this turned out to be pretty clean tbh

package.json

@@ -3,7 +3,7 @@
   "version": "0.1.0",
   "private": true,
   "scripts": {
-    "dev": "dotenv -e .env.local prisma db push && dotenv -e .env.local prisma generate && dotenv -e .env.local next dev",
+    "dev": "dotenv -e .env.local prisma db push && dotenv -e .env.local prisma generate && NODE_OPTIONS=--inspect dotenv -e .env.local next dev",
     "build": "next build",
     "start": "next start",
     "lint": "next lint",

pages/api/events/[slug].ts

@@ -1,17 +1,23 @@
 import { client } from "../../../utils/prismaClient";
 import { NextApiRequest, NextApiResponse } from "next";
 import { ApiResult } from "../../../types/api";
-import { restInPeace } from "../../../utils/restInPeace";
+import { Model, restInPeace } from "../../../utils/restInPeace";
 import { default as cryptoRandomString} from "crypto-random-string";
-import { handleInterrupts } from "../../../utils/interrupt";
+import { handleInterrupts, Interrupt } from "../../../utils/interrupt";
 import { authorizeUser } from "../../../utils/apiAuth";
-import { User } from "@prisma/client";
+import { Event } from "@prisma/client";
 
 
 export default async function handler(req: NextApiRequest, res: NextApiResponse<ApiResult<Event | Event[]>>) {
     handleInterrupts(res, async () => {
         const user = await authorizeUser(req, res)
 
+        const canEdit = async (model: Model, obj?: Event) => {
+            if(obj && obj.creatorId !== user.id) {
+                throw new Interrupt(403, {error: "Only the creator can edit an event"})
+            }
+        }
+
         const which = {
             slug: req.query.slug
         }
@@ -28,7 +34,9 @@ export default async function handler(req: NextApiRequest, res: NextApiResponse<
             model: client.event,
             retrieve: {which},
             create: {create},
-            // TODO: this might prove problematic
+            upsert: {create, update, before: canEdit},
+            update: {update, before: canEdit},
+            destroy: {before: canEdit},
         })
     })
 }

utils/restInPeace.ts

@@ -3,7 +3,7 @@ import { ApiError, ApiResult } from "../types/api";
 
 
 // I don't know what the typing of a Prisma model is.
-type Model = any
+export type Model = any
 
 
 type RestInPeaceOptions<T> = {
@@ -97,7 +97,7 @@ export async function restInPeace<T>(req: NextApiRequest, res: NextApiResponse<A
 
 
 interface OperationOptions<T> {
-    before?: (model: T) => Promise<void>,
+    before?: (model: T, obj?: any) => Promise<void>,
     after?: (model: T, obj?: any) => Promise<any>,
 }
 
@@ -106,6 +106,7 @@ interface OperationOptions<T> {
 
 
 interface HeadOptions<T> extends OperationOptions<T> {
+    before?: (model: T) => Promise<void>,
     after?: (model: T) => Promise<void>,
 }
 
@@ -123,6 +124,7 @@ async function handleHead<T>(res: NextApiResponse<"">, model: Model, options: He
 
 
 interface OptionsOptions<T> extends OperationOptions<T> {
+    before?: (model: T) => Promise<void>,
     after?: (model: T) => Promise<void>,
 }
 
@@ -145,6 +147,7 @@ interface ListOptions<T> extends OperationOptions<T> {
      */
     where?: object,
 
+    before?: (model: T) => Promise<void>,
     after?: (model: T, obj: T[]) => Promise<T[]>,
 }
 
@@ -170,6 +173,7 @@ interface RetrieveOptions<T> extends OperationOptions<T> {
      */
     which?: object,
 
+    before?: (model: T) => Promise<void>,
     after?: (model: T, obj: T) => Promise<T>,
 }
 
@@ -196,6 +200,7 @@ interface CreateOptions<T> extends OperationOptions<T> {
      */
     create: object,
 
+    before?: (model: T) => Promise<void>,
     after?: (model: T, obj: T) => Promise<T>,
 }
 
@@ -231,6 +236,7 @@ interface UpsertOptions<T> extends OperationOptions<T> {
      */
     update: object,
 
+    before?: (model: T, obj?: T) => Promise<void>,
     after?: (model: T, obj: T) => Promise<T>,
 }
 
@@ -238,7 +244,8 @@ interface UpsertOptions<T> extends OperationOptions<T> {
  * Handle a `PUT` HTTP request where a single item is either created or updated.
  */
 async function handleUpsert<T>(res: NextApiResponse<ApiResult<T>>, model: Model, options: UpsertOptions<T>) {
-    await options.before?.(model)
+    const initialObj = await model.findUnique({ where: options.which })
+    await options.before?.(model, initialObj)
     const obj = await model.upsert({
         where: options.which,
         create: options.create,
@@ -265,6 +272,7 @@ interface UpdateOptions<T> extends OperationOptions<T> {
      */
     update: object,
 
+    before?: (model: T, obj?: T) => Promise<void>,
     after?: (model: T, obj: T) => Promise<T>,
 }
 
@@ -272,7 +280,8 @@ interface UpdateOptions<T> extends OperationOptions<T> {
  * Handle a `PATCH` HTTP request where a single item is updated.
  */
 async function handleUpdate<T>(res: NextApiResponse<ApiResult<T>>, model: Model, options: UpdateOptions<T>) {
-    await options.before?.(model)
+    const initialObj = await model.findUnique({ where: options.which })
+    await options.before?.(model, initialObj)
     const obj = await model.update({
         where: options.which,
         data: options.update,
@@ -293,6 +302,7 @@ interface DestroyOptions<T> extends OperationOptions<T> {
      */
     which?: object,
 
+    before?: (model: T, obj?: T) => Promise<void>,
     after?: (model: T) => Promise<void>,
 }
 
@@ -300,7 +310,8 @@ interface DestroyOptions<T> extends OperationOptions<T> {
  * Handle a `DELETE` HTTP request where a single item is destroyed.
  */
 async function handleDestroy<T>(res: NextApiResponse<ApiResult<T>>, model: Model, options: DestroyOptions<T>) {
-    await options.before?.(model)
+    const initialObj = await model.findUnique({ where: options.which })
+    await options.before?.(model, initialObj)
     await model.delete({
         where: options.which,
     })