Mongo查找数组包含给定数组的x值的文档 [英] Mongo find documents where array contains x values of given array
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问题描述
我有一个包含类似文档的集合.实体字段没有在每个文档中设置,具有不同的值:
I have a collection which has documents like that one. The entity field is not set in each document and has different values:
{
"_id" : ObjectId("5388cfbdec82ba7cd5438635"),
"name" : "Name1",
"entity" : [
"Entity1",
"Entity2",
"Entity4",
"Entity5"
]
}
现在我想找到包含给定数组的 x 值的所有文档:["Entity1","Entity2","Entity3","Entity4"]
Now I want to find all documents which contains exactly x values of the given array : ["Entity1","Entity2","Entity3","Entity4"]
对于上面发布的文档,Entity1、Entity2、Entity4 的值是匹配的:
For the document posted above the values Entity1, Entity2, Entity4 are matching:
- x = 4 不应该找到文档(3 个匹配值,但 x 为 4)
- 应该找到 x = 3 个文档(3 个匹配 -> 大小 = x)
- x = 2 不应该找到文档(3 个匹配值,但 x 为 2)
- x = 1 不应该找到文档(3 个匹配值,但 x 为 1)
推荐答案
您可以为此使用 .aggregate
.这可能是您正在寻找的:
You can use .aggregate
for this. This is probably what you're looking for:
var y = ["Entity1", "Entity2", "Entity3", "Entity4"];
db.col.aggregate([
{
$project :
{
_id : 1,
name : 1,
entity : 1,
x : {
$size : {
$ifNull: [{$setIntersection : ["$entity", y]}, []]
}
}
}
},
{ $match : { x : 3 } }
]);
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