How to exclude {} in a field from a search

Question

I have a record like

"log": {
      "Level": null,
      "Message": "blah",
      "StackTrace": "{}"
}

I have tried something like

{
    "query": {
        "bool": {
            "must_not": [{
                "match": {
                    "log.StackTrace": {
                        "query": "{}",
                        "type": "phrase"
                    }
                }
            }]
        }

    }
}

But still can't exclude this record from the search result

Answer 1

Make it a term query inside the must_not clause and use log.StackTrace.Keyword as the field

{ "query": { "bool": { "must_not": { "term" { "log.StackTrace.keyword": "{}" } } }}