How to add a string variable to a JSON query in Javascript without adding extra escaping

Question

I'm having an issues in being able to add a string variable to a section of JSON, and when I pass the full JSON request to the server, the string variable that I added to the JSON always contains extra escape quotes and I don't know how to remove them on insertion.

I've tried using JSON.Parse(queryString) but I then get an exception saying an unexpected token.

The match queries I'm trying to add will vary in number depending on the qty of report filters applied, therefore I can't hard code the match queries in the JSON code block as they're shown in the commented out section.

Code sample:

var queryString = '{ "match": { "log.level": "Information" } }, { "match": { "metadata.log_event_category": "Open Id Connect" } }'

var request =
{
    "size": 0,
    "query": {
        "bool": {
            "must": [

                // Need to insert a string variable here that would contain the match queries commented out below...
                // queryString, // doesnt work, adding the var here results in extra escapes
                // JSON.parse(queryString), doesnt work!

                // If I manually write in the match queries below then everything goes through OK
                //{ "match": { "log.level": "Information" } },
                //{ "match": { "metadata.log_event_category": "Open Id Connect" } },
                {
                    "range": {
                        "@timestamp": {
                            "gte": chartArray[0].dateTimeFrom,
                            "lte": chartArray[0].dateTimeTo
                        }
                    }
                }
            ]
        }
    },
    "aggs": {
        "myAggName": {
            "date_histogram": {
                "field": "@timestamp",
                [elasticIntervalType]: elasticIntervalUnits,
                "format": chartArray[0].scaleLabelAttributes
            }
        },
    }
}

Screenshot shows that I'm getting extra escape quotes from the match queries when sending to the server, but I need these to be removed:

Below is a screenshot of a working example but I'm trying to replicate building this equivalent request in javascript in order to pass to my controller and send off to Elastic Search.

JSON has a fixed set of rules. `queryString` does not fulfill these rules, hence it is not valid -> _"...an exception saying an unexpected token"_ — Andreas, Aug 27 '21 at 17:26
`must` is an array of objects and not an array of invalid JSON -> [What is the difference between JSON and Object Literal Notation?](https://stackoverflow.com/questions/2904131/what-is-the-difference-between-json-and-object-literal-notation) — Andreas, Aug 27 '21 at 17:27
[How do I ask a good question?](https://stackoverflow.com/help/how-to-ask): _"**DO NOT post images of code, data, error messages, etc.** - copy or type the text into the question. Please reserve the use of images for diagrams or demonstrating rendering bugs, things that are impossible to describe accurately via text."_ — Andreas, Aug 27 '21 at 17:35

score 0 · Answer 1 · answered Aug 27 '21 at 17:42

0

It looks like you could just add square brackets around the querystring to make json.parse work. Try:

var queryString = '{ "match": { "log.level": "Information" } }, { "match": { "metadata.log_event_category": "Open Id Connect" } }'

const must = JSON.parse(“[“ + queryString + ”]”);
must.push({
  "range": {
    "@timestamp": {
      "gte": chartArray[0].dateTimeFrom,
      "lte": chartArray[0].dateTimeTo
    }
  }
});


var request =
{
    "size": 0,
    "query": {
        "bool": {
            "must": must
        }
    },
    "aggs": { //etc }
};

answered Aug 27 '21 at 17:42

James

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Hi James, thanks for your reply, I'm finding that the double quotes shown in JSON.parse(“[“ + queryString + ”]”); is giving me squiggly line message "(JS) invalid Character" – OJB1 Aug 27 '21 at 17:46
Tried your example, unfortunately I get the the same issue where it tries to parse the queryString. Error message says "VM1344:1 Uncaught SyntaxError: Unexpected token at JSON.parse ()" What I can't figure out is when I manually write the match queries into the main request, I don't have the issues, its when try to insert them as a variable. thx – OJB1 Aug 27 '21 at 17:54

score 0 · Accepted Answer · answered Aug 27 '21 at 18:19

I had to split the match queries into separate items, then push them individually into the JSON request.

var must = [];

must.push(JSON.parse('{ "match": { "log.level": "Information" } }'))
must.push(JSON.parse('{ "match": { "metadata.log_event_category": "Open Id Connect" } }'))
must.push({
    "range": {
        "@timestamp": {
            "gte": chartArray[0].dateTimeFrom,
            "lte": chartArray[0].dateTimeTo
        }
    }
});

var request =
{
    "size": 0,
    "query": {
        "bool": {
            "must": must
        }
    },
    "aggs": {
        "myAggName": {
            "date_histogram": {
                "field": "@timestamp",
                [elasticIntervalType]: elasticIntervalUnits,
                "format": chartArray[0].scaleLabelAttributes
            }
        },
    }
}

How to add a string variable to a JSON query in Javascript without adding extra escaping

2 Answers2