db.createView() (mongosh method方法)

An array that consists of the aggregation pipeline stage(s). 由聚合管道阶段组成的数组。db.createView() creates the view by applying the specified pipeline to the source collection or view.db.createView()通过将指定的pipeline应用于source集合或视图来创建视图。

A view definition pipeline cannot include the $out or the $merge stage. 视图定义pipeline不能包含$out或$merge阶段。This restriction also applies to embedded pipelines, such as pipelines used in $lookup or $facet stages.此限制也适用于嵌入式管道，例如$lookup或$facet阶段中使用的管道。

The view definition is public; i.e. db.getCollectionInfos() and explain operations on the view will include the pipeline that defines the view. As such, avoid referring directly to sensitive fields and values in view definitions.视图定义是公开的；即，db.getCollectionInfos()和explain对视图的操作将包括定义视图的管道。因此，避免在视图定义中直接引用敏感字段和值。

Optional. 可选。Specifies the default collation for the view.指定视图的默认排序规则。

Collation allows users to specify language-specific rules for string comparison, such as rules for lettercase and accent marks.排序规则允许用户为字符串比较指定特定于语言的规则，例如字母大小写和重音标记的规则。

If the underlying source is a collection, the view does not inherit the collection's collation settings.如果底层source是一个集合，则视图不会继承该集合的排序规则设置。

If no collation is specified, the view's default collation is the "simple" binary comparison collator.如果没有指定排序规则，则视图的默认排序规则是“简单”二进制比较排序规则。

If the underlying source is another view, the view must specify the same collation settings.如果底层source是另一个视图，则该视图必须指定相同的排序规则设置。

The collation option has the following syntax:排序规则选项具有以下语法：

collation: {
   locale: <string>,
   caseLevel: <boolean>,
   caseFirst: <string>,
   strength: <int>,
   numericOrdering: <boolean>,
   alternate: <string>,
   maxVariable: <string>,
   backwards: <boolean>
}

When specifying collation, the locale field is mandatory; all other collation fields are optional. For descriptions of the fields, see Collation Document.指定排序规则时，locale字段是必填的；所有其他排序字段都是可选的。有关字段的描述，请参阅排序规则文档。