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Search Template

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Search Template

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The /_search/template endpoint allows to use the mustache language to pre render search requests, before they are executed and fill existing templates with template parameters.

GET /_search/template
{
    "template" : {
      "query": { "match" : { "{{my_field}}" : "{{my_value}}" } },
      "size" : "{{my_size}}"
    },
    "params" : {
        "my_field" : "foo",
        "my_value" : "bar",
        "my_size" : 5
    }
}

For more information on how Mustache templating and what kind of templating you can do with it check out the online documentation of the mustache project.

More template examples

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Filling in a query string with a single value

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GET /_search/template
{
    "template": {
        "query": {
            "match": {
                "title": "{{query_string}}"
            }
        }
    },
    "params": {
        "query_string": "search for these words"
    }
}

Passing an array of strings

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GET /_search/template
{
  "template": {
    "query": {
      "terms": {
        "status": [
          "{{#status}}",
          "{{.}}",
          "{{/status}}"
        ]
      }
    }
  },
  "params": {
    "status": [ "pending", "published" ]
  }
}

which is rendered as:

{
"query": {
  "terms": {
    "status": [ "pending", "published" ]
  }
}

Default values

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A default value is written as {{var}}{{^var}}default{{/var}} for instance:

{
  "template": {
    "query": {
      "range": {
        "line_no": {
          "gte": "{{start}}",
          "lte": "{{end}}{{^end}}20{{/end}}"
        }
      }
    }
  },
  "params": { ... }
}

When params is { "start": 10, "end": 15 } this query would be rendered as:

{
    "range": {
        "line_no": {
            "gte": "10",
            "lte": "15"
        }
  }
}

But when params is { "start": 10 } this query would use the default value for end:

{
    "range": {
        "line_no": {
            "gte": "10",
            "lte": "20"
        }
    }
}

Conditional clauses

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Conditional clauses cannot be expressed using the JSON form of the template. Instead, the template must be passed as a string. For instance, let’s say we wanted to run a match query on the line field, and optionally wanted to filter by line numbers, where start and end are optional.

The params would look like:

{
    "params": {
        "text":      "words to search for",
        "line_no": { 
            "start": 10, 
            "end":   20  
        }
    }
}

All three of these elements are optional.

We could write the query as:

{
  "query": {
    "filtered": {
      "query": {
        "match": {
          "line": "{{text}}" 
        }
      },
      "filter": {
        {{#line_no}} 
          "range": {
            "line_no": {
              {{#start}} 
                "gte": "{{start}}" 
                {{#end}},{{/end}} 
              {{/start}} 
              {{#end}} 
                "lte": "{{end}}" 
              {{/end}} 
            }
          }
        {{/line_no}} 
      }
    }
  }
}

	Fill in the value of param `text`
	Include the `range` filter only if `line_no` is specified
	Include the `gte` clause only if `line_no.start` is specified
	Fill in the value of param `line_no.start`
	Add a comma after the `gte` clause only if `line_no.start` AND `line_no.end` are specified
	Include the `lte` clause only if `line_no.end` is specified
	Fill in the value of param `line_no.end`

As written above, this template is not valid JSON because it includes the section markers like {{#line_no}}. For this reason, the template should either be stored in a file (see Pre-registered template) or, when used via the REST API, should be written as a string:

"template": "{\"query\":{\"filtered\":{\"query\":{\"match\":{\"line\":\"{{text}}\"}},\"filter\":{{{#line_no}}\"range\":{\"line_no\":{{{#start}}\"gte\":\"{{start}}\"{{#end}},{{/end}}{{/start}}{{#end}}\"lte\":\"{{end}}\"{{/end}}}}{{/line_no}}}}}}"

Pre-registered template

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You can register search templates by storing it in the config/scripts directory, in a file using the .mustache extension. In order to execute the stored template, reference it by it’s name under the template key:

GET /_search/template
{
    "template": {
        "file": "storedTemplate" 
    },
    "params": {
        "query_string": "search for these words"
    }
}

Name of the the query template in config/scripts/, i.e., storedTemplate.mustache.

You can also register search templates by storing it in the elasticsearch cluster in a special index named .scripts. There are REST APIs to manage these indexed templates.

POST /_search/template/<templatename>
{
    "template": {
        "query": {
            "match": {
                "title": "{{query_string}}"
            }
        }
    }
}

This template can be retrieved by

GET /_search/template/<templatename>

which is rendered as:

{
    "template": {
        "query": {
            "match": {
                "title": "{{query_string}}"
            }
        }
    }
}

This template can be deleted by

DELETE /_search/template/<templatename>

To use an indexed template at search time use:

GET /_search/template
{
    "template": {
        "id": "templateName" 
    },
    "params": {
        "query_string": "search for these words"
    }
}

Name of the the query template stored in the .scripts index.

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