Gravity form Custom Validation

<?php
add_filter(‘gform_validation_1’, ‘custom_validation’);
function custom_validation($validation_result){
$form = $validation_result[“form”];
foreach($form[‘fields’] as &$field){
if($_POST[‘input_1’] == “”){
// set the form validation to false
$validation_result[“is_valid”] = false;
if($field[“id”] == “1”){
$field[“failed_validation”] = true;
$field[“validation_message”] = “Please Enter Your Name.”;
}
}
if ($_POST[‘input_2’] == “”){
// set the form validation to false
$validation_result[“is_valid”] = false;
if($field[“id”] == “2”){
$field[“failed_validation”] = true;
$field[“validation_message”] = “Please Enter Your Email Address”;
}
}

if ($_POST[‘input_3’] == “”){
// set the form validation to false
$validation_result[“is_valid”] = false;
if($field[“id”] == “3”){
$field[“failed_validation”] = true;
$field[“validation_message”] = “Please Enter Your Phone Number”;
}
}

} // main
//Assign modified $form object back to the validation result
$validation_result[“form”] = $form;
return $validation_result;
}?>