feat: add path variable decorator

Co-authored-by: imdudu1 <[email protected]>

Author: jbl428

lib/decorators/constants.ts

@@ -1,2 +1,3 @@
 export const HTTP_INTERFACE_METADATA = Symbol("HTTP_INTERFACE_METADATA");
 export const HTTP_EXCHANGE_METADATA = Symbol("HTTP_EXCHANGE_METADATA");
+export const PATH_VARIABLE_METADATA = Symbol("PATH_VARIABLE_METADATA");

lib/decorators/path-variable.decorator.spec.ts

@@ -0,0 +1,32 @@
+import { describe, test, expect } from "vitest";
+import { PATH_VARIABLE_METADATA } from "./constants";
+import {
+  PathVariable,
+  type PathVariableMetadata,
+} from "./path-variable.decorator";
+
+describe("PathVariable", () => {
+  test("should set path variable metadata", () => {
+    // given
+    class TestService {
+      request(
+        @PathVariable("foo") foo: string,
+        @PathVariable("bar") bar: string
+      ): string {
+        return foo + bar;
+      }
+    }
+
+    // when
+    const result: PathVariableMetadata = Reflect.getMetadata(
+      PATH_VARIABLE_METADATA,
+      TestService.prototype,
+      "request"
+    );
+
+    // then
+    expect(result).toHaveLength(2);
+    expect(result.get(0)).toBe("foo");
+    expect(result.get(1)).toBe("bar");
+  });
+});

lib/decorators/path-variable.decorator.ts

@@ -0,0 +1,24 @@
+import { PATH_VARIABLE_METADATA } from "./constants";
+
+export type PathVariableMetadata = Map<number, string>;
+
+export function PathVariable(name: string): ParameterDecorator {
+  return (target, propertyKey, parameterIndex) => {
+    if (typeof propertyKey === "undefined") {
+      return;
+    }
+
+    const metadata: PathVariableMetadata =
+      Reflect.getMetadata(PATH_VARIABLE_METADATA, target, propertyKey) ??
+      new Map();
+
+    metadata.set(parameterIndex, name);
+
+    Reflect.defineMetadata(
+      PATH_VARIABLE_METADATA,
+      metadata,
+      target,
+      propertyKey
+    );
+  };
+}