[[search-validate]]
== Validate API

The validate API allows a user to validate a potentially expensive query
without executing it. The following example shows how it can be used:

[source,js]
--------------------------------------------------
curl -XPUT 'http://localhost:9200/twitter/tweet/1' -d '{
    "user" : "kimchy",
    "post_date" : "2009-11-15T14:12:12",
    "message" : "trying out Elastic Search"
}'
--------------------------------------------------

When the query is valid, the response contains `valid:true`:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/twitter/_validate/query?q=user:foo'
{"valid":true,"_shards":{"total":1,"successful":1,"failed":0}}
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Or, with a request body:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/twitter/tweet/_validate/query' -d '{
  "filtered" : {
    "query" : {
      "query_string" : {
        "query" : "*:*"
      }
    },
    "post_filter" : {
      "term" : { "user" : "kimchy" }
    }
  }
}'
{"valid":true,"_shards":{"total":1,"successful":1,"failed":0}}
--------------------------------------------------

If the query is invalid, `valid` will be `false`. Here the query is
invalid because ElasticSearch knows the post_date field should be a date
due to dynamic mapping, and 'foo' does not correctly parse into a date:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/twitter/tweet/_validate/query?q=post_date:foo'
{"valid":false,"_shards":{"total":1,"successful":1,"failed":0}}
--------------------------------------------------

An `explain` parameter can be specified to get more detailed information
about why a query failed:

[source,js]
--------------------------------------------------
curl -XGET 'http://localhost:9200/twitter/tweet/_validate/query?q=post_date:foo&pretty=true&explain=true'
{
  "valid" : false,
  "_shards" : {
    "total" : 1,
    "successful" : 1,
    "failed" : 0
  },
  "explanations" : [ {
    "index" : "twitter",
    "valid" : false,
    "error" : "org.elasticsearch.index.query.QueryParsingException: [twitter] Failed to parse; org.elasticsearch.ElasticSearchParseException: failed to parse date field [foo], tried both date format [dateOptionalTime], and timestamp number; java.lang.IllegalArgumentException: Invalid format: \"foo\""
  } ]
}
--------------------------------------------------