Class Db

The Db class is a class that represents a MongoDB Database.Db类是一个表示MongoDB数据库的类。

Example

import { MongoClient } from 'mongodb';

interface Pet {
  name: string;
  kind: 'dog' | 'cat' | 'fish';
}

const client = new MongoClient('mongodb://localhost:27017');
const db = client.db();

// Create a collection that validates our union
await db.createCollection<Pet>('pets', {
  validator: { $expr: { $in: ['$kind', ['dog', 'cat', 'fish']] } }
})

Constructors构造函数

constructor构造函数

Properties属性

client SYSTEM_COMMAND_COLLECTION SYSTEM_INDEX_COLLECTION SYSTEM_JS_COLLECTION SYSTEM_NAMESPACE_COLLECTION SYSTEM_PROFILE_COLLECTION SYSTEM_USER_COLLECTION

Accessors访问器

bsonOptions databaseName namespace options readConcern readPreference secondaryOk timeoutMS writeConcern

Methods方法

admin aggregate collection collections command createCollection createIndex dropCollection dropDatabase indexInformation listCollections profilingLevel removeUser renameCollection runCursorCommand setProfilingLevel stats watch

Constructors构造函数

constructor构造函数

  • new Db(client, databaseName, options?): Db

  • Creates a new Db instance.创建一个新的Db实例。

    Db name cannot contain a dot, the server may apply more restrictions when an operation is run.Db名称不能包含点，服务器在运行操作时可能会应用更多限制。

    Parameters参数

    • client: MongoClient

      The MongoClient for the database.数据库的MongoClient。

    • databaseName: string

      The name of the database this instance represents.此实例所代表的数据库的名称。

    • Optionaloptions: DbOptions

      Optional settings for Db construction.Db构造的可选设置。

    Returns 返回Db

Properties属性

Readonlyclient

client: MongoClient

Gets the MongoClient associated with the Db.获取与数据库关联的MongoClient。

StaticSYSTEM_COMMAND_COLLECTION

SYSTEM_COMMAND_COLLECTION: string = CONSTANTS.SYSTEM_COMMAND_COLLECTION

StaticSYSTEM_INDEX_COLLECTION

SYSTEM_INDEX_COLLECTION: string = CONSTANTS.SYSTEM_INDEX_COLLECTION

StaticSYSTEM_JS_COLLECTION

SYSTEM_JS_COLLECTION: string = CONSTANTS.SYSTEM_JS_COLLECTION

StaticSYSTEM_NAMESPACE_COLLECTION

SYSTEM_NAMESPACE_COLLECTION: string = CONSTANTS.SYSTEM_NAMESPACE_COLLECTION

StaticSYSTEM_PROFILE_COLLECTION

SYSTEM_PROFILE_COLLECTION: string = CONSTANTS.SYSTEM_PROFILE_COLLECTION

StaticSYSTEM_USER_COLLECTION

SYSTEM_USER_COLLECTION: string = CONSTANTS.SYSTEM_USER_COLLECTION

Accessors访问器

bsonOptions

databaseName

  • get databaseName(): string

  • Returns 返回string

namespace

  • get namespace(): string

  • Returns 返回string

options

readConcern

readPreference

  • get readPreference(): ReadPreference

  • The current readPreference of the Db. If not explicitly defined for this Db, will be inherited from the parent MongoClientDb的当前readPreference。如果没有为此数据库明确定义，将从父级MongoClient继承

    Returns 返回ReadPreference

secondaryOk

  • get secondaryOk(): boolean

  • Check if a secondary can be used (because the read preference is not set to primary)检查是否可以使用辅助选项（因为读取首选项未设置为主选项）

    Returns 返回boolean

timeoutMS

  • get timeoutMS(): undefined | number

  • Returns 返回undefined | number

writeConcern

Methods方法

admin

aggregate

  • aggregate<T>(pipeline?, options?): AggregationCursor<T>

  • Execute an aggregation framework pipeline against the database.对数据库执行聚合框架管道。

    Type Parameters类型参数

    Parameters参数

    • pipeline: Document[] = []

      An array of aggregation stages to be executed要执行的一系列聚合阶段

    • Optionaloptions: AggregateOptions

      Optional settings for the command命令的可选设置

    Returns 返回AggregationCursor<T>

collection

  • collection<TSchema>(name, options?): Collection<TSchema>

  • Returns a reference to a MongoDB Collection. If it does not exist it will be created implicitly.返回对MongoDB集合的引用。如果它不存在，它将隐式创建。

    Collection namespace validation is performed server-side.集合命名空间验证在服务器端执行。

    Type Parameters类型参数

    Parameters参数

    • name: string

      the collection name we wish to access.我们希望访问的集合名称。

    • options: CollectionOptions = {}

    Returns 返回Collection<TSchema>

    return the new Collection instance返回新的Collection实例

collections

command

  • command(command, options?): Promise<Document>

  • Execute a command执行命令

    Parameters参数

    Returns 返回Promise<Document>

    Remarks

    This command does not inherit options from the MongoClient.此命令不继承MongoClient的选项。

    The driver will ensure the following fields are attached to the command sent to the server:驱动程序将确保以下字段附加到发送到服务器的命令中：

    • lsid - sourced from an implicit session or options.session来源于隐式会话或options.session
    • $readPreference - defaults to primary or can be configured by options.readPreference默认设置为主选项，也可以通过options.readPreference进行配置
    • $db - sourced from the name of this database来源于此数据库的名称

    If the client has a serverApi setting:如果客户端具有serverApi设置：

    • apiVersion
    • apiStrict
    • apiDeprecationErrors

    When in a transaction:在事务中：

    • readConcern - sourced from readConcern set on the TransactionOptions来源于TransactionOptions上的readConcern集
    • writeConcern - sourced from writeConcern set on the TransactionOptions来源于TransactionOptions上的writeConcern集

    Attaching any of the above fields to the command will have no effect as the driver will overwrite the value.将上述任何字段附加到命令都将无效，因为驱动程序将覆盖该值。

createCollection

  • createCollection<TSchema>(name, options?): Promise<Collection<TSchema>>

  • Create a new collection on a server with the specified options. Use this to create capped collections. 使用指定的选项在服务器上创建新集合。使用此选项创建上限集合。More information about command options available at 有关可用命令选项的更多信息，请访问/v8.3/reference/command/create/

    Collection namespace validation is performed server-side.集合命名空间验证在服务器端执行。

    Type Parameters类型参数

    Parameters参数

    • name: string

      The name of the collection to create要创建的集合的名称

    • Optionaloptions: CreateCollectionOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<Collection<TSchema>>

createIndex

  • createIndex(name, indexSpec, options?): Promise<string>

  • Creates an index on the db and collection.在数据库和集合上创建索引。

    Parameters参数

    • name: string

      Name of the collection to create the index on.要在其上创建索引的集合的名称。

    • indexSpec: IndexSpecification

      Specify the field to index, or an index specification指定要索引的字段或索引规范

    • Optionaloptions: CreateIndexesOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<string>

dropCollection

  • dropCollection(name, options?): Promise<boolean>

  • Drop a collection from the database, removing it permanently. New accesses will create a new collection.从数据库中删除一个集合，并将其永久删除。新的访问权限将创建新的集合。

    Parameters参数

    • name: string

      Name of collection to drop要删除的集合名称

    • Optionaloptions: DropCollectionOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<boolean>

dropDatabase

  • dropDatabase(options?): Promise<boolean>

  • Drop a database, removing it permanently from the server.删除数据库，将其从服务器中永久删除。

    Parameters参数

    Returns 返回Promise<boolean>

indexInformation

listCollections

profilingLevel

  • profilingLevel(options?): Promise<string>

  • Retrieve the current profiling Level for MongoDB检索MongoDB的当前分析级别

    Parameters参数

    Returns 返回Promise<string>

removeUser

  • removeUser(username, options?): Promise<boolean>

  • Remove a user from a database从数据库中删除用户

    Parameters参数

    • username: string

      The username to remove要删除的用户名

    • Optionaloptions: RemoveUserOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<boolean>

renameCollection

  • renameCollection<TSchema>(fromCollection, toCollection, options?): Promise<Collection<TSchema>>

  • Rename a collection.重命名集合。

    Type Parameters

    Parameters参数

    • fromCollection: string

      Name of current collection to rename要重命名的当前集合的名称

    • toCollection: string

      New name of of the collection集合的新名称

    • Optionaloptions: RenameOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<Collection<TSchema>>

    Remarks

    This operation does not inherit options from the MongoClient.此操作不继承MongoClient的选项。

runCursorCommand

  • runCursorCommand(command, options?): RunCommandCursor

  • A low level cursor API providing basic driver functionality:提供基本驱动程序功能的低级游标API：

    • ClientSession management管理
    • ReadPreference for server selectionReadPreference用于服务器选择
    • Running getMores automatically when a local batch is exhausted当本地批处理耗尽时自动运行getMores

    Parameters参数

    • command: Document

      The command that will start a cursor on the server.将在服务器上启动游标的命令。

    • Optionaloptions: RunCursorCommandOptions

      Configurations for running the command, bson options will apply to getMores运行命令的配置，bson选项将应用于getMores

    Returns 返回RunCommandCursor

setProfilingLevel

  • setProfilingLevel(level, options?): Promise<ProfilingLevel>

  • Set the current profiling level of MongoDB设置MongoDB的当前分析级别

    Parameters参数

    • level: ProfilingLevel

      The new profiling level (off, slow_only, all).新的分析级别（关闭、仅限慢速、全部）。

    • Optionaloptions: SetProfilingLevelOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<ProfilingLevel>

stats

  • stats(options?): Promise<Document>

  • Get all the db statistics.

    Parameters参数

    • Optionaloptions: DbStatsOptions

      Optional settings for the command命令的可选设置

    Returns 返回Promise<Document>

watch

  • watch<TSchema, TChange>(pipeline?, options?): ChangeStream<TSchema, TChange>

  • Create a new Change Stream, watching for new changes (insertions, updates, replacements, deletions, and invalidations) in this database. Will ignore all changes to system collections.创建新的更改流，观察此数据库中的新更改（插入、更新、替换、删除和无效）。将忽略对系统集合的所有更改。

    Type Parameters类型参数

    • TSchema extends Document = Document

      Type of the data being detected by the change stream更改流检测到的数据类型

    • TChange extends Document = ChangeStreamDocument<TSchema>

      Type of the whole change stream document emitted发出的整个变更流文档的类型

    Parameters参数

    • pipeline: Document[] = []

      An array of pipeline stages through which to pass change stream documents. This allows for filtering (using $match) and manipulating the change stream documents.管道阶段的数组，通过这些阶段传递变更流文档。这允许筛选（使用$match）和操纵更改流文档。

    • options: ChangeStreamOptions = {}

      Optional settings for the command命令的可选设置

    Returns 返回ChangeStream<TSchema, TChange>

    Remarks

    watch() accepts two generic arguments for distinct use cases:watch()为不同的用例接受两个泛型参数：

    • The first is to provide the schema that may be defined for all the collections within this database第一个是提供可以为该数据库中的所有集合定义的模式
    • The second is to override the shape of the change stream document entirely, if it is not provided the type will default to ChangeStreamDocument of the first argument第二种方法是完全覆盖更改流文档的形状，如果没有提供，则类型将默认为第一个参数的ChangeStreamDocument

    Example

    In iterator mode, if a next() call throws a timeout error, it will attempt to resume the change stream. The next call can just be retried after this succeeds.在迭代器模式下，如果next()调用抛出超时错误，它将尝试恢复更改流。此操作成功后，可以重试下一个调用。

    const changeStream = collection.watch([], { timeoutMS: 100 });
    try {
        await changeStream.next();
    } catch (e) {
        if (e instanceof MongoOperationTimeoutError && !changeStream.closed) {
          await changeStream.next();
        }
        throw e;
    }

    Example

    In emitter mode, if the change stream goes timeoutMS without emitting a change event, it will emit an error event that returns a MongoOperationTimeoutError, but will not close the change stream unless the resume attempt fails. There is no need to re-establish change listeners as this will automatically continue emitting change events once the resume attempt completes.在发射器模式下，如果更改流过了timeoutMS而不发出更改事件，它将发出一个错误事件，返回MongoOperationTimeoutError，但除非恢复尝试失败，否则不会关闭更改流。无需重新建立更改侦听器，因为一旦恢复尝试完成，它将自动继续发出更改事件。

    const changeStream = collection.watch([], { timeoutMS: 100 });
    changeStream.on('change', console.log);
    changeStream.on('error', e => {
        if (e instanceof MongoOperationTimeoutError && !changeStream.closed) {
            // do nothing
        } else {
            changeStream.close();
        }
    });

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Constructors构造函数
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Accessors访问器
Methods方法