From 0da326f5d457b1096e5dcc07a0cd994a4c1c1008 Mon Sep 17 00:00:00 2001
From: Michael M <mullinsmikey@users.noreply.github.com>
Date: Fri, 27 Oct 2023 20:11:55 +0200
Subject: [PATCH] feat: add support for explicit discriminators

---
 .../ng-openapi-gen/src/lib/utils/open-api.ts  | 46 +++++++++++++++++++
 .../ng-openapi-gen/src/lib/utils/string.ts    |  2 +-
 2 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/packages/ng-openapi-gen/src/lib/utils/open-api.ts b/packages/ng-openapi-gen/src/lib/utils/open-api.ts
index a63e38b..7cf3a4e 100644
--- a/packages/ng-openapi-gen/src/lib/utils/open-api.ts
+++ b/packages/ng-openapi-gen/src/lib/utils/open-api.ts
@@ -105,6 +105,14 @@ export function tsTypeVal(
         let result = '{\n';
         const properties = schema.properties || {};
         const required = schema.required;
+
+        for (const baseSchema of allOf) {
+            const discriminator = tryGetDiscriminator(baseSchema, schema, openApi);
+            if (discriminator) {
+                result += `'${discriminator.propName}': '${discriminator.value}';\n`;
+            }
+        }
+
         for (const [propName, property] of Object.entries(properties)) {
             if (!property) {
                 continue;
@@ -178,3 +186,41 @@ export function resolveRef(openApi: OpenAPIObject, ref: string): unknown {
     }
     return current;
 }
+
+/** Tries to get a discriminator info from a base schema and for a derived one */
+function tryGetDiscriminator(
+    baseSchemaOrRef: SchemaObject | ReferenceObject,
+    derivedSchema: SchemaObject,
+    openApi: OpenAPIObject,
+) {
+    const baseSchema = (
+        baseSchemaOrRef.$ref ? resolveRef(openApi, baseSchemaOrRef.$ref) : baseSchemaOrRef
+    ) as SchemaObject;
+    const discriminatorProp = baseSchema.discriminator?.propertyName;
+    if (discriminatorProp) {
+        const discriminatorValue = tryGetDiscriminatorValue(baseSchema, derivedSchema, openApi);
+        if (discriminatorValue) {
+            return {
+                propName: discriminatorProp,
+                value: discriminatorValue,
+            };
+        }
+    }
+    return;
+}
+
+/** Tries to get a discriminator value from a base schema and for a derived one */
+function tryGetDiscriminatorValue(
+    baseSchema: SchemaObject,
+    derivedSchema: SchemaObject,
+    openApi: OpenAPIObject,
+): string | null {
+    const mapping = baseSchema.discriminator?.mapping;
+
+    if (mapping) {
+        const mappingIndex = Object.values(mapping).findIndex((ref) => resolveRef(openApi, ref) === derivedSchema);
+        return Object.keys(mapping)[mappingIndex] ?? null;
+    }
+
+    return null;
+}
diff --git a/packages/ng-openapi-gen/src/lib/utils/string.ts b/packages/ng-openapi-gen/src/lib/utils/string.ts
index 2e15750..819ab61 100644
--- a/packages/ng-openapi-gen/src/lib/utils/string.ts
+++ b/packages/ng-openapi-gen/src/lib/utils/string.ts
@@ -66,7 +66,7 @@ export function escapeId(name: string) {
 /** Returns the TypeScript comments for the given schema description, in a given indentation level */
 export function tsComments(description: string | undefined, level: number, deprecated?: boolean): string {
     const indent = '  '.repeat(level);
-    if (description == undefined || description.length === 0) {
+    if (description === undefined || description.length === 0) {
         return indent + (deprecated ? '/** @deprecated */' : '');
     }
     const lines = description.trim().split('\n');