数据库-MongoDB聚合运算符；$dateToString

$dateToString聚合运算符按用户指定的格式将日期对象转为字符串。

语法

{
     $dateToString: {
    
    date: <dateExpression>,
    format: <formatString>,
    timezone: <tzExpression>,
    onNull: <expression>
} }

字段说明：

使用

格式指示符

<formatString>格式指示符可以是下面的值：

举例

集合sales有下面的文档：

{
    
  "_id" : 1,
  "item" : "abc",
  "price" : 10,
  "quantity" : 2,
  "date" : ISODate("2014-01-01T08:15:39.736Z")
}

下面的聚合使用$dateToString返回date字段格式化后的字符串：

db.sales.aggregate(
   [
     {
    
       $project: {
    
          yearMonthDayUTC: {
     $dateToString: {
     format: "%Y-%m-%d", date: "$date" } },
          timewithOffsetNY: {
     $dateToString: {
     format: "%H:%M:%S:%L%z", date: "$date", timezone: "America/New_York"} },
          timewithOffset430: {
     $dateToString: {
     format: "%H:%M:%S:%L%z", date: "$date", timezone: "+04:30" } },
          minutesOffsetNY: {
     $dateToString: {
     format: "%Z", date: "$date", timezone: "America/New_York" } },
          minutesOffset430: {
     $dateToString: {
     format: "%Z", date: "$date", timezone: "+04:30" } },
          abbreviated_month: {
     $dateToString: {
    format: "%b", date: "$date", timezone: "+04:30" } },
          full_month: {
     $dateToString: {
     format: "%B", date: "$date", timezone: "+04:30" } }
       }
     }
   ]
)

执行的结果如下：

{
    
   "_id" : 1,
   "yearMonthDayUTC" : "2014-01-01",
   "timewithOffsetNY" : "03:15:39:736-0500",
   "timewithOffset430" : "12:45:39:736+0430",
   "minutesOffsetNY" : "-300",
   "minutesOffset430" : "270",
   "abbreviated_month": "Jan",
   "full_month": "January"
}