如何在 Prisma 中查询/更新自关系？

Question

我有一些直接取自 Prisma 示例之一的自我关系表。

model User {
  id         Int       @id @default(autoincrement())
  name       String?
  followedBy Follows[] @relation("follower")
  following  Follows[] @relation("following")
}

model Follows {
  follower    User @relation("follower", fields: [followerId], references: [id])
  followerId  Int
  following   User @relation("following", fields: [followingId], references: [id])
  followingId Int

  @@id([followerId, followingId])
}

我想知道确定用户是否正在关注另一个用户的最佳/最惯用的方法，以及关注和取消关注的操作。 我认为最好的方法是直接查询/更新 Follows 表，但我不确定用户 model 中的 followedBy 和 following 字段是否会自动更新。

Answer 1

考虑这个例子：

1. 创建用户：

  const createUsers = await prisma.user.createMany({
    data: [
      {
        name: 'user1',
      },
      {
        name: 'user2',
      },
      {
        name: 'user3',
      },
    ],
  });

2. 定义跟随关系

  const followUsers = await prisma.follows.createMany({
    data: [
      {
        followerId: 1,
        followingId: 2,
      },
      {
        followerId: 1,
        followingId: 3,
      },
      {
        followerId: 2,
        followingId: 3,
      },
    ],
  });

3. 要获取谁是用户 1 的关注者，可以通过用户 model 以及以下 model 来实现，如下所述：

  const findFollowersThroughUser = await prisma.socialUser.findMany({
    where: {
      following: {
        some: {
          followerId: 1,
        },
      },
    },
  });

  console.log('findFollowersThroughUser', findFollowersThroughUser);

  const findFollowersThroughFollow = await prisma.follows.findMany({
    where: {
      followerId: 1,
    },
    include: {
      following: true,
    },
  });

  console.log('findFollowersThroughFollow', findFollowersThroughFollow);

这是 output：

findFollowersThroughUser [ { id: 2, name: 'user2' }, { id: 3, name: 'user3' } ]

findFollowersThroughFollow [
  {
    followerId: 1,
    followingId: 2,
    following: { id: 2, name: 'user2' }
  },
  {
    followerId: 1,
    followingId: 3,
    following: { id: 3, name: 'user3' }
  }
]

为了在有人取消关注时更新关系，在这种情况下需要从follows表中显式删除记录。