First release feature complete.

Author: Matthew Mirus

gravityforms-regex-validation.php

@@ -0,0 +1,102 @@
+<?php
+/*
+Plugin Name: Gravity Forms Regular Expression Validation
+Plugin URI: https://github.com/mmirus/gravityforms-regex-validation
+Description: Add regular expression validation option to Gravity Forms single text input
+Author: Matt Mirus
+Author URI: https://github.com/mmirus
+Version: 1.0
+GitHub Plugin URI: https://github.com/mmirus/gravityforms-regex-validation
+*/
+
+namespace GF_RegEx;
+
+class GF_RegEx {
+  function __construct() {
+    // add field
+    add_action('gform_field_advanced_settings', array($this, 'settings_fields'), 10, 2);
+    
+    // add script
+    add_action('gform_editor_js', array($this, 'editor_script'));
+    
+    // add validation
+    add_filter('gform_field_validation', array($this, 'validate'), 10, 4);
+  }
+  
+  // add regex validation setting fields
+  public function settings_fields($position, $form_id) {
+    //create settings on position 375 (right after "enable password input")
+    if ( $position == 375 ) {
+      ?>
+      <li class="regex_setting field_setting">
+        <input type="checkbox" id="field_regex_validation" onclick="SetFieldProperty('regexValidation', this.checked); ToggleInputRegEx()" onkeypress="SetFieldProperty('regexValidation', this.checked); ToggleInputRegEx()" />
+        <label for="field_regex_validation" class="inline">
+          <?php _e("Use Regular Expression Validation", "gf_regex"); ?>
+        </label>
+        
+        <div id="field_regex_pattern_container" style="padding-top: 10px; display: block;">
+          <p>
+            <label for="field_regex_pattern" class="inline">RegEx Pattern:&nbsp;</label>
+            <input type="text" id="field_regex_pattern" onchange="SetFieldProperty('regexPattern', this.value)" class="fieldwidth-2" placeholder="">
+          </p>
+          <p>
+            <label for="field_regex_message" class="inline">Validation Message:&nbsp;</label>
+            <input type="text" id="field_regex_message" onchange="SetFieldProperty('regexMessage', this.value)" class="fieldwidth-2" placeholder="The value provided is not valid for this field.">
+          </p>
+        </div>
+      </li>
+      <?php
+    }
+  }
+  
+  // Action to inject supporting script to the form editor page
+  public function editor_script() {
+    ?>
+    <script type='text/javascript'>
+      // adding setting to fields of type "text"
+      fieldSettings.text += ", .regex_setting";
+
+      // binding to the load field settings event to initialize the checkbox
+      jQuery(document).bind("gform_load_field_settings", function(event, field, form) {
+        jQuery("#field_regex_validation").attr("checked", field["regexValidation"] == true);
+        jQuery("#field_regex_pattern").val(field["regexPattern"]);
+        jQuery("#field_regex_message").val(field["regexMessage"]);
+        
+        ToggleInputRegEx(true);
+      });
+      
+      // show / hide regex pattern input field
+      function ToggleInputRegEx(isInit){
+        var speed = isInit ? "" : "slow";
+        if(jQuery('#field_regex_validation').is(":checked")){
+          jQuery('#field_regex_pattern_container').show(speed);
+        }
+        else{
+          jQuery('#field_regex_pattern_container').hide(speed);
+        }
+      }
+    </script>
+    <?php
+  }
+
+  // validate submitted data against provided regex
+  public function validate($result, $value, $form, $field) {
+    // if validation has passed so far, and regex validation is enabled, and a pattern was provided, and a value was provided
+    if ($result['is_valid'] && $field['regexValidation'] && !empty($field['regexPattern']) && !empty($value)) {
+      $regex = '/' . $field['regexPattern'] . '/';
+      if (preg_match($regex, $value) !== 1) {
+        $result['is_valid'] = false;
+        
+        // use custom regex validation message if provided
+        $result['message'] = 'The value provided is not valid for this field.';
+        if (!empty($field['regexMessage'])) {
+          $result['message'] = $field['regexMessage'];
+        }
+      }
+    }
+    
+    return $result;
+  }
+}
+
+new GF_Regex();