, and `value` of `mapping` is the
+         * schema name like `#/components/schemas/SomeObject`.
+         */
+        mapping?: Record<string, string>;
+      }
     }
 
     /**
diff --git a/src/OpenApiV3.ts b/src/OpenApiV3.ts
index d4a540a..1a84317 100644
--- a/src/OpenApiV3.ts
+++ b/src/OpenApiV3.ts
@@ -251,6 +251,13 @@ export namespace OpenApiV3 {
     }
     export interface IOneOf extends __IAttribute {
       oneOf: IJsonSchema[];
+      discriminator?: IOneOf.IDiscriminator;
+    }
+    export namespace IOneOf {
+      export interface IDiscriminator {
+        propertyName: string;
+        mapping?: Record<string, string>;
+      }
     }
 
     export interface __ISignificant<Type extends string> extends __IAttribute {
diff --git a/src/OpenApiV3_1.ts b/src/OpenApiV3_1.ts
index 070cd38..8b4f2c2 100644
--- a/src/OpenApiV3_1.ts
+++ b/src/OpenApiV3_1.ts
@@ -262,6 +262,13 @@ export namespace OpenApiV3_1 {
     }
     export interface IOneOf extends __IAttribute {
       oneOf: IJsonSchema[];
+      discriminator?: IOneOf.IDiscriminator;
+    }
+    export namespace IOneOf {
+      export interface IDiscriminator {
+        propertyName: string;
+        mapping?: Record<string, string>;
+      }
     }
 
     export interface IArray extends __ISignificant<"array"> {
diff --git a/src/internal/SwaggerV2Downgrader.ts b/src/internal/SwaggerV2Downgrader.ts
index ce73eaf..cb7f389 100644
--- a/src/internal/SwaggerV2Downgrader.ts
+++ b/src/internal/SwaggerV2Downgrader.ts
@@ -291,6 +291,7 @@ export namespace SwaggerV2Downgrader {
             ? { ...union[0] }
             : { "x-oneOf": union.map((u) => ({ ...u, nullable: undefined })) }),
         ...attribute,
+        ...(union.length > 1 ? { discriminator: undefined } : {}),
       };
     };