使用 JavaScript 和 Prisma ORM 查询现有的 PostgreSQL 数据库
使用 Prisma 客户端编写你的第一个查询
¥Write your first query with Prisma Client
现在你已经生成了 Prisma 客户端，你可以开始编写查询以在数据库中读取和写入数据。
¥Now that you have generated Prisma Client, you can start writing queries to read and write data in your database.
如果你正在构建 REST API，则可以在路由处理程序中使用 Prisma Client 根据传入的 HTTP 请求在数据库中读取和写入数据。如果你正在构建 GraphQL API，则可以在解析器中使用 Prisma Client 根据传入查询和突变在数据库中读取和写入数据。
¥If you're building a REST API, you can use Prisma Client in your route handlers to read and write data in the database based on incoming HTTP requests. If you're building a GraphQL API, you can use Prisma Client in your resolvers to read and write data in the database based on incoming queries and mutations.
然而，就本指南而言，你只需创建一个简单的 Node.js 脚本来了解如何使用 Prisma Client 将查询发送到数据库。一旦你了解了 API 的工作原理，你就可以开始将其集成到实际的应用代码中（例如 REST 路由处理程序或 GraphQL 解析器）。
¥For the purpose of this guide however, you'll just create a plain Node.js script to learn how to send queries to your database using Prisma Client. Once you have an understanding of how the API works, you can start integrating it into your actual application code (e.g. REST route handlers or GraphQL resolvers).
创建一个名为 index.js 的新文件并添加以下代码：
¥Create a new file named index.js and add the following code to it:
const { PrismaClient } = require('@prisma/client')
const prisma = new PrismaClient()
async function main() {
// ... you will write your Prisma Client queries here
}
main()
.then(async () => {
await prisma.$disconnect()
})
.catch(async (e) => {
console.error(e)
await prisma.$disconnect()
process.exit(1)
})
async function main() {
const allUsers = await prisma.user.findMany()
console.log(allUsers)
}
现在使用以下命令运行代码：
¥Now run the code with this command:
node index.js
如果你使用数据库自省步骤中的架构创建了数据库，则查询应打印一个空数组，因为数据库中尚无 User 记录。
¥If you created a database using the schema from the database introspection step, the query should print an empty array because there are no User records in the database yet.
[]
如果你内省了包含记录的现有数据库，则查询应返回 JavaScript 对象数组。
¥If you introspected an existing database with records, the query should return an array of JavaScript objects.
将数据写入数据库
¥Write data into the database
你在上一节中使用的 findMany 查询仅从数据库中读取数据。在本节中，你将学习如何编写查询以将新记录写入 Post 和 User 表中。
¥The findMany query you used in the previous section only reads data from the database. In this section, you'll learn how to write a query to write new records into the Post and User tables.
调整 main 函数以向数据库发送 create 查询：
¥Adjust the main function to send a create query to the database:
async function main() {
await prisma.user.create({
data: {
name: 'Alice',
email: 'alice@prisma.io',
posts: {
create: { title: 'Hello World' },
},
profile: {
create: { bio: 'I like turtles' },
},
},
})
const allUsers = await prisma.user.findMany({
include: {
posts: true,
profile: true,
},
})
console.dir(allUsers, { depth: null })
}
此代码使用 嵌套写入 查询创建新的 User 记录以及新的 Post 和 Profile 记录。User 记录分别通过 Post.author ↔ User.posts 和 Profile.user ↔ User.profile 关系字段 连接到另外两个记录。
¥This code creates a new User record together with new Post and Profile records using a nested write query. The User record is connected to the two other ones via the Post.author ↔ User.posts and Profile.user ↔ User.profile relation fields respectively.
请注意，你将 include 选项传递给 findMany，这告诉 Prisma 客户端在返回的 User 对象上包含 posts 和 profile 关系。
¥Notice that you're passing the include option to findMany which tells Prisma Client to include the posts and profile relations on the returned User objects.
使用以下命令运行代码：
¥Run the code with this command:
node index.js
在继续下一部分之前，你需要对刚刚使用 update 查询创建的 Post 记录进行 "publish" 操作。调整 main 功能如下：
¥Before moving on to the next section, you'll "publish" the Post record you just created using an update query. Adjust the main function as follows:
async function main() {
const post = await prisma.post.update({
where: { id: 1 },
data: { published: true },
})
console.log(post)
}
现在使用与之前相同的命令运行代码：
¥Now run the code using the same command as before:
node index.js