如何在mongodb中使用值作为键

Question

将此作为mongo find命令的输出

{ 
    "cust" : NumberInt(8388), 
    "key" : "T_SUB_CAT", 
    "value" : "98", 
    "tag1" : "T_RECENT_SUB_CAT_1"
},{ 
    "cust" : NumberInt(8388), 
    "key" : "T_SUB_CAT", 
    "value" : "109", 
    "tag1" : "T_RECENT_SUB_CAT_2"
},{ 
    "cust" : NumberInt(8388), 
    "key" : "T_SUB_CAT", 
    "value" : "6", 
    "tag1" : "T_RECENT_SUB_CAT_3"
}

如何使用聚合和$ project来获得结果这个

{ 
    "cust" : NumberInt(8388), 
    "T_RECENT_SUB_CAT_1" : "98", 
    "T_RECENT_SUB_CAT_2" : "109", 
    "T_RECENT_SUB_CAT_3" : "6"
}

请使用项目/汇总

帮助我

非常感谢

Answer 1

将所有结果放入var say cust2，

while(cust2.hasNext()){ 
var document = cust2.next(); db.<collection>.update( 
{ cust: document.cust, tag1:document.tag1 }, 
{ cust:document.cust , tag1:document.tag1 , 
key:document.key, value:document.value }, 
{upsert:true} 
) }