Prisma单表自关联实现评论回复报错排查与解决

问题场景 #

开发基础聊天系统的评论回复功能，尝试通过Prisma单表自关联实现评论树结构，创建无父级的根评论正常，但创建回复时传入parent参数触发报错。

定义的shoutMessage模型 #

model shoutMessage {
  id        String          @id @default(cuid())
  createdAt DateTime        @default(now())
  message   String
  authorId  String
  type      Int
  parent    String?
  like      Int             @default(0)
  author    User            @relation(fields: [authorId], references: [id], onDelete: Cascade)
  likes     tb_pbot_shout[]
  root      shoutMessage?   @relation("replied", fields: [parent], references: [id], onDelete: Cascade)
  replies   shoutMessage[]  @relation("replied")
}

错误详情 #

创建回复时传入parent参数，触发如下错误：

Invalid `prisma.shoutMessage.create()` invocation:

{
  data: {
    author: {
      connect: {
        id: "cltna90na0002r4wz7dktapnp"
      }
    },
    message: "<p>asdasdasdasdasd</p>",
    parent: "cltw3r6uy0001md3c0lrnfbla",
    ~~~~~~
    type: 1,
?   id?: String,
?   createdAt?: DateTime,
?   like?: Int,
?   likes?: tb_pbot_shoutCreateNestedManyWithoutShoutInput,
?   root?: shoutMessageCreateNestedOneWithoutReplyInput,
?   reply?: shoutMessageCreateNestedManyWithoutRootInput
  }
}

Unknown argument `parent`. Available options are marked with ?.
    at async replyShout (./app/chat2/_lib/process.tsx:272:22)
    at async $$ACTION_2 (./app/chat2/page.tsx:173:5)
digest: "1873872561"

原因分析 #

parent是Prisma关联关系对应的底层数据库字段，Prisma不允许直接在CRUD操作中传入这类字段，必须通过定义的关联字段（此处为root）来完成关联操作，Prisma会自动处理parent字段的赋值。

解决方法 #

创建回复时，通过root字段的connect方法关联父评论ID，正确代码如下：

let newComment = await prisma.shoutMessage.create({
  data: {
    author: { connect: { id: user?.id } },
    message: message,
    root: { connect: { id: messageId } },
    type: type,
  },
});

评论树查询示例 #

查询时可直接通过replies字段获取子评论，实现评论树结构：

const shouts = prisma.shoutMessage.findMany({
  select: {
    id: true,
    message: true,
    author: { select: { id: true, name: true } },
    replies: {
      select: {
        id: true,
        message: true,
        author: { select: { id: true, name: true } }
      }
    }
  }
});

内容的提问来源于stack exchange，提问作者Radium Chris