Prisma Cascade Delete

Prisma (v2) is one of the hottest ORM's right now (you can see some of the reasion I think so here). It still has some important holes, though. Cascade delete is one of the most proeminent ones, and most of the "automatic" workarounds have some issue.

This package exposes a cascadeDelete function that uses the information available at the _prisma models_ to perform cascade deletes on one-to-many and many-to-many (with a relation table) relations. The cascade goes as deep as the relation goes (see example below).

Installation

``
npm install prisma-cascade-delete
`

Usage

`javascript
import { cascadeDelete } from "prisma-cascade-delete";

cascadeDelete(prisma, modelName, where);
// prisma is the prisma-client instance from your app
// modelName must be the same as used in the prisma schema (e.g. "User")
// where is an object accepted by prisma queries as a where statement
`

Example

`javascript
model User {
id Int @id @default(autoincrement())
email String @unique
name String?
posts Post[]
}

model Post {
id Int @id @default(autoincrement())
title String
content String?
published Boolean @default(false)
viewCount Int @default(0)
author User @relation(fields: [authorId], references: [id])
authorId Int
}

model Tag {
id Int @id @default(autoincrement())
name String
}

model TagsInPost {
id Int @id @default(autoincrement())
post Post @relation(fields: [postId], references: [id])
postId Int
tag Tag @relation(fields: [tagId], references: [id])
tagId Int

}

`

In the schema above, we would expect that if we delete a User, all its Posts and all the Tags associated to this posts would be deleted as well. However, there is no way to set this up.

That's where cascadeDelete comes in;

`javascript
import { cascadeDelete } from "prisma-cascade-delete";
import { PrismaClient } from "@prisma/client";

const prisma = new PrismaClient();

cascadeDelete(prisma, "User", { id: 1 });
`

This function will generate

`javascript
const userDelete = prisma.user.delete({ where: { id: 1 } });
const postsDelete = prisma.post.deleteMany({ where: { userId: 1 } });
const postTagDelete = prisma.tagsInPost.deleteMany({
where: { OR: [{ postId: 1 }, { postId: 2 }] },
});
// Imagining that the user posted posts 1 and 2

prisma.$transaction([postTageDelete,postsDelete,userDelete])

``