我在Mongo有一个集合
{
"_id": 1,
"favorites": {
"artist": "Picasso",
"food": "pizza"
},
"finished": [
17,
3
],
"badges": [
"blue",
"black"
],
"points": [
{
"points": 85,
"bo nus": 20
},
{
"points": 85,
"bonus": 10
}
]
}{
"_id": 2,
"favorites": {
"artist": "Miro",
"food": "meringue"
},
"finished": [
11,
25
],
"badges": [
"green"
],
"points": [
{
"points": 85,
"bonus": 20
},
{
"points": 64,
"bonus": 12
}
]
}{
"_id": 3,
"favorites": {
"artist": "Cassatt",
"food": "cake"
},
"finished": [
6
],
"badges": [
"blue",
"red"
],
"points": [
{
"points": 85,
"bonus": 8
},
{
"points": 55,
"bonus": 20
}
]
}{
"_id": 4,
"favorites": {
"artist": "Chagall",
"food": "chocolate"
},
"finished": [
5,
11
],
"badges": [
"red",
"black"
],
"points": [
{
"points": 53,
"bonus": 15
},
{
"points": 51,
"bonus": 15
}
]
}{
"_id": 5,
"favorites": {
"artist": "Noguchi",
"food": "nougat"
},
"finished": [
14,
6
],
"badges": [
"orange"
],
"points": [
{
"points": 71,
"bonus": 20
}
]
}{
"_id": 6,
"favorites": {
"food": "pizza",
"artist": "Picasso"
},
"finished": [
18,
12
],
"badges": [
"black",
"blue"
],
"points": [
{
"points": 78,
"b onus": 8
},
{
"points": 57,
"bonus": 7
}
]
}
我想要检索所有 points = 85和bonus = 20 的元素。 查询将是
db.temp2.find({"points":{"points":85,"bonus":20}})
它返回id为1和2的文档。
现在,如果我想要检索具有(points = 85和bonus = 20)的元素以及{points = 85和bonus>的其他子文档10)。基本上我想要检索id = 2
的元素如果查询
db.temp2.find({$and:[{"points":{"points":85,"bonus":20}},{"points":{"points":64,"bonus":{$gte:10}}}]}).pretty()
它没有给出结果而查询
db.temp2.find({$and:[{"points":{"$elemMatch":{"points":85,"bonus":20}}},{"points":{"$elemMatch":{"points":64,"bonus":{$gte:10}}}}]})
给我id = 2。
我尝试使用花药套装
[
{
"name": "User1",
"tags": [
{
"k": "group",
"v": "test"
},
{
"k": "color",
"v": "blue"
}
]
},
{
"name": "User2",
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "blue"
}
]
},
{
"name": "User3",
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "red"
}
]
}
]
如果你想找到有
的元素"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "blue"
}
]
查询:
db.temp4.find({$and:[{"tags":{"k":"group","v":"dev"}},{"tags":{"k":"color","v":"blue"}}]})
和
db.temp4.find({$and:[{"tags":{"$elemMatch":{"k":"group","v":"dev"}}},{"tags":{"$elemMatch":{"k":"color","v":"blue"}}}]})
在这两种情况下你都会得到回复。
请帮助我了解何时使用 $ elemMatch 和“$和”。
提前致谢。 对不起语法错误。
答案 0 :(得分:0)
以下查询应该有效。因为它是一个嵌入式数组,所以当使用 $gte
时,应该像这样引用“points.bonus”和“points.points”。
db.collection.find({$and:[{"points":{"points":85,"bonus":20}}, {"points.points" : 64, "points.bonus" : {$gte : 10}}]})
在第二个示例中,没有$gte
。所以,你得到了两个查询的回复。