Handle circular dependency in additionalProperties

common/changes/@autorest/modelerfour/fix-additional-props-circular-dep_2021-01-29-18-24.json

@@ -0,0 +1,11 @@
+{
+  "changes": [
+    {
+      "packageName": "@autorest/modelerfour",
+      "comment": "Fix the use of  circular dependencies in additionalProperties [PR #3819](https://github.com/Azure/autorest/pull/3819)",
+      "type": "patch"
+    }
+  ],
+  "packageName": "@autorest/modelerfour",
+  "email": "tiguerin@microsoft.com"
+}

packages/extensions/modelerfour/src/modeler/modelerfour.ts

@@ -712,6 +712,14 @@ export class ModelerFour {
     throw new Error("Method not implemented.");
   }
   processDictionarySchema(name: string, schema: OpenAPI.Schema): DictionarySchema {
+    const dictSchema = new DictionarySchema<any>(
+      this.interpret.getName(name, schema),
+      this.interpret.getDescription("", schema),
+      null,
+    );
+    // cache this now before we accidentally recurse on this type.
+    this.schemaCache.set(schema, dictSchema);
+
     let elementSchema: Schema;
     let elementNullable: boolean | undefined;
     if (schema.additionalProperties === true) {
@@ -727,16 +735,14 @@ export class ModelerFour {
       }
     }
 
-    return this.codeModel.schemas.add(
-      new DictionarySchema(
-        this.interpret.getName(name, schema),
-        this.interpret.getDescription(`Dictionary of <${elementSchema.language.default.name}>`, schema),
-        elementSchema,
-        {
-          nullableItems: elementNullable,
-        },
-      ),
+    dictSchema.language.default.description = this.interpret.getDescription(
+      `Dictionary of <${elementSchema.language.default.name}>`,
+      schema,
     );
+    dictSchema.elementType = elementSchema;
+    dictSchema.nullableItems = elementNullable;
+
+    return this.codeModel.schemas.add(dictSchema);
   }
 
   isSchemaPolymorphic(schema: OpenAPI.Schema | undefined): boolean {
@@ -779,6 +785,7 @@ export class ModelerFour {
     for (const { key: propertyName, value: propertyDeclaration } of items(schema.properties)) {
       const property = this.resolve(propertyDeclaration);
       this.use(<OpenAPI.Refable<OpenAPI.Schema>>propertyDeclaration, (pSchemaName, pSchema) => {
+
         const pType = this.processSchema(pSchemaName || `type·for·${propertyName}`, pSchema);
         const prop = objectSchema.addProperty(
           new Property(

packages/extensions/modelerfour/test/modeler/modelerfour.schemas.test.ts

@@ -0,0 +1,23 @@
+import { addOperation, addSchema, createTestSpec } from "../utils";
+import { runModeler } from "./modelerfour-utils";
+
+describe("Modelerfour.Schemas", () => {
+  describe("additionalProperties", () => {
+    it("support reference to itself(circular dependency", async () => {
+      const spec = createTestSpec();
+
+      addSchema(spec, "SelfRefSchema", {
+        additionalProperties: {
+          $ref: "#/components/schemas/SelfRefSchema",
+        },
+      });
+
+      const codeModel = await runModeler(spec);
+
+      const schema = codeModel.schemas.dictionaries?.[0];
+      expect(schema).not.toBeNull();
+      expect(schema?.language.default.name).toEqual("SelfRefSchema");
+      expect(schema?.elementType).toEqual(schema);
+    });
+  });
+});

packages/extensions/modelerfour/test/modeler/modelerfour.test.ts

@@ -1,3 +1,4 @@
+/* eslint-disable @typescript-eslint/no-non-null-assertion */
 /*---------------------------------------------------------------------------------------------
  *  Copyright (c) Microsoft Corporation. All rights reserved.
  *  Licensed under the MIT License. See License.txt in the project root for license information.