Support single operation parameter

.changeset/breezy-trees-brake.md

@@ -0,0 +1,5 @@
+---
+"openapi-typescript": patch
+---
+
+Support single operation parameter

packages/openapi-typescript/src/transform/operation-object.ts

@@ -1,5 +1,5 @@
 import type { GlobalContext, OperationObject, ParameterObject } from "../types.js";
-import { escObjKey, getEntries, getSchemaObjectComment, indent, tsOptionalProperty, tsReadonly } from "../utils.js";
+import { escObjKey, getEntries, getParametersArray, getSchemaObjectComment, indent, tsOptionalProperty, tsReadonly } from "../utils.js";
 import transformParameterObject from "./parameter-object.js";
 import transformRequestBodyObject from "./request-body-object.js";
 import transformResponseObject from "./response-object.js";
@@ -19,13 +19,14 @@ export default function transformOperationObject(operationObject: OperationObjec
   // parameters
   {
     if (operationObject.parameters) {
+      const parametersArray = getParametersArray(operationObject.parameters);
       const parameterOutput: string[] = [];
       indentLv++;
       for (const paramIn of ["query", "header", "path", "cookie"] as ParameterObject["in"][]) {
         const paramInternalOutput: string[] = [];
         indentLv++;
         let paramInOptional = true;
-        for (const param of operationObject.parameters ?? []) {
+        for (const param of parametersArray) {
           const node: ParameterObject | undefined = "$ref" in param ? ctx.parameters[param.$ref] : param;
           if (node?.in !== paramIn) continue;
           let key = escObjKey(node.name);

packages/openapi-typescript/src/transform/path-item-object.ts

@@ -1,5 +1,5 @@
 import type { GlobalContext, ParameterObject, PathItemObject, ReferenceObject } from "../types.js";
-import { escStr, getSchemaObjectComment, indent } from "../utils.js";
+import { escStr, getParametersArray, getSchemaObjectComment, indent } from "../utils.js";
 import transformOperationObject from "./operation-object.js";
 
 export interface TransformPathItemObjectOptions {
@@ -26,7 +26,7 @@ export default function transformPathItemObject(pathItem: PathItemObject, { path
     const keyedParameters: Record<string, ParameterObject | ReferenceObject> = {};
     if (!("$ref" in operationObject)) {
       // important: OperationObject parameters come last, and will override any conflicts with PathItem parameters
-      for (const parameter of [...(pathItem.parameters ?? []), ...(operationObject.parameters ?? [])]) {
+      for (const parameter of [...(pathItem.parameters ?? []), ...getParametersArray(operationObject.parameters)]) {
         // note: the actual key doesn’t matter here, as long as it can match between PathItem and OperationObject
         keyedParameters["$ref" in parameter ? parameter.$ref : `${parameter.in}/${parameter.name}`] = parameter;
       }

packages/openapi-typescript/src/transform/paths-object.ts

@@ -1,5 +1,5 @@
 import type { GlobalContext, PathsObject, PathItemObject, ParameterObject, ReferenceObject, OperationObject } from "../types.js";
-import { escStr, getEntries, getSchemaObjectComment, indent } from "../utils.js";
+import { escStr, getEntries, getParametersArray, getSchemaObjectComment, indent } from "../utils.js";
 import transformParameterObject from "./parameter-object.js";
 import transformPathItemObject from "./path-item-object.js";
 
@@ -8,7 +8,7 @@ const OPERATIONS = ["get", "post", "put", "delete", "options", "head", "patch",
 function extractPathParams(obj?: ReferenceObject | PathItemObject | OperationObject | undefined): Map<string, ParameterObject> {
   const params = new Map<string, ParameterObject>();
   if (obj && "parameters" in obj) {
-    for (const p of obj.parameters ?? []) {
+    for (const p of getParametersArray(obj.parameters)) {
       if ("in" in p && p.in === "path") params.set(p.name, p);
     }
   }

packages/openapi-typescript/src/types.ts

@@ -196,7 +196,7 @@ export interface OperationObject extends Extensable {
   /** Unique string used to identify the operation. The id MUST be unique among all operations described in the API. The operationId value is case-sensitive. Tools and libraries MAY use the operationId to uniquely identify an operation, therefore, it is RECOMMENDED to follow common programming naming conventions. */
   operationId?: string;
   /** A list of parameters that are applicable for this operation. If a parameter is already defined at the Path Item, the new definition will override it but can never remove it. The list MUST NOT include duplicated parameters. A unique parameter is defined by a combination of a name and location. The list can use the Reference Object to link to parameters that are defined at the OpenAPI Object’s components/parameters. */
-  parameters?: (ParameterObject | ReferenceObject)[];
+  parameters?: ParameterObject | (ParameterObject | ReferenceObject)[];
   /** The request body applicable for this operation. The requestBody is fully supported in HTTP methods where the HTTP 1.1 specification [RFC7231] has explicitly defined semantics for request bodies. In other cases where the HTTP spec is vague (such as GET, HEAD and DELETE), requestBody is permitted but does not have well-defined semantics and SHOULD be avoided if possible. */
   requestBody?: RequestBodyObject | ReferenceObject;
   /** The list of possible responses as they are returned from executing this operation. */

packages/openapi-typescript/src/utils.ts

@@ -2,7 +2,7 @@ import c from "ansi-colors";
 import { isAbsolute } from "node:path";
 import supportsColor from "supports-color";
 import { fetch as unidiciFetch } from "undici";
-import type { Fetch } from "./types.js";
+import type { Fetch, ParameterObject, ReferenceObject } from "./types.js";
 
 // eslint-disable-next-line @typescript-eslint/no-unnecessary-boolean-literal-compare
 if (!supportsColor.stdout || supportsColor.stdout.hasBasic === false) c.enabled = false;
@@ -322,3 +322,7 @@ export function getDefaultFetch(): Fetch {
   }
   return globalFetch;
 }
+
+export function getParametersArray(parameters: ParameterObject | (ParameterObject | ReferenceObject)[] = []): (ParameterObject | ReferenceObject)[] {
+  return Array.isArray(parameters) ? parameters : [parameters];
+}

packages/openapi-typescript/test/operation-object.test.ts

@@ -162,6 +162,42 @@ describe("Operation Object", () => {
       };
     };
   };
+}`);
+  });
+
+  it("handles non-array parameters", () => {
+    const schema: OperationObject = {
+      parameters: {
+        in: "query",
+        name: "search",
+        schema: { type: "string" },
+      },
+      responses: {
+        "200": {
+          description: "OK",
+          content: {
+            "application/json": {
+              schema: { type: "string" },
+            },
+          },
+        },
+      },
+    };
+    const generated = transformOperationObject(schema, options);
+    expect(generated).toBe(`{
+  parameters: {
+    query?: {
+      search?: string;
+    };
+  };
+  responses: {
+    /** @description OK */
+    200: {
+      content: {
+        "application/json": string;
+      };
+    };
+  };
 }`);
   });
 });

packages/openapi-typescript/test/utils.test.ts

@@ -1,4 +1,5 @@
-import { comment, escObjKey, getSchemaObjectComment, parseRef, tsIntersectionOf, tsUnionOf } from "../src/utils.js";
+import { ParameterObject, ReferenceObject } from "../src/types.js";
+import { comment, escObjKey, getParametersArray, getSchemaObjectComment, parseRef, tsIntersectionOf, tsUnionOf } from "../src/utils.js";
 
 describe("utils", () => {
   describe("tsUnionOf", () => {
@@ -167,4 +168,25 @@ describe("utils", () => {
       );
     });
   });
+
+  describe('getParametersArray', () => {
+    it('should return an empty array if no parameters are passed', () => {
+      expect(getParametersArray()).toEqual([]);
+    });
+
+    it('should return an array if a single parameter is passed', () => {
+      const parameter: ParameterObject = { name: 'test', in: 'query' };
+      expect(getParametersArray(parameter)).toEqual([parameter]);
+    });
+
+    it('should return an array if an array of parameters is passed', () => {
+      const parameters: ParameterObject[] = [{ name: 'test', in: 'query' }, { name: 'test2', in: 'query' }];
+      expect(getParametersArray(parameters)).toEqual(parameters);
+    });
+
+    it('should return an array if an array of references is passed', () => {
+      const references: ReferenceObject[] = [{ $ref: 'test' }, { $ref: 'test2' }];
+      expect(getParametersArray(references)).toEqual(references);
+    });
+  });
 });