[[custom-all]] === Custom _all Fields

In <>, we explained that the special _all field indexes the values from all other fields as one big string.((("_all field", sortas="all field")))((("multifield search", "custom _all fields"))) Having all fields indexed into one field is not terribly flexible, though. It would be nice to have one custom _all field for the person's name, and another custom _all field for the address.

Elasticsearch provides us with this functionality via the copy_to parameter in a field ((("copy_to parameter")))((("mapping (types)", "copy_to parameter")))mapping:

[source,js]

PUT /my_index { "mappings": { "person": { "properties": { "first_name": { "type": "string", "copy_to": "full_name" <1> }, "last_name": { "type": "string", "copy_to": "full_name" <1> }, "full_name": { "type": "string" } } } }

}

// SENSE: 110_Multi_Field_Search/45_Custom_all.json

<1> The values in the first_name and last_name fields are also copied to the full_name field.

With this mapping in place, we can query the first_name field for first names, the last_name field for last name, or the full_name field for first and last names.

NOTE: Mappings of the first_name and last_name fields have no bearing on how the full_name field is indexed. The full_name field copies the string values from the other two fields, then indexes them according to the mapping of the full_name field only.