I have a collection in Mongo
{
"_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
}
]
}
I want to retrieve all elements having points = 85 and bonus = 20. Query will be
db.temp2.find({"points":{"points":85,"bonus":20}})
it returns documents with id : 1 and 2.
Now if i want to retrieve elements having ( points=85 and bonus = 20 ) and another sub-documents with {points=85 and bonus > 10). basically i want to retrieve element with id = 2
if query is
db.temp2.find({$and:[{"points":{"points":85,"bonus":20}},{"points":{"points":64,"bonus":{$gte:10}}}]}).pretty()
it gives no results whereas query
db.temp2.find({$and:[{"points":{"$elemMatch":{"points":85,"bonus":20}}},{"points":{"$elemMatch":{"points":64,"bonus":{$gte:10}}}}]})
gives me id=2.
Same thing i tried with anther sets
[
{
"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"
}
]
}
]
and if you want to find out elements having
"tags": [
{
"k": "group",
"v": "dev"
},
{
"k": "color",
"v": "blue"
}
]
query :
db.temp4.find({$and:[{"tags":{"k":"group","v":"dev"}},{"tags":{"k":"color","v":"blue"}}]})
and
db.temp4.find({$and:[{"tags":{"$elemMatch":{"k":"group","v":"dev"}}},{"tags":{"$elemMatch":{"k":"color","v":"blue"}}}]})
in both case you will get response.
Please help me to understand when to use $elemMatch and "$and".
Thanks in advance. Sorry for grammatical mistakes.
The below query should work. As it is an embedded array, the "points.bonus" and "points.points" should be referred like this when $gte is used.
db.collection.find({$and:[{"points":{"points":85,"bonus":20}}, {"points.points" : 64, "points.bonus" : {$gte : 10}}]})
In the second example, there is no $gte. So, you are getting response for both queries.