[discrete]
[[esql-to_integer]]
=== `TO_INTEGER`
Converts an input value to an integer  value.

The input can be a single- or multi-valued field or an expression. The input
type must be of a boolean, date, string or numeric type.

Example:

[source.merge.styled,esql]
----
include::{esql-specs}/ints.csv-spec[tag=to_int-long]
----
[%header.monospaced.styled,format=dsv,separator=|]
|===
include::{esql-specs}/ints.csv-spec[tag=to_int-long-result]
|===

Note that in this example, the last value of the multi-valued field cannot
be converted as an integer. When this happens, the result is a *null* value.
In this case a _Warning_ header is added to the response. The header will
provide information on the source of the failure:

`"Line 1:61: evaluation of [TO_INTEGER(long)] failed, treating result as null. Only first 20 failures recorded."`

A following header will contain the failure reason and the offending value:

`"org.elasticsearch.xpack.ql.QlIllegalArgumentException: [501379200000] out of [integer] range"`


If the input parameter is of a date type, its value will be interpreted as
milliseconds since the https://en.wikipedia.org/wiki/Unix_time[Unix epoch],
converted to integer.

Boolean *true* will be converted to integer *1*, *false* to *0*.

Alias: TO_INT
