多对多关系棱镜

Posted 2023-03-30

【中文标题】多对多关系棱镜

【英文标题】：Many to many relationship prisma

【发布时间】：2022-01-19 22:24:20

【问题描述】：

我有一个带有 Typescript mysql 的快速服务器，也使用 Prisma Js 进行 ORM。这些是我的架构：

model Post 
  id          Int                 @id @default(autoincrement())
  title       String              @db.VarChar(35)
  description String              @db.VarChar(250)
  category    CategoriesOnPosts[]
  author      User                @relation(fields: [userId], references: [id])
  userId      String
  createdAt   DateTime            @default(now())
  updatedAt   DateTime            @updatedAt


model Category 
 id    Int                 @id @default(autoincrement())
 name  String              @unique @db.VarChar(18)
 about String              @db.VarChar(60)
 posts CategoriesOnPosts[]


model CategoriesOnPosts 
 post       Post     @relation(fields: [postId], references: [id])
postId     Int
category   Category @relation(fields: [categoryId], references: [id])
categoryId Int

 @@id([postId, categoryId])

首先我创建一个新类别然后我将创建一个新帖子但我无法弄清楚这个问题有人可以帮助我吗？这也是我的要求：

export const createCategory = async (req: Request, res: Response) => 
 try 
   const  name, about  = req.body;
   if (!name || !about) return res.status(400).json( error: 'Please fill all inputs!' );
   const existCategory = await prisma.category.findUnique( where:  name  );
   if (existCategory) return res.status(400).json( error: 'This category already exists!' );
   const category = await prisma.category.create(
     data: 
        name,
        about,
     ,
  );
  res.status(201).json(category);
  catch (error) 
  res.status(500).json( error: error.message );
 
;

但是当我尝试创建新帖子时，我在 CategoriesOnPosts 模型中看不到任何类别

【参考方案1】：

为了简化示例，我已从您的架构中删除了用户

datasource mysql 
  provider = "mysql"
  url      = env("DATABASE_URL")


generator client 
  provider = "prisma-client-js"


model Post 
  id          Int                 @id @default(autoincrement())
  title       String
  description String
  category    CategoriesOnPosts[]
  createdAt   DateTime            @default(now())
  updatedAt   DateTime            @updatedAt


model Category 
  id    Int                 @id @default(autoincrement())
  name  String              @unique
  about String
  posts CategoriesOnPosts[]


model CategoriesOnPosts 
  post       Post     @relation(fields: [postId], references: [id])
  postId     Int
  category   Category @relation(fields: [categoryId], references: [id])
  categoryId Int

  @@id([postId, categoryId])

执行迁移后，我执行了以下代码：

const  PrismaClient  = require('@prisma/client')
const prisma = new PrismaClient()

const loadData = async () => 
  const category = await prisma.category.create(
    data: 
      name: 'Category 1',
      about: 'Description 1',
    ,
  );

  console.log(category);

  const post = await prisma.post.create(
    data: 
      title: 'Post 1',
      description: 'Description 1',
      category: 
        create: 
          category: 
            connect: 
              id: category.id
            
          
        
      
    ,
  );

  console.log(post);
;

loadData()

一切正常，给你一张带有结果的图片

【讨论】：

我真的很感谢你！这是很好的解释

很高兴！ :)，请给我的答案打分！ :)