Conditional Logic: Fuzzy Comparison for “is” Operator
This snippet adds fuzzy comparison for Gravity Forms’ conditional logic “is” operator. This allows you to match values that are similar but not identical (e.g. “África”, “Africa”, “Africaa”).
Instructions
See “Where do I put snippets?” in our documentation for installation instructions.
Code
Filename: gw-fuzzy-comparison.php
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<?php
/**
* Gravity Wiz // Gravity Forms // Conditional Logic: Fuzzy Comparison for "is" Operator
*
* This snippet adds fuzzy comparison for Gravity Forms' conditional logic "is" operator. This allows you to match values that are similar but not identical (e.g. "África", "Africa", "Africaa").
*/
class GW_Fuzzy_Match {
private $_args;
public function __construct( $args = array() ) {
// Set our default arguments, parse against the provided arguments, and store for use throughout the class
$this->_args = wp_parse_args( $args, array(
'form_id' => false,
'field_id' => false,
'threshold' => 1,
) );
// Do version check in the init to make sure if GF is going to be loaded, it is already loaded
add_action( 'init', array( $this, 'init' ) );
}
public function init() {
// Add hooks for PHP filtering
add_filter( 'gform_is_value_match', array( $this, 'apply_fuzzy_match' ), 10, 6 );
// Add hooks for JS script
add_filter( 'gform_pre_render', array( $this, 'load_form_script' ), 10, 2 );
add_action( 'gform_register_init_scripts', array( $this, 'add_init_script' ), 10, 2 );
}
public function apply_fuzzy_match( $is_match, $field_value, $target_value, $operation, $source_field, $rule ) {
if ( $rule['operator'] !== 'is' ) {
return $is_match;
}
return $this->fuzzy_match( $field_value, trim( $target_value ) );
}
public function fuzzy_match( $input, $target ) {
$normalized_input = $this->normalize_string( $input );
$normalized_target = $this->normalize_string( $target );
$distance = levenshtein( $normalized_input, $normalized_target );
return $distance <= $this->_args['threshold'];
}
public function normalize_string( $str ) {
$str = iconv( 'UTF-8', 'ASCII//TRANSLIT', $str );
return strtolower( preg_replace( '/[^a-zA-Z0-9]/', '', $str ) );
}
public function load_form_script( $form, $is_ajax_enabled ) {
if ( $this->is_applicable_form( $form ) && ! has_action( 'wp_footer', array( $this, 'output_script' ) ) ) {
add_action( 'wp_footer', array( $this, 'output_script' ) );
add_action( 'gform_preview_footer', array( $this, 'output_script' ) );
}
return $form;
}
public function output_script() {
?>
<script type="text/javascript">
( function( $ ) {
window.GW_Fuzzy_Match = function( args ) {
var self = this;
// Copy all args to current object: (list expected props)
for( var prop in args ) {
if( args.hasOwnProperty( prop ) ) {
self[ prop ] = args[ prop ];
}
}
self.isApplicableField = function(fieldId) {
if ( typeof fieldId !== 'number' ) {
fieldId = parseInt( fieldId );
}
if ( ! self.fieldId ) {
return true;
}
if ( typeof self.fieldId !== 'object' ) {
self.fieldId = [ self.fieldId ];
}
// Ensure fieldIds are all numbers
self.fieldId = self.fieldId.map( function( fieldId ) {
if ( typeof fieldId === 'string' ) {
fieldId = parseInt( fieldId );
}
return fieldId;
} );
return self.fieldId.indexOf( fieldId ) !== -1;
};
self.init = function() {
gform.addFilter('gform_is_value_match', function (isMatch, formId, rule) {
if ( rule.operator !== 'is' ) {
return isMatch;
}
var source = jQuery( '#input_' + formId + '_' + rule.fieldId );
if ( source ) {
return self.fuzzyMatch( source.val(), rule.value );
}
return isMatch;
});
};
self.normalizeString = function( str ) {
return str.normalize("NFD").replace( /[\u0300-\u036f]/g, "" ).toLowerCase();
};
self.levenshtein = function( a, b ) {
const an = a.length;
const bn = b.length;
if (an === 0) return bn;
if (bn === 0) return an;
const matrix = [];
for (let i = 0; i <= bn; i++) {
matrix[i] = [i];
}
for (let j = 0; j <= an; j++) {
matrix[0][j] = j;
}
for (let i = 1; i <= bn; i++) {
for (let j = 1; j <= an; j++) {
if (b.charAt(i - 1) === a.charAt(j - 1)) {
matrix[i][j] = matrix[i - 1][j - 1];
} else {
matrix[i][j] = Math.min(
matrix[i - 1][j - 1] + 1,
Math.min(
matrix[i][j - 1] + 1,
matrix[i - 1][j] + 1
)
);
}
}
}
return matrix[bn][an];
};
self.fuzzyMatch = function( input, target ) {
const normalizedInput = self.normalizeString( input );
const normalizedTarget = self.normalizeString( target );
const distance = self.levenshtein( normalizedInput, normalizedTarget );
return distance <= self.threshold;
};
self.init();
};
} )( jQuery );
</script>
<?php
}
public function add_init_script( $form ) {
if ( ! $this->is_applicable_form( $form ) ) {
return;
}
$args = array(
'formId' => $this->_args['form_id'],
'fieldId' => $this->_args['field_id'],
'threshold' => $this->_args['threshold'],
);
$script = 'new GW_Fuzzy_Match( ' . json_encode( $args ) . ' );';
$slug = implode( '_', array( strtolower( __CLASS__ ), $this->_args['form_id'], $this->_args['field_id'] ) );
GFFormDisplay::add_init_script( $form['id'], $slug, GFFormDisplay::ON_PAGE_RENDER, $script );
}
public function is_applicable_form( $form ) {
$form_id = isset( $form['id'] ) ? $form['id'] : $form;
return empty( $this->_args['form_id'] ) || (int) $form_id === (int) $this->_args['form_id'];
}
}
# Configuration
new GW_Fuzzy_Match( array(
'form_id' => 1, // Replace with your form ID.
'field_id' => 2, // Replace with your field ID for which conditional logic needs to be fuzzy.
'threshold' => 1, // Define the maximum number of allowed differences between two strings for them to be considered a match.
) );