how to do Prisma soft delete with NestJS?

Question

I had tried to implement this method in my application. but I don't have depth knowledge of Prisma. Kindly explain that with some examples.

Answer 1

You can write a middleware to mark a question as a deleted instead of actually deleting it.

schema.prisma

datasource db {
  provider = "postgresql"
  url      = env("DATABASE_URL")
}

generator client {
  provider = "prisma-client-js"
}

model Post {
  id      Int     @id @default(autoincrement())
  title   String
  content String?
  user    User?   @relation(fields: [userId], references: [id])
  userId  Int?
  tags    Tag[]
  views   Int     @default(0)
  deleted Boolean @default(false)
}

Here a field called deleted is added to the Post model.

Middleware performs the following operation:

• Intercepts delete and deleteMany queries for the Post model
• Changes the params.action to update and updateMany respectively
• Introduces a data argument and sets { deleted: true }, preserving other filter arguments if they exist

script.ts

import { PrismaClient } from '@prisma/client'

const prisma = new PrismaClient({})

async function main() {
  /***********************************/
  /* SOFT DELETE MIDDLEWARE */
  /***********************************/

  prisma.$use(async (params, next) => {
    // Check incoming query type
    if (params.model == 'Post') {
      if (params.action == 'delete') {
        // Delete queries
        // Change action to an update
        params.action = 'update'
        params.args['data'] = { deleted: true }
      }
      if (params.action == 'deleteMany') {
        // Delete many queries
        params.action = 'updateMany'
        if (params.args.data != undefined) {
          params.args.data['deleted'] = true
        } else {
          params.args['data'] = { deleted: true }
        }
      }
    }
    return next(params)
  })