Re-work #164 so getTotalAmount works in all cases.

Author: mattwire

Metadata/js/omnipay_PaypalRest.js

@@ -6,19 +6,18 @@
   function renderPaypal() {
     paypal.Buttons({
 
-
         onInit: function(data, actions) {
           // Set up the buttons.
           if (form.valid()) {
-            actions.enable()
+            actions.enable();
           }
           else {
             actions.disable();
           }
 
           form.on('blur keyup change', 'input', function (event) {
             if (form.valid()) {
-              actions.enable()
+              actions.enable();
             }
             else {
               actions.disable();
@@ -28,23 +27,41 @@
 
         createBillingAgreement: function (data, actions) {
 
+          // CRM.payment.getTotalAmount is implemented by webform_civicrm and mjwshared. The plan is to
+          //   add CRM.payment.getTotalAmount() into CiviCRM core. This code allows it to work under any of
+          //   these circumstances as well as if CRM.payment does not exist.
+          var totalAmount = 0.0;
+          if ((typeof CRM.payment !== 'undefined') && (CRM.payment.hasOwnProperty('getTotalAmount'))) {
+            totalAmount = CRM.payment.getTotalAmount();
+          }
+
+          if (typeof calculateTotalFee == 'function') {
+            // This is ONLY triggered in the following circumstances on a CiviCRM contribution page:
+            // - With a priceset that allows a 0 amount to be selected.
+            // - When we are the ONLY payment processor configured on the page.
+            totalAmount = parseFloat(calculateTotalFee());
+          }
+          else if (document.getElementById('total_amount')) {
+            // The input#total_amount field exists on backend contribution forms
+            totalAmount = parseFloat(document.getElementById('total_amount').value);
+          }
+
           var frequencyInterval = $('#frequency_interval').val() || 1;
           var frequencyUnit = $('#frequency_unit').val() ? $('#frequency_interval').val() : CRM.vars.omnipay.frequency_unit;
-          var paymentAmount = calculateTotalFee();
           var isRecur = $('#is_recur').is(":checked");
           var recurText = isRecur ? ' recurring' : '';
 
           return new Promise(function (resolve, reject) {
             CRM.api3('PaymentProcessor', 'preapprove', {
                 'payment_processor_id': CRM.vars.omnipay.paymentProcessorId,
-                'amount': paymentAmount,
+                'amount': totalAmount,
                 'currencyID' : CRM.vars.omnipay.currency,
                 'qf_key': qfKey,
                 'is_recur' : isRecur,
                 'installments' : $('#installments').val(),
                 'frequency_unit' : frequencyUnit,
                 'frequency_interval' : frequencyInterval,
-                'description' : CRM.vars.omnipay.title + ' ' + CRM.formatMoney(paymentAmount) + recurText,
+                'description' : CRM.vars.omnipay.title + ' ' + CRM.formatMoney(totalAmount) + recurText,
               }
             ).then(function (result) {
                 if (result['is_error'] === 1) {