How to query Elasticsearch datasource in Grafana?

[ZahraZare]

I want to use an index in Elasticsearch as a data source in Grafana. But I can't query it and extract a specific field from it. I want to have only the data of the fields I want as output from among several fields in this data source, like an RDBMs where columns can be selected. in elasticsearch, By default, a GET request will return the whole document, as stored in the _source field. Individual fields can be requested by using the _source parameter. Multiple fields can be specified in a comma-separated list:

GET /website/blog/123?_source=title,text

But when I use this query in Grafana, nothing is displayed in the output.

 timestamp: * AND _source=DTLS_MA

This query says to display only the DTLS_MA field values in the output for all days (Because each index document is used for a specific day. So I set the value of my timestamp column equal to * to fetch all the documents) The field DTLS_MA is a dictionary like below:

"DTLS_MA" : {
            "IS_AVAILABLE" : true,
            "VOICE_DIFF" : 0,
            "VOICE_CNT" : 157720612,
            "VSMS_DIFF" : null,
            "VSMS_CNT" : null,
            "SMS_DIFF" : 0,
            "SMS_CNT" : 208672130,
            "HSDP_DIFF" : null,
            "HSDP_CNT" : null,
            "GPRS_DIFF" : 0,
            "GPRS_CNT" : 942823463,
            "RBT_DIFF" : null,
            "RBT_CNT" : null,
            "CMN_DIFF" : null,
            "CMN_CNT" : null,
            "MVPN_DIFF" : null,
            "MVPN_CNT" : null,
            "MVPN_RTC_DIFF" : null,
            "MVPN_RTC_CNT" : null,
            "COMPOSITE_DIFF" : null,
            "COMPOSITE_CNT" : null,
            "MMS_DIFF" : null,
            "MMS_CNT" : null
          }