Extract shared error code

+ Create new functions for generating errors

src/Controllers/common.ts

@@ -3,6 +3,21 @@ import { PrismaClientKnownRequestError, PrismaClientUnknownRequestError } from "
 import { Request, Response } from "express";
 import prisma from "../lib/prisma";
 
+interface StringIndexedObject {
+  [k: string]: any;
+}
+
+export function createError(message: string, payload: StringIndexedObject = {}, links: StringIndexedObject = {}) {
+  return {
+    type: "error",
+    payload: {
+      message: message,
+      ...payload,
+    },
+    _links: links,
+  };
+}
+
 export enum DataType {
   STRING = "string",
   NUMBER = "number",

src/Controllers/media.controller.ts

@@ -2,25 +2,19 @@ import { Request, Response } from "express";
 import fs from "fs";
 import isSvg from "is-svg";
 import { fromBuffer as fileTypeFromBuffer } from "file-type";
+import { AUTH_ERROR, createError, createInsufficientPermissionsError } from "./common";
+
+function createMediaLinks(fileName: string) {
+  return [{ rel: "self", type: "GET", href: `/api/media/${fileName}` }];
+}
 
 export const uploadImage = async (req: Request, res: Response) => {
   if (!req.auth?.isAuthenticated) {
-    return res.status(500).json({
-      type: "failure",
-      payload: {
-        message: "The server was not able to validate your credentials; Please try again later",
-      },
-    });
+    return res.status(500).json(AUTH_ERROR);
   }
 
   if (!(req.auth.permission_level === "ELEVATED")) {
-    return res.status(403).json({
-      type: "error",
-      payload: {
-        message: "You do not have sufficient permissions to use this feature",
-        required_level: "ELEVATED",
-      },
-    });
+    return res.status(403).json(createInsufficientPermissionsError());
   }
 
   if (!req.files || !("file" in req.files)) {
@@ -50,13 +44,7 @@ export const uploadImage = async (req: Request, res: Response) => {
 
   if (file.size > 1024 * 1024) {
     // Maybe resize (express-fileupload seems to support this)
-    return res.status(413).json({
-      type: "error",
-      payload: {
-        message: "The uploaded image is too large",
-        max_size: "1 MB",
-      },
-    });
+    return res.status(413).json(createError("The uploaded image is too large", { max_size: "1 MB" }));
   }
 
   const fileIsSvg = isSvg(file.data);
@@ -64,31 +52,19 @@ export const uploadImage = async (req: Request, res: Response) => {
 
   if (!(fileType && ["image/jpeg", "image/png"].includes(fileType.mime))) {
     if (!fileIsSvg)
-      return res.status(415).json({
-        type: "error",
-        payload: {
-          message:
-            "The uploaded image does not satisfy the MIME type constraints (Only image/jpeg, image/png and SVG files are accepted)",
-        },
-      });
+      return res
+        .status(415)
+        .json(
+          createError(
+            "The uploaded image does not satisfy the MIME type constraints (Only image/jpeg, image/png and SVG files are accepted)"
+          )
+        );
   }
 
   const fileName = file.md5 + (fileIsSvg ? ".svg" : "." + fileType?.ext);
 
   if (fs.existsSync("media/" + fileName)) {
-    return res.status(409).json({
-      type: "error",
-      payload: {
-        message: "The uploaded file already exists",
-      },
-      _links: [
-        {
-          rel: "self",
-          type: "GET",
-          href: "/api/media/" + fileName,
-        },
-      ],
-    });
+    return res.status(409).json(createError("The uploaded file already exists", {}, createMediaLinks(fileName)));
   }
 
   file.mv("media/" + fileName, console.error);
@@ -98,12 +74,6 @@ export const uploadImage = async (req: Request, res: Response) => {
     payload: {
       message: "The file was uploaded and created on the server",
     },
-    _links: [
-      {
-        rel: "self",
-        type: "GET",
-        href: "/api/media/" + fileName,
-      },
-    ],
+    _links: createMediaLinks(fileName),
   });
 };