Feature/empty value exp

js/calculation-fields.js

@@ -39,16 +39,24 @@
         const deepFields = JSON.parse(fieldElement.dataset.evaluateDeepFields || "{}");
         const fieldEvaluateDecimals = fieldElement.dataset.evaluateDecimals || null;
         const buildExpression = (exp, field) => {
-          const currentElement = document.querySelector(`input[name="${field}"], select[name="${field}"]`);
+          const [fieldName, defaultValue] = field.split('|');
+          const currentElement = document.querySelector(`input[name="${fieldName}"], select[name="${fieldName}"]`);
           let currentFieldValue;
-          if (currentElement === null && deepFields[field] !== undefined) {
-            currentFieldValue = deepFields[field];
+          if (currentElement === null && deepFields[fieldName] !== undefined) {
+            currentFieldValue = deepFields[fieldName];
           }
           else {
             currentFieldValue = currentElement.value;
+            if (currentFieldValue === "" && defaultValue !== undefined) {
+              currentFieldValue = defaultValue
+            }
+          }
+          let fieldExp = fieldName;
+          if (defaultValue !== undefined) {
+            fieldExp += `|${defaultValue}`;
           }
           if (currentFieldValue !== '') {
-            return exp.replaceAll(`:${field}`, currentFieldValue);
+            return exp.replaceAll(`:${fieldExp}`, currentFieldValue);
           }
           return exp;
         }
@@ -57,7 +65,6 @@
           // If the value was clear. Rollback the element to the initial state.
           if (e.target.value === "" && previousValue[e.target.name] !== undefined && previousValue[e.target.name] !== "") {
             updateResult(fieldElement, "");
-            return;
           }
 
           const convertedExpression = fields.reduce(buildExpression, expression);
@@ -75,7 +82,8 @@
         if (formContext !== '') {
           selectorFormContext = `form#${formContext} `;
         }
-        fields.forEach(name => {
+        fields.forEach(fieldExp => {
+          const [name] = fieldExp.split('|');
           const elementSelector = `${selectorFormContext}input[name="${name}"], select[name="${name}"]`;
           const element = document.querySelector(elementSelector);
           if (element) {

modules/webform_calculation_fields/src/Plugin/WebformElement/WebformCalculationNumber.php

@@ -2,6 +2,7 @@
 
 namespace Drupal\webform_calculation_fields\Plugin\WebformElement;
 
+use Drupal\calculation_fields\Element\FormCalculationElement;
 use Drupal\Core\Form\FormStateInterface;
 use Drupal\webform\Plugin\WebformElement\Number;
 
@@ -41,13 +42,53 @@ class WebformCalculationNumber extends Number {
       '#weight' => 1,
     ];
 
+    $description = $this->t('e.g.:
+    :webform_element_key_1 + :webform_element_key_2 - (:webform_element_key_1 * :webform_element_key_3).
+    For non required field you must provide a default value to be used on the expression until the field be populated, just adding |defaultValue, like :my_field_name|0');
+
     $form['element']['evaluation_fields'] = [
       '#type' => 'textarea',
       '#title' => $this->t('Math Expression'),
-      '#description' => $this->t('e.g.: :webform_element_key_1 + :webform_element_key_2 - (:webform_element_key_1 * :webform_element_key_3)'),
+      '#description' => $description,
       '#weight' => 2,
     ];
     return $form;
   }
 
+  /**
+   * {@inheritDoc}
+   */
+  public function validateConfigurationForm(array &$form, FormStateInterface $form_state) {
+    $expression = $form_state->getValue('evaluation_fields');
+    $fields = FormCalculationElement::evaluateFields($expression);
+    $currentWebform = $this->getWebform();
+    $invalidFields = [];
+    foreach ($fields as $field) {
+      [$fieldName, $defaultValue] = explode('|', $field);
+      $element = $currentWebform->getElement($fieldName);
+      if (!$element) {
+        $invalidFields[] = $fieldName;
+      }
+      elseif (!$element['#required'] && is_null($defaultValue)) {
+        $form_state
+          ->setErrorByName(
+            'evaluation_fields',
+            $this->t('The field @field are not required and are present on the expression, you must provide a default value, eg: @field|0 or @field|1', [
+              '@field' => $fieldName,
+            ])
+          );
+      }
+    }
+    if (!empty($invalidFields)) {
+      $form_state
+        ->setErrorByName(
+          'evaluation_fields',
+          $this->t('The following field(s) (@fields) does not exists on the webform. Please check your expression!',
+            ['@fields' => implode(', ', $invalidFields)]
+          )
+        );
+    }
+    return parent::validateConfigurationForm($form, $form_state);
+  }
+
 }

src/Element/FormCalculationElement.php

@@ -121,10 +121,14 @@ class FormCalculationElement extends Number {
     $fields = static::evaluateFields($evaluation);
     $collectedValues = [];
     foreach ($fields as $field) {
-      $value = $form_state->getValue($field);
+      [$fieldName, $defaultValue] = explode('|', $field);
+      $value = $form_state->getValue($fieldName);
       if (!empty($value)) {
         $collectedValues[$field] = $value;
       }
+      elseif (!is_null($defaultValue)) {
+        $collectedValues[$field] = $defaultValue;
+      }
     }
     if (count($collectedValues) !== count(array_unique($fields))) {
       return NULL;
@@ -152,7 +156,7 @@ class FormCalculationElement extends Number {
     foreach ($expressionFields as $field) {
       $items = explode(' ', $field);
       $items = array_map(function ($item) {
-        return preg_replace("/[^a-zA-Z0-9_]/", "", $item);
+        return preg_replace("/[^a-zA-Z0-9_|]/", "", $item);
       }, $items);
       $filteredItems = array_filter($items, function ($item) {
         return !is_numeric($item) && !empty($item);