Fields

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Allows to selectively load specific fields for each document represented by a search hit. Defaults to load the internal _source field.

{
    "fields" : ["user", "postDate"],
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

The fields will automatically load stored fields (store mapping set to yes), or, if not stored, will load the _source and extract it from it (allowing to return nested document object).

* can be used to load all stored fields from the document.

An empty array will cause only the _id and _type for each hit to be returned, for example:

{
    "fields" : [],
    "query" : {
        "term" : { "user" : "kimchy" }
    }
}

Script fields can also be automatically detected and used as fields, so things like _source.obj1.obj2 can be used, though not recommended, as obj1.obj2 will work as well.

Partial

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When loading data from _source, partial fields can be used to use wildcards to control what part of the _source will be loaded based on include and exclude patterns. For example:

{
    "query" : {
        "match_all" : {}
    },
    "partial_fields" : {
        "partial1" : {
            "include" : "obj1.obj2.*",
        }
    }
}

And one that will also exclude obj1.obj3:

{
    "query" : {
        "match_all" : {}
    },
    "partial_fields" : {
        "partial1" : {
            "include" : "obj1.obj2.*",
            "exclude" : "obj1.obj3.*"
        }
    }
}

Both include and exclude support multiple patterns:

{
    "query" : {
        "match_all" : {}
    },
    "partial_fields" : {
        "partial1" : {
            "include" : ["obj1.obj2.*", "obj1.obj4.*"],
            "exclude" : "obj1.obj3.*"
        }
    }
}