Relations Foreign Key Reference

Using the following model:

model User {
  id        String    @default(cuid()) @id @unique
  createdAt DateTime  @default(now())
  updatedAt DateTime  @updatedAt
  email     String    @unique
  name      String?
  slack     Provider? @relation(onDelete: CASCADE)
}

model Provider {
  id           String  @default(cuid()) @id @unique
  userId       String  @unique
  accessToken  String  @unique
  refreshToken String? @unique
  user         User?   @relation(onDelete: CASCADE)
}

Reading the docs… “For 1:1 relationships, it doesn't matter on which side you store the foreign key. Prisma has a convention that the foreign key is added to the model which appears first alphanumerically in your data model”.

But running SELECT * FROM sqlite_master; shows me differently

CREATE TABLE "Provider"("id" TEXT NOT NULL  ,"userId" TEXT NOT NULL DEFAULT '' ,"accessToken" TEXT NOT NULL DEFAULT '' ,"refreshToken" TEXT   ,PRIMARY KEY ("id"))

CREATE TABLE "User"("id" TEXT NOT NULL  ,"createdAt" DATE NOT NULL  ,"updatedAt" DATE NOT NULL DEFAULT '1970-01-01 00:00:00' ,"email" TEXT NOT NULL DEFAULT '' ,"name" TEXT   ,"slack" TEXT NOT NULL  REFERENCES Provider(id),PRIMARY KEY ("id"))

[mavilein]

This is fixed. It will ship with preview4.

[lecoqjacob]

After some testing, it seems the foreign key is determined by which referenced field on the two referencing models comes with lexicographical precedence.

Example 1 - userRef > userReff Model

model User2 {
  id      String @default(cuid()) @id @unique
  userRef User3
}

model User3 {
  id      String @default(cuid()) @id @unique
  userReff User2
}

Creates

CREATE TABLE "file:dev"."User2"("id" TEXT NOT NULL  ,"userRef" TEXT NOT NULL  REFERENCES User3(id),PRIMARY KEY ("id"));

CREATE TABLE "file:dev"."User3"("id" TEXT NOT NULL  ,PRIMARY KEY ("id"));

Example 2 - userRef < userRe Model

model User2 {
  id      String @default(cuid()) @id @unique
  userRef User3
}

model User3 {
  id      String @default(cuid()) @id @unique
  userRe User2
}

Creates

CREATE TABLE "file:dev"."User2"("id" TEXT NOT NULL  ,PRIMARY KEY ("id"));

CREATE TABLE "file:dev"."User3"("id" TEXT NOT NULL  ,"userRe" TEXT NOT NULL  REFERENCES User2(id),PRIMARY KEY ("id"));