如何在 mongoDB 2 或 3 中查询以下文档中的所有标签:
{
"_id" : ObjectId("55dc45017137a4e70b8b4569"),
"campainName" : "",
"themeName" : "theme1",
"emailListName" : "eiEmails",
"emailSubject" : "",
"emailFrom" : "",
"allNews" : [
{
"type" : "1",
"tag" : ['aa','bb','cc'],
"link" : "",
"image" : ""
}
]
},
{
"_id" : ObjectId("55dc45017137a4e70b8b4570"),
"campainName" : "",
"themeName" : "theme2",
"emailListName" : "afaeiEmails",
"emailSubject" : "",
"emailFrom" : "",
"allNews" : [
{
"type" : "1",
"tag" : ['da','db','dc'],
"link" : "",
"image" : ""
}
]
}
我需要这样的结果:
{['aa','bb','cc'], ['da','db','dc']}
我需要学说 odm 中的查询风格。