意见

数据库视图允许你命名和存储查询。在关系数据库中，视图是存储的 SQL 查询，可能包含多个表中的列或计算值（例如聚合）。在 MongoDB 中，视图是可查询的对象，其中内容由其他集合上的聚合管道定义。

¥Database views allow you to name and store queries. In relational databases, views are stored SQL queries that might include columns in multiple tables, or calculated values such as aggregates. In MongoDB, views are queryable objects where the contents are defined by an aggregation pipeline on other collections.

views 预览功能允许你使用 view 关键字表示 Prisma 架构中的视图。要在 Prisma ORM 中使用视图，请按照以下步骤操作：

¥The views preview feature allows you to represent views in your Prisma schema with the view keyword. To use views in Prisma ORM, follow these steps:

启用 views 预览功能

¥Enable the views preview feature
在底层数据库中创建视图，直接或作为手动添加到 Prisma Migrate 迁移文件，或使用现有视图

¥Create a view in the underlying database, either directly or as a manual addition to a Prisma Migrate migration file, or use an existing view
表示 Prisma 架构中的视图

¥Represent the view in your Prisma schema
在 Prisma 客户端中查询视图

¥Query the view in Prisma Client

警告

目前，视图支持是预览的一项功能。你可以使用 view 关键字将视图添加到 Prisma 架构中，或使用 db pull 内省数据库架构中的视图。你尚无法使用 Prisma Migrate 和 db push 将架构中的视图应用到数据库，除非使用 --create-only 标志将更改手动添加到迁移文件中。

有关此功能的最新进展，请关注我们的 GitHub 问题。

¥Support for views is currently a Preview feature. You can add a view to your Prisma schema with the view keyword or introspect the views in your database schema with db pull. You cannot yet apply views in your schema to your database with Prisma Migrate and db push unless the changes are added manually to your migration file using the --create-only flag.

For updates on progress with this feature, follow our GitHub issue.

启用 `views` 预览功能

¥Enable the views preview feature

对视图的支持目前处于早期预览阶段。要启用 views 预览功能，请将 views 功能标志添加到 Prisma Schema 中 generator 块的 previewFeatures 字段：

¥Support for views is currently in an early preview. To enable the views preview feature, add the views feature flag to the previewFeatures field of the generator block in your Prisma Schema:

schema.prisma

generator client {
  provider        = "prisma-client"
  previewFeatures = ["views"]
}

Please leave feedback about this preview feature in our dedicated preview feature feedback issue for views.

在底层数据库中创建视图

¥Create a view in the underlying database

Currently, you cannot apply views that you define in your Prisma schema to your database with Prisma Migrate or db push.相反，你必须首先在基础数据库中创建视图（手动或作为迁移的一部分）。

¥Currently, you cannot apply views that you define in your Prisma schema to your database with Prisma Migrate or db push. Instead, you must first create the view in the underlying database, either manually or as part of a migration.

例如，采用以下包含 User 模型和相关 Profile 模型的 Prisma 架构：

¥For example, take the following Prisma schema with a User model and a related Profile model:

Relational databases
MongoDB

model User {
  id      Int      @id @default(autoincrement())
  email   String   @unique
  name    String?
  profile Profile?
}

model Profile {
  id     Int    @id @default(autoincrement())
  bio    String
  user   User   @relation(fields: [userId], references: [id])
  userId Int    @unique
}

model User {
  id      String   @id @default(auto()) @map("_id") @db.ObjectId
  email   String   @unique
  name    String?
  profile Profile?
}

model Profile {
  id     String @id @default(auto()) @map("_id") @db.ObjectId
  bio    String
  User   User   @relation(fields: [userId], references: [id])
  userId String @unique @db.ObjectId
}

接下来，在底层数据库中获取 UserInfo 视图，该视图组合了 User 模型中的 email 和 name 字段以及 Profile 模型中的 bio 字段。

¥Next, take a UserInfo view in the underlying database that combines the email and name fields from the User model and the bio field from the Profile model.

对于关系数据库，创建该视图的 SQL 语句是：

¥For a relational database, the SQL statement to create this view is:

CREATE VIEW "UserInfo" AS
    SELECT u.id, email, name, bio
    FROM "User" u
    LEFT JOIN "Profile" p ON u.id = p."userId";

对于 MongoDB，你可以使用以下命令进行创建一个视图：

¥For MongoDB, you can create a view with the following command:

db.createView('UserInfo', 'User', [
  {
    $lookup: {
      from: 'Profile',
      localField: '_id',
      foreignField: 'userId',
      as: 'ProfileData',
    },
  },
  {
    $project: {
      _id: 1,
      email: 1,
      name: 1,
      bio: '$ProfileData.bio',
    },
  },
  { $unwind: '$bio' },
])

将视图与 Prisma Migrate 和 `db push` 结合使用

¥Use views with Prisma Migrate and db push

如果你使用 Prisma Migrate 或 db push 将更改应用到 Prisma 架构，Prisma ORM 不会创建或运行任何与视图相关的 SQL。

¥If you apply changes to your Prisma schema with Prisma Migrate or db push, Prisma ORM does not create or run any SQL related to views.

要在迁移中包含视图，请运行 migrate dev --create-only，然后手动将视图的 SQL 添加到迁移文件中。或者，你可以在数据库中手动创建视图。

¥To include views in a migration, run migrate dev --create-only and then manually add the SQL for views to your migration file. Alternatively, you can create views manually in the database.

将视图添加到你的 Prisma 架构

¥Add views to your Prisma schema

要将视图添加到 Prisma 模式，请使用 view 关键字。

¥To add a view to your Prisma schema, use the view keyword.

你可以在 Prisma 模式中表示上面示例中的 UserInfo 视图，如下所示：

¥You can represent the UserInfo view from the example above in your Prisma schema as follows:

Relational databases
MongoDB

view UserInfo {
  id    Int
  email String
  name  String
  bio   String
}

view UserInfo {
  id    String @map("_id") @db.ObjectId
  email String
  name  String
  bio   String
}

手写

¥Write by hand

view 块由两个主要部分组成：

¥A view block is comprised of two main pieces:

view 块定义

¥The view block definition
视图的字段定义

¥The view's field definitions

这两部分允许你定义生成的 Prisma 客户端中的视图名称以及视图查询结果中显示的列。

¥These two pieces allow you to define the name of your view in the generated Prisma Client and the columns present in your view's query results.

定义 `view` 块

¥Define a view block

要定义上面示例中的 UserInfo 视图，首先使用 view 关键字在你的架构中定义一个名为 UserInfo 的 view 块：

¥To define the UserInfo view from the example above, begin by using the view keyword to define a view block in your schema named UserInfo:

view UserInfo {
  // Fields
}

定义字段

¥Define fields

视图的属性称为字段，其中包括：

¥The properties of a view are called fields, which consist of:

字段名称

¥A field name
字段类型

¥A field type

UserInfo 示例视图的字段可以定义如下：

¥The fields of the UserInfo example view can be defined as follows:

Relational databases
MongoDB

view UserInfo {
  id    Int
  email String
  name  String
  bio   String
}

view UserInfo {
  id    String @map("_id") @db.ObjectId
  email String
  name  String
  bio   String
}

view 块的每个字段代表底层数据库中视图的查询结果中的一列。

¥Each field of a view block represents a column in the query results of the view in the underlying database.

使用内省

¥Use introspection

警告

Currently views can only be introspected with PostgreSQL, MySQL, SQL Server and CockroachDB databases.如果你使用其他数据库提供商，则必须手动添加你的视图。

¥Currently views can only be introspected with PostgreSQL, MySQL, SQL Server and CockroachDB databases. If you are using another database provider, your views must be added manually.

如果你的数据库中定义了一个或多个现有视图，introspection 将在你的 Prisma 架构中自动生成代表这些视图的 view 块。

¥If you have an existing view or views defined in your database, introspection will automatically generate view blocks in your Prisma schema that represent those views.

假设示例 UserInfo 视图存在于你的底层数据库中，运行以下命令将在你的 Prisma 架构中生成代表该视图的 view 块：

¥Assuming the example UserInfo view exists in your underlying database, running the following command will generate a view block in your Prisma schema representing that view:

npx prisma db pull

生成的 view 块将定义如下：

¥The resulting view block will be defined as follows:

view UserInfo {
  id    Int?
  email String?
  name  String?
  bio   String?
}

警告

请注意，目前 db pull 仅在使用 PostgreSQL、MySQL、SQL Server 或 CockroachDB 时内省模式中的视图。对此工作流程的支持将扩展到其他数据库提供商。

¥Please note for now db pull will only introspect views in your schema when using PostgreSQL, MySQL, SQL Server or CockroachDB. Support for this workflow will be extended to other database providers.

`views` 目录

¥The views directory

使用一个或多个现有视图对数据库进行内省还将在 prisma 目录中创建一个新的 views 目录（从 Prisma 版本 4.12.0 开始）。该目录将包含一个以数据库架构命名的子目录，其中包含该架构中内省的每个视图的 .sql 文件。每个文件都将以单个视图命名，并将包含相关视图定义的查询。

¥Introspection of a database with one or more existing views will also create a new views directory within your prisma directory (starting with Prisma version 4.12.0). This directory will contain a subdirectory named after your database's schema which contains a .sql file for each view that was introspected in that schema. Each file will be named after an individual view and will contain the query the related view defines.

例如，使用上面使用的模型对具有默认 public 模式的数据库进行内省后，你会发现创建了一个包含以下内容的 prisma/views/public/UserInfo.sql 文件：

¥For example, after introspecting a database with the default public schema using the model used above you will find a prisma/views/public/UserInfo.sql file was created with the following contents:

SELECT
  u.id,
  u.email,
  u.name,
  p.bio
FROM
  (
    "User" u
    LEFT JOIN "Profile" p ON ((u.id = p."userId"))
  );

Prisma 客户端中的查询视图

¥Query views in Prisma Client

注意

Be sure to run prisma generate after updating your Prisma schema so that the view definitions become part of your Prisma Client API.

你可以像查询模型一样在 Prisma Client 中查询视图。例如，以下查询在上面定义的 UserInfo 视图中查找 name 为 'Alice' 的所有用户。

¥You can query views in Prisma Client in the same way that you query models. For example, the following query finds all users with a name of 'Alice' in the UserInfo view defined above.

const userinfo = await prisma.userInfo.findMany({
  where: {
    name: 'Alice',
  },
})

注意

Write-queries (create/update/delete) are not supported on views.

特殊类型的视图

¥Special types of views

本节介绍如何将 Prisma ORM 与数据库中的可更新视图和物化视图结合使用。

¥This section describes how to use Prisma ORM with updatable and materialized views in your database.

可更新的视图

¥Updatable views

某些数据库支持可更新视图（例如 PostgreSQL、MySQL 和 SQL Server）。可更新视图允许创建、更新或删除条目（如果底层数据库支持此类操作）。

¥Some databases support updatable views (e.g. PostgreSQL, MySQL, and SQL Server). Updatable views allow creating, updating, or deleting entries if the underlying database supports such operations.

无论数据库的功能如何，Prisma ORM 都不允许对视图进行任何修改（创建、更新、删除）。此更改提供了防护机制，以确保视图在 Prisma 客户端中始终被视为只读实体。因此，Prisma 客户端 API 中不会为 view 块生成执行写入操作的方法，例如 create、update、delete 或 upsert。

¥Prisma ORM does not allow any mutations (create, update, delete) on views, regardless of the database's capabilities. This change provides guardrails to ensure that views are treated consistently as read-only entities within Prisma Client. As a result, methods to perform writes such as create, update, delete, or upsert are not generated for view blocks in your Prisma Client API.

如果你需要修改视图表示的数据，则必须直接在底层表上执行写入操作或使用原始 SQL 查询。

¥If you need to modify data represented by a view, you must perform the write operations directly on the underlying tables or use raw SQL queries.

物化视图

¥Materialized views

一些数据库支持物化视图，例如 PostgreSQL、CockroachDB、MongoDB 和 SQL Server（此处称为 "索引视图"）。

¥Some databases support materialized views, e.g. PostgreSQL, CockroachDB, MongoDB, and SQL Server (where they're called "indexed views").

物化视图保留视图查询的结果以实现更快的访问，并且仅根据需要进行更新。

¥Materialized views persist the result of the view query for faster access and only update it on demand.

目前，Prisma ORM 不支持物化视图。但是，当你使用手动创建视图时，你还可以使用底层数据库中的相应命令创建物化视图。然后，你可以使用 Prisma Client 的 TypedSQL 功能执行命令并手动刷新视图。

¥Currently, Prisma ORM does not support materialized views. However, when you manually create a view, you can also create a materialized view with the corresponding command in the underlying database. You can then use Prisma Client's TypedSQL functionality to execute the command and refresh the view manually.

将来，Prisma 客户端可能支持将单个视图标记为物化，并添加 Prisma 客户端方法来刷新物化视图。请根据你的用例对我们的 views 反馈问题发表评论。

¥In the future Prisma Client might support marking individual views as materialized and add a Prisma Client method to refresh the materialized view. Please comment on our views feedback issue with your use case.

局限性

¥Limitations

Prisma ORM 将所有 view 块视为数据库查询的只读表示，而非真正的表。Because of this, several limitations apply to ensure Prisma Client remains consistent with the behavior of the underlying database.

¥Prisma ORM treats all view blocks as read-only representations of database queries rather than true tables. Because of this, several limitations apply to ensure Prisma Client remains consistent with the behavior of the underlying database.

No identifiers

Views are virtual tables and do not have inherent primary keys.Hence, you cannot define @id, @@id attributes on a view block.

No indexes

Because views are virtual tables, they cannot have indexes.Therefore, @index and @@index cannot be defined on view blocks.

Unsafe `@unique` attributes

While Prisma ORM lets you place @unique and @@unique attributes on views, the underlying database and Prisma do not enforce those constraints.Multiple rows can therefore share the same value for a supposedly unique field.

Neither the database nor Prisma ORM enforce the unique constraint expressed by that attribute.

The purpose of the @unique attribute in this case is only to enable relationships across views as well as findUnique queries and cursor-based pagination in Prisma Client.

Disabled write queries

所有写入操作（create、update、delete、upsert）均已禁用，并且不会在 Prisma 客户端中生成。

¥All write operations (create, update, delete, upsert) are disabled and not generated in the Prisma Client.

启用 views 预览功能​

在底层数据库中创建视图​

将视图与 Prisma Migrate 和 db push 结合使用​

将视图添加到你的 Prisma 架构​

手写​

定义 view 块​

定义字段​

使用内省​

views 目录​

Prisma 客户端中的查询视图​

特殊类型的视图​

可更新的视图​

物化视图​

局限性​

No identifiers​

No indexes​

Unsafe @unique attributes​

Disabled write queries​