Add global headers

src/__test__/trpcToOpenApi.test.ts

@@ -69,6 +69,7 @@ describe("trpcToOpenApi", () => {
           },
         },
       },
+      components: {},
     });
   });
 
@@ -140,6 +141,7 @@ describe("trpcToOpenApi", () => {
           },
         },
       },
+      components: {},
     });
   });
 
@@ -197,4 +199,56 @@ describe("trpcToOpenApi", () => {
       ]);
     });
   });
+
+  describe("globalHeaders", () => {
+    it("includes headers in every endpoint", () => {
+      const t = initTRPC.create();
+      const router = t.router({
+        createThing: t.procedure
+          .input(z.object({ name: z.string() }))
+          .mutation(() => undefined),
+        getThing: t.procedure
+          .input(z.object({ name: z.string() }))
+          .query(() => undefined),
+      });
+
+      const openApiSpec = trpcToOpenApi({
+        apiTitle: "My API",
+        apiVersion: "1.0",
+        basePath: "",
+        router,
+        globalHeaders: {
+          MyHeader: {
+            in: "header",
+            name: "X-My-Header",
+            schema: { type: "string" },
+            required: false,
+          },
+        },
+      });
+
+      expect(openApiSpec.components).toEqual({
+        parameters: {
+          MyHeader: {
+            in: "header",
+            name: "X-My-Header",
+            schema: { type: "string" },
+            required: false,
+          },
+        },
+      });
+
+      const expectedHeaderReferences = [
+        { $ref: "#/components/parameters/MyHeader" },
+      ];
+
+      expect(openApiSpec.paths?.["/createThing"]?.post?.parameters).toEqual(
+        expectedHeaderReferences,
+      );
+
+      expect(
+        openApiSpec.paths?.["/getThing"]?.get?.parameters?.slice(1),
+      ).toEqual(expectedHeaderReferences);
+    });
+  });
 });

src/trpcToOpenApi.ts

@@ -4,7 +4,7 @@ import {
   type ProcedureType,
   type RouterRecord,
 } from "@trpc/server/unstable-core-do-not-import";
-import { type OpenAPIV3, type OpenAPIV3_1 } from "openapi-types";
+import { OpenAPIV3, type OpenAPIV3_1 } from "openapi-types";
 import { type ZodSchema } from "zod";
 import { zodToJsonSchema } from "zod-to-json-schema";
 import { OpenApiMeta } from "./meta.js";
@@ -16,19 +16,32 @@ export function trpcToOpenApi({
   apiVersion,
   basePath,
   router,
+  globalHeaders,
 }: {
   apiTitle: string;
   apiVersion: string;
   basePath: string;
   router: AnyTRPCRouter;
+  globalHeaders?: Record<string, OpenAPIV3_1.ParameterObject>;
 }): OpenAPIV3_1.Document {
+  const headerParameters =
+    globalHeaders != null
+      ? Object.keys(globalHeaders).map(
+          (headerKey): OpenAPIV3_1.ReferenceObject => ({
+            $ref: `#/components/parameters/${headerKey}`,
+          }),
+        )
+      : undefined;
+
   return {
     openapi: "3.1.0",
     info: { title: apiTitle, version: apiVersion },
-    paths: getPathsForRouterRecord(
+    paths: getPathsForRouterRecord({
       basePath,
-      router._def.procedures as RouterRecord,
-    ),
+      routerRecord: router._def.procedures as RouterRecord,
+      additionalParameters: headerParameters,
+    }),
+    components: globalHeaders != null ? { parameters: globalHeaders } : {},
   };
 }
 
@@ -41,10 +54,17 @@ const PROCEDURE_TYPE_HTTP_METHOD_MAP: Record<
   subscription: undefined,
 };
 
-function getPathsForRouterRecord(
-  basePath: string,
-  routerRecord: RouterRecord,
-): OpenAPIV3_1.PathsObject {
+function getPathsForRouterRecord({
+  basePath,
+  routerRecord,
+  additionalParameters,
+}: {
+  basePath: string;
+  routerRecord: RouterRecord;
+  additionalParameters:
+    | (OpenAPIV3_1.ReferenceObject | OpenAPIV3_1.ParameterObject)[]
+    | undefined;
+}): OpenAPIV3_1.PathsObject {
   const paths: OpenAPIV3_1.PathsObject = {};
 
   for (const [procedureName, procedureOrRouterRecord] of entries(
@@ -57,8 +77,13 @@ function getPathsForRouterRecord(
             basePath,
             procedureName: String(procedureName),
             procedure: procedureOrRouterRecord,
+            additionalParameters,
           })
-        : getPathsForRouterRecord(basePath, procedureOrRouterRecord),
+        : getPathsForRouterRecord({
+            basePath,
+            routerRecord: procedureOrRouterRecord,
+            additionalParameters,
+          }),
     );
   }
 
@@ -69,10 +94,14 @@ function getPathsForProcedure({
   basePath,
   procedureName,
   procedure,
+  additionalParameters,
 }: {
   basePath: string;
   procedureName: string;
   procedure: AnyProcedure;
+  additionalParameters:
+    | (OpenAPIV3_1.ReferenceObject | OpenAPIV3_1.ParameterObject)[]
+    | undefined;
 }): OpenAPIV3_1.PathsObject {
   const def = procedure._def as unknown as AnyProcedure["_def"] &
     ProcedureBuilderDef;
@@ -108,6 +137,13 @@ function getPathsForProcedure({
         content,
       };
     }
+
+    if (additionalParameters != null) {
+      operation.parameters = [
+        ...(operation.parameters ?? []),
+        ...(additionalParameters ?? []),
+      ];
+    }
   }
 
   return {