Elasticsearch filtering with input array where - elasticsearch

Question

Our requirement is to filter objects by an array field of data by giving an input array to elasticsearch. Any combination input array elements is match with mentions array.
Small example
data:[
{"name": "xxxx", "mentions": ["X", "Y"]},
{"name": "yyyy", "mentions": ["K", "L", "M"]},
{"name": "zzz", "mentions": ["X", "L"]},
]
Input: [X, Y, K, L]
Output:[
{"name": "xxxx", "mentions": ["X", "Y"]},
{"name": "zzz", "mentions": ["X", "L"]}
]
Objects must be filtered according to mentions field, where each member of mentions array must be in the given input array, if there is any inconsistency, then ignore the object.
Terms query or bool with must field is not solving our problem.

Answer 1

A very simplistic solution is to make use of a Regex Expression in a Regex Query:
Below is how your query would be:
POST <your_index_name>/_search
{
"query": {
"bool": {
"must_not": [ <---- Note this.
{
"regexp": {
"mentions": "[^XYKL]" <---- Note this.
}
}
]
}
}
}
Square Brackets [...] would mean to match one of the characters present.
What I've done is simply used a Negate Character ^ inside the bracket and wrapped that Regex Logic inside a must_not clause of a Bool Query and it should give you what you are looking for.
The query would only return documents with values X Y K L values. Any other values barring that, it would not return those documents.
Note that I'm assuming the field mentions is of type keyword.