prisma2 on delete cascade...

[kdhyo]

https://www.prisma.io/docs/guides/database-workflows/cascading-deletes/mysql
https://www.prisma.io/docs/getting-started/setup-prisma/start-from-scratch-sql-node-mysql

I looked at the site above and referenced it.
but, "The change you are trying to make would violate the required relation 'PostToUser' between the Post and User models."
I want to delete All the referenced record and the referenced record..

[ryands17]

Could you share the SQL that you created and your schema.prisma after introspecting?

[kdhyo]

I tried two methods but it failed.
Please understand that you are using a translator because you are not good at English..

[ryands17]

@kdhyo

1. Create the following tables in MySQL

create table `User` (
  `id` int auto_increment primary key,
  `name` varchar(256)
);

create table `Post` (
  `id` int auto_increment primary key,
  `title` varchar(256),
  `author_id` int,
  constraint `author_fk` foreign key (`author`) references `User`(`id`) on delete cascade
);

create table `Profile` (
  `id` int auto_increment primary key,
  `userId` int unique,
  constraint `profile_fk` foreign key (`userId`) references `User`(`id`) on delete cascade
);

2. Run the following command from the command line in your project

prisma introspect --experimental-reintrospection

3. Now your schema.prisma should look like this

model Post {
  id        Int     @default(autoincrement()) @id
  title     String?
  author_id Int?
  User      User?   @relation(fields: [author_id], references: [id])

  @@index([author_id], name: "author_fk")
}

model Profile {
  id     Int   @default(autoincrement()) @id
  userId Int?  @unique
  User   User? @relation(fields: [userId], references: [id])
}

model User {
  id      Int      @default(autoincrement()) @id
  name    String?
  Post    Post[]
  Profile Profile?
}

Now if you perform a cascade delete, it will work fine.

For e.g.

const user = await prisma.user.create({
    data: {
      name: 'user 1',
      Post: {
        create: [{ title: 'post 1' }, { title: 'post 2' }],
      },
    },
  })

  await prisma.user.delete({
    where: { id: user.id },
  })

[kdhyo]

It was solved thanks to you!!!
.
If not excuse me I have a question.

• At the time of design, is it deleted due to 'on delete cascade'?
• What is the'?' after schema.prisma?

[ryands17]

Yes it is at the time of design.
The ? means that the field is optional. And this was missing in your code and which was causing the error for cascade deletes. This ? is required for the moment as there is an issue here #2057 that describes the same.

The ? will not be required after the above issue is fixed.

You can read more about data modelling in Prisma here

[kdhyo]

thank you so much!!
prisma team the best!
We will continue to use Prisma and contribute to our development!