如何在文档中查找包含数组中所有元素的文档？

Question

Hello I want to kno if is possible do a query for retrieve documents like this

Document

[
{
...
id:1
tags:['a', 'b', 'c']
...
},
{
...
id:2
tags:['b', 'c']
...
},
{
...
id:3
tags:['d']
...
}
]

findone({tags:{$all:['a', 'b']}}) -> 1 because a and b are only in doc 1 findone({tags:{$all:['b']}}) -> 1, 2 because b are only in doc 2 findone({tags:{$all:['a', 'b', 'd']}}) -> nothing, because any document has all tags inside array findone({tags:{$all:['d']}}) -> 3 because d are only in doc 3

There are any way of do this query?

Thanks

Answer 1

Query

• you can use $setDifference
• if empty (setDifference your_array "$tags") => tags has all the elements, and filter is true

Test code here

aggregate(
[{"$match": 
    {"$expr": 
      {"$eq": [{"$setDifference": [["a", "b", "d"], "$tags"]}, []]}}}])