Add support for Relationship/Referential Actions

[marcjulian]

Prisma supports Referential Actions (in Preview) with release 2.26.0. Add those referential actions to the DBML output.

DMMF type

• Field.relationOnDelete included
• Field.relationOnUpdate not supported #21

[marcjulian]

Referential action defaults are not available via the DMMF type during the generator step.

For example take the following Prisma Schema with a Mandatory relation between User and Post.

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

model User {
  id    Int         @id @default(autoincrement())
  posts Post[]
}

The referential action is not explicitly definied in the schema and results in the default Restrict, the generated migration correctly sets ON DELETE RESTRICT for this relation ship.

During the generator step Field.relationOnDelete is undefined, but expected to be Restrict.

Same happens for an Optional relation

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

model User {
  id    Int         @id @default(autoincrement())
  posts Post[]
}

The referential default is SetNull, correctly applied in the migration.

During the generator step Field.relationOnDelete is undefined, but expected to be SetNull.

---

If the default are set explicitly in the schema those values are than also available during the generator step.

model Post {
  id        Int     @id @default(autoincrement())
  title     String
  author    User    @relation(fields: [authorId], references: [id], onDelete: Restrict)
  authorId  Int
}

model User {
  id    Int         @id @default(autoincrement())
  posts Post[]
}

During the generator step Field.relationOnDelete is Restrict, but expected to be Restrict.

model Post {
  id        Int     @id @default(autoincrement())
  title     String
  author?    User    @relation(fields: [authorId], references: [id], onDelete: SetNull)
  authorId?  Int
}

model User {
  id    Int         @id @default(autoincrement())
  posts Post[]
}

During the generator step Field.relationOnDelete is SetNull, but expected to be SetNull.

[marcjulian]

Referential defaults for onDelete are correct with prisma@3.0.2