Merge pull request #8 from pfrazee/master

Add CustomError responses

Author: timonson

README.md

@@ -33,6 +33,26 @@ for await (const req of server) {
 }
 ```
 
+#### custom errors
+
+Throw a `CustomError` to send a server-defined error response.
+
+```typescript
+import { CustomError, respond } from "https://deno.land/x/gentle_rpc/mod.ts";
+
+//..
+await respond({
+  throwError: () => {
+    throw new CustomError(
+      -32000, // the JSON-RPC error code. Note, must be -32000 to -32099
+      "An error occurred", // the error message, a short sentence
+      { details: "..." }, // optional additional details, can be an object, primitive, etc (any)
+    );
+  },
+}, req);
+//..
+```
+
 ## Client
 
 #### createRemote

mod.ts

@@ -2,6 +2,8 @@ export { createRemote } from "./client/remote.ts";
 
 export { respond } from "./server/response.ts";
 
+export { CustomError } from "./server/custom_error.ts";
+
 export { createRpcResponseObject } from "./server/creation.ts";
 
 export type {

server/creation.ts

@@ -6,6 +6,7 @@ import type {
 } from "../json_rpc_types.ts";
 import type { ValidationObject } from "./validation.ts";
 import type { RespondOptions, ServerMethods } from "./response.ts";
+import { CustomError } from "./custom_error.ts";
 
 export type CreationInput = {
   validationObject: ValidationObject;
@@ -27,6 +28,15 @@ async function executeMethods(
       result: await methods[obj.method](obj.params),
     };
   } catch (err) {
+    if (err instanceof CustomError) {
+      return {
+        code: err.code,
+        message: err.message,
+        id: obj.id,
+        data: err.data,
+        isError: true,
+      };
+    }
     return {
       code: -32603,
       message: "Internal error",

server/custom_error.ts

@@ -0,0 +1,12 @@
+export class CustomError extends Error {
+  name: string;
+  code: number;
+  data: any;
+
+  constructor(code: number, message: string, data?: any) {
+    super(message);
+    this.name = this.constructor.name;
+    this.code = code;
+    this.data = data;
+  }
+}

tests/respond_test.ts

@@ -8,6 +8,8 @@ import {
 
 import { respond } from "../server/response.ts";
 
+import { CustomError } from "../server/custom_error.ts";
+
 import type { ServerRequest } from "./test_deps.ts";
 
 function createReq(str: string) {
@@ -34,6 +36,11 @@ const methods = {
   throwError: () => {
     throw new Error("my error");
   },
+  throwCustomError: () => {
+    throw new CustomError(-32000, "my custom error", {
+      "details": "error details",
+    });
+  },
 };
 
 Deno.test("rpc call with positional parameters", async function (): Promise<
@@ -233,3 +240,17 @@ Deno.test("set publicErrorStack to true", async function (): Promise<void> {
     "string",
   );
 });
+
+Deno.test("rpc call with a custom error", async function (): Promise<
+  void
+> {
+  const sentToServer =
+    '{"jsonrpc": "2.0", "method": "throwCustomError", "params": [], "id": 1}';
+  const sentToClient =
+    '{"jsonrpc":"2.0","error":{"code":-32000,"message":"my custom error","data":{"details":"error details"}},"id":1}';
+
+  assertEquals(
+    await respond(methods, createReq(sentToServer)),
+    removeWhiteSpace(sentToClient),
+  );
+});