类型实用程序

Prisma Client 中存在多种类型实用程序，可以帮助创建高度类型安全的扩展。

¥Several type utilities exist within Prisma Client that can assist in the creation of highly type-safe extensions.

类型实用程序

¥Type Utilities

Prisma 客户端类型实用程序是你的应用和 Prisma 客户端扩展中可用的实用程序，并提供为你的扩展构建安全和可扩展类型的有用方法。

¥Prisma Client type utilities are utilities available within your application and Prisma Client extensions and provide useful ways of constructing safe and extendable types for your extension.

可用的类型实用程序有：

¥The type utilities available are:

Exact<Input, Shape>：在 Input 上强制执行严格的类型安全。Exact 确保泛型类型 Input 严格符合你在 Shape 中指定的类型。它 narrows Input 到最精确的类型。

¥Exact<Input, Shape>: Enforces strict type safety on Input. Exact makes sure that a generic type Input strictly complies with the type that you specify in Shape. It narrows Input down to the most precise types.
Args<Type, Operation>：检索任何给定模型和操作的输入参数。这对于想要执行以下操作的扩展作者特别有用：

¥Args<Type, Operation>: Retrieves the input arguments for any given model and operation. This is particularly useful for extension authors who want to do the following:
- 重用现有类型来扩展或修改它们。
  
  ¥Re-use existing types to extend or modify them.
- 受益于与现有操作相同的自动补齐体验。
  
  ¥Benefit from the same auto-completion experience as on existing operations.
Result<Type, Arguments, Operation>：获取输入参数并提供给定模型和操作的结果。你通常会将其与 Args 结合使用。与 Args 一样，Result 可帮助你重用现有类型来扩展或修改它们。

¥Result<Type, Arguments, Operation>: Takes the input arguments and provides the result for a given model and operation. You would usually use this in conjunction with Args. As with Args, Result helps you to re-use existing types to extend or modify them.
Payload<Type, Operation>：检索结果的整个结构，作为给定模型和操作的标量和关系对象。例如，你可以使用它来确定哪些键是类型级别的标量或对象。

¥Payload<Type, Operation>: Retrieves the entire structure of the result, as scalars and relations objects for a given model and operation. For example, you can use this to determine which keys are scalars or objects at a type level.

以下示例基于 findFirst 创建一个新操作 exists。它具有 findFirst. 的所有参数。

¥The following example creates a new operation, exists, based on findFirst. It has all of the arguments that findFirst.

const prisma = new PrismaClient().$extends({
  model: {
    $allModels: {
      // Define a new `exists` operation on all models
      // T is a generic type that corresponds to the current model
      async exists<T>(
        // `this` refers to the current type, e.g. `prisma.user` at runtime
        this: T,

        // The `exists` function will use the `where` arguments from the current model, `T`, and the `findFirst` operation
        where: Prisma.Args<T, 'findFirst'>['where']
      ): Promise<boolean> {
        // Retrieve the current model at runtime
        const context = Prisma.getExtensionContext(this)

        // Prisma Client query that retrieves data based
        const result = await (context as any).findFirst({ where })
        return result !== null
      },
    },
  },
})

async function main() {
  const user = await prisma.user.exists({ name: 'Alice' })
  const post = await prisma.post.exists({
    OR: [
      { title: { contains: 'Prisma' } },
      { content: { contains: 'Prisma' } },
    ],
  })
}

向方法添加自定义属性

¥Add a custom property to a method

以下示例说明了如何将自定义参数添加到扩展中的方法：

¥The following example illustrates how you can add custom arguments, to a method in an extension:

type CacheStrategy = {
  swr: number
  ttl: number
}

const prisma = new PrismaClient().$extends({
  model: {
    $allModels: {
      findMany<T, A>(
        this: T,
        args: Prisma.Exact<
          A,
          // For the `findMany` method, use the arguments from model `T` and the `findMany` method
          // and intersect it with `CacheStrategy` as part of `findMany` arguments
          Prisma.Args<T, 'findMany'> & CacheStrategy
        >
      ): Prisma.Result<T, A, 'findMany'> {
        // method implementation with the cache strategy
      },
    },
  },
})

async function main() {
  await prisma.post.findMany({
    cacheStrategy: {
      ttl: 360,
      swr: 60,
    },
  })
}

这里的例子只是概念性的。为了使实际的缓存发挥作用，你必须实现逻辑。如果你对缓存扩展/服务感兴趣，我们建议你查看 Prisma 加速。

¥The example here is only conceptual. For the actual caching to work, you will have to implement the logic. If you're interested in a caching extension/ service, we recommend taking a look at Prisma Accelerate.

类型 实用程序​

向方法添加自定义属性​

类型实用程序

向方法添加自定义属性