Projection Operators投影算子

Note

find() operations on views do not support the following projection operators:视图上的find()操作不支持以下投影运算符：

Note

For details on specific operator, including syntax and examples, click on the specific operator to go to its reference page.有关特定运算符的详细信息，包括语法和示例，请单击特定运算符以转到其参考页。

Name名称Description描述
$ Projects the first element in an array that matches the query condition.投影数组中与查询条件匹配的第一个元素。
$elemMatch Projects the first element in an array that matches the specified $elemMatch condition.投影数组中与指定的$elemMatch条件匹配的第一个元素。
$meta Projects the available per-document metadata.投影每个文档可用的元数据。
$slice Limits the number of elements projected from an array. 限制从阵列投影的元素数。Supports skip and limit slices.支持跳过和限制切片。