Date Range Query using SearchTemplate in Elasticse

We have a scenario where we have to do range query with "OR" condition. It is working fine, with one query, but getting error while triggering with multiple query.

POST _scripts/dateTemplate
{
  "script": {
    "lang": "mustache",
    "source": """
        {
        "query": {
            "bool": {
                "must": {
                "query_string": {
                    "query": "title:({{searchkeyword}})"
                }
            },
            "filter": {
                "bool":{
                    "must":[
                        {
                            "match_all": {}
                        }
                        {{#f_url}} , {
                            "terms" : {
                                "f_url": [{{#toJson}}f_url{{/toJson}} ]
                                }
                            }
                        {{/f_url}}
                    ],
                    "should":[
                        {{#since}}
                            {
                                "range": {
                                    "{{since}}": {
                                        {{#from}}"from": "{{from}}"{{#to}},{{/to}}{{/from}}
                                        {{#to}}"to":"{{to}}"{{/to}}
                                    }
                                }
                            }
                        {{/since}}
                    ]
                }
            }
        }
    }
    }
"""
  }
}

Query while calling the template

POST _search/template
{
  "id": "dateTemplate",
  "params": {
    "searchkeyword": "*",
    "since":[ {
      "since":"@timestamp",
      "from": "2018-06-01"
    },
     {
      "since":"@timestamp",
      "from": "2018-06-08"
    }
    ]
  }
}

Error

{
  "error": {
    "root_cause": [
      {
        "type": "json_parse_exception",
        "reason": "Unexpected character ('{' (code 123)): was expecting comma to separate Array entries\n at [Source: \t\t{\n\t\t\"query\": {\n\t\t\t\"bool\": {\n\t\t\t\t\"must\": {\n\t\t\t\t\"query_string\": {\n\t\t\t\t\t\"query\": \"title:(*)\"\n\t\t\t\t}\n\t\t\t},\n\t\t\t\"filter\": {\n\t\t\t\t\"bool\":{\n\t\t\t\t\t\"must\":[\n\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\"match_all\": {}\n\t\t\t\t\t\t}\n\t\t\t\t\t],\n\t\t\t\t\t\"should\":[\n\t\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\t\"range\": {\n\t\t\t\t\t\t\t\t\t\"@timestamp\": {\n\t\t\t\t\t\t\t\t\t\t\"from\": \"2018-06-01\"\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\t\"range\": {\n\t\t\t\t\t\t\t\t\t\"@timestamp\": {\n\t\t\t\t\t\t\t\t\t\t\"from\": \"2018-06-08\"\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t}\n\t\t\t\t\t]\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\t}; line: 25, column: 9]"
      }
    ],
    "type": "json_parse_exception",
    "reason": "Unexpected character ('{' (code 123)): was expecting comma to separate Array entries\n at [Source: \t\t{\n\t\t\"query\": {\n\t\t\t\"bool\": {\n\t\t\t\t\"must\": {\n\t\t\t\t\"query_string\": {\n\t\t\t\t\t\"query\": \"title:(*)\"\n\t\t\t\t}\n\t\t\t},\n\t\t\t\"filter\": {\n\t\t\t\t\"bool\":{\n\t\t\t\t\t\"must\":[\n\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\"match_all\": {}\n\t\t\t\t\t\t}\n\t\t\t\t\t],\n\t\t\t\t\t\"should\":[\n\t\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\t\"range\": {\n\t\t\t\t\t\t\t\t\t\"@timestamp\": {\n\t\t\t\t\t\t\t\t\t\t\"from\": \"2018-06-01\"\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t{\n\t\t\t\t\t\t\t\t\"range\": {\n\t\t\t\t\t\t\t\t\t\"@timestamp\": {\n\t\t\t\t\t\t\t\t\t\t\"from\": \"2018-06-08\"\n\t\t\t\t\t\t\t\t\t\t\n\t\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t\t}\n\t\t\t\t\t\t\t}\n\t\t\t\t\t]\n\t\t\t\t}\n\t\t\t}\n\t\t}\n\t}\n\t}; line: 25, column: 9]"
  },
  "status": 500
}

Same if I add it in must clause, it is working perfectly with "AND" condition. Can you please help in framing the template with both "AND" and "OR" Condition?

You're almost there, you simply need to let mustache know when the last element of the array is reached. So your template should look like this (i.e. we add a comma after each element, except the last one):

  ...
                "should":[
                    {{#since}}
                        {
                            "range": {
                                "{{since}}": {
                                    {{#from}}"from": "{{from}}"{{#to}},{{/to}}{{/from}}
                                    {{#to}}"to":"{{to}}"{{/to}}
                                }
                            }
                        }{{^last}},{{/last}}                <-- modify this line
                    {{/since}}
                ]
  ...

And then simply modify your call to include the last flag to the last element of the since array:

POST _search/template
{
  "id": "dateTemplate",
  "params": {
    "searchkeyword": "*",
    "since":[ {
      "since":"@timestamp",
      "from": "2018-06-01"
    },
     {
      "since":"@timestamp",
      "from": "2018-06-08",
      "last": true                                         <-- add this line
    }
    ]
  }
}