我想放松2个领域,学校和家庭.
数据库结构就像;
{
"id" : 1,
"school" : [
{
"path" : "school1",
"code" : "code1",
},
{
"path" : "school2",
"code" : "code2",
},
{
"path" : "school3",
"code" : "code3",
},
{
"path" : "school4",
"code" : "code4",
}
],
"home" : [
{
"path" : "home1",
"code" : "homeCode1",
},
{
"path" : "home2",
"code" : "homeCode2",
},
]
}
我想放松学校和家庭领域,让他们每个人都这样;
{
"id" : 1,
"school" : [
{
"path" : "school1",
"code" : "code1",
}
},
{
"id" : 1,
"school" : [
{
"path" : "school2",
"code" : "code2",
}
},
{
"id" : 1,
"school" : [
{
"path" : "school3",
"code" : "code3",
}
},
{
"id" : 1,
"school" : [
{
"path" : "school4",
"code" : "code4",
}
},
{
"id" : 1,
"home" : [
{
"path" : "home1",
"code" : "homeCode1",
}
},
{
"id" : 1,
"home" : [
{
"path" : "home2",
"code" : "homeCode2",
}
}
我写的旨在获得上述格式的查询是;
db.collection.aggregate([
{$unwind: "$school"},
{$unwind: "$home"}
]).pretty()
但查询结果为对;
{
"id" : 1,
"school" : {
"path" : "school1",
"code" : "code1"
},
"home" : {
"path" : "home1",
"code" : "homeCode1"
}
}
{
"id" : 1,
"school" : {
"path" : "school1",
"code" : "code1"
},
"home" : {
"path" : "home2",
"code" : "homeCode2"
}
}
{
"id" : 1,
"school" : {
"path" : "school2",
"code" : "code2"
},
"home" : {
"path" : "home1",
"code" : "homeCode1"
}
}
{
"id" : 1,
"school" : {
"path" : "school2",
"code" : "code2"
},
"home" : {
"path" : "home2",
"code" : "homeCode2"
}
}
{
"id" : 1,
"school" : {
"path" : "school3",
"code" : "code3"
},
"home" : {
"path" : "home1",
"code" : "homeCode1"
}
}
{
"id" : 1,
"school" : {
"path" : "school3",
"code" : "code3"
},
"home" : {
"path" : "home2",
"code" : "homeCode2"
}
}
{
"id" : 1,
"school" : {
"path" : "school4",
"code" : "code4"
},
"home" : {
"path" : "home1",
"code" : "homeCode1"
}
}
{
"id" : 1,
"school" : {
"path" : "school4",
"code" : "code4"
},
"home" : {
"path" : "home2",
"code" : "homeCode2"
}
}
我怎样才能单独解开2个字段,而不是这个结果对格式?
最佳答案 这不是直接可能的.使用MongoDB 3.4,可能有一种解决方法. $facet可用于在同一文档的单个阶段中执行多组管道操作.它对你的情况很有用.
db.collection.aggregate({
'$facet': {
'school': [{
'$unwind': '$school'
}, {
'$project': {
_id: '1',
school: 1
}
}],
'home': [{
'$unwind': '$home'
}, {
'$project': {
_id: '1',
home: 1
}
}]
}
}, {
'$project': {
'schoolAndHome': {
'$setUnion': ['$school', '$home']
}
}
}, {
'$unwind': '$schoolAndHome'
}, {
'$replaceRoot': {
'newRoot': '$schoolAndHome'
}
})