elasticsearch/docs/reference/query-dsl/has-child-query.asciidoc

[[query-dsl-has-child-query]]
=== Has Child Query

The `has_child` filter accepts a query and the child type to run against, and
results in parent documents that have child docs matching the query. Here is
an example:

[source,js]
--------------------------------------------------
{
    "has_child" : {
        "type" : "blog_tag",
        "query" : {
            "term" : {
                "tag" : "something"
            }
        }
    }
}
--------------------------------------------------

[float]
==== Scoring capabilities

The `has_child` also has scoring support. The
supported score modes are `min`, `max`, `sum`, `avg` or `none`. The default is
`none` and yields the same behaviour as in previous versions. If the
score mode is set to another value than `none`, the scores of all the
matching child documents are aggregated into the associated parent
documents. The score type can be specified with the `score_mode` field
inside the `has_child` query:

[source,js]
--------------------------------------------------
{
    "has_child" : {
        "type" : "blog_tag",
        "score_mode" : "min",
        "query" : {
            "term" : {
                "tag" : "something"
            }
        }
    }
}
--------------------------------------------------

[float]
==== Min/Max Children

The `has_child` query allows you to specify that a minimum and/or maximum
number of children are required to match for the parent doc to be considered
a match:

[source,js]
--------------------------------------------------
{
    "has_child" : {
        "type" : "blog_tag",
        "score_mode" : "min",
        "min_children": 2, <1>
        "max_children": 10, <1>
        "query" : {
            "term" : {
                "tag" : "something"
            }
        }
    }
}
--------------------------------------------------
<1> Both `min_children` and `max_children` are optional.

The  `min_children` and `max_children` parameters can be combined with
the `score_mode` parameter.

[float]
==== Ignore Unmapped

When set to `true` the `ignore_unmapped` option will ignore an unmapped `type`
and will not match any documents for this query. This can be useful when
querying multiple indexes which might have different mappings. When set to
`false` (the default value) the query will throw an exception if the `type`
is not mapped.