---
name: "WebCommon.incomingExists"
section: "3kaya"
platform: "linux"
package: "kaya"
version: "0.4.4-6.2"
release: "Debian 8 (Jessie)"
platforms: ["linux"]
url: "https://new.carta.tech/WebCommon.incomingExists"
---

# WebCommon.incomingExists(3kaya)

Checks a key exists in user-supplied data

## NAME

WebCommon::incomingExists - Checks a key exists in user-supplied data

## SYNOPSIS

**Bool incomingExists(** *String key, DataSource ds* **)**

## ARGUMENTS

**key** The key to check

**ds** The source for user-supplied data

## DESCRIPTION

Returns **true**  if the key exists in the data source, and **false**  otherwise.

-

   // GET /example.cgi?a=1;b=3;b=5;z=;z;z\
    val = incomingExists("a",DataGet);\
    // val = true\
    val = incomingExists("b",DataGet);\
    // val = true\
    val = incomingExists("c",DataGet);\
    // val = false\
    val = incomingExists("z",DataGet);\
    // val = true

This is useful for avoiding Exceptions when using **WebCommon.incomingData (3kaya)** or **WebCommon.incomingValue (3kaya)** , or for checking if a checkbox has been selected.

## AUTHORS

Kaya standard library by Edwin Brady, Chris Morris and others (kaya@kayalang.org). For further information see http://kayalang.org/

## LICENSE

The Kaya standard library is free software; you can redistribute it and/or modify it under the terms of the GNU Lesser General Public License (version 2.1 or any later version) as published by the Free Software Foundation.

## RELATED

**WebCommon.DataSource (3kaya)**

**WebCommon.incomingData (3kaya)**

**WebCommon.incomingKeys (3kaya)**

**WebCommon.incomingValue (3kaya)**