app/assets/javascripts/trestle/components/_form.js in trestle-0.8.6 vs app/assets/javascripts/trestle/components/_form.js in trestle-0.8.7

@@ -8,18 +8,39 @@
 Trestle.init(function(e, root) {
   var form = $(root).find('form[data-behavior="trestle-form"]');
 
   form
     .on('ajax:complete', function(e, xhr, status) {
-      // Find the parent context and replace content
-      var context = $(this).closest('[data-context]');
-      context.html(xhr.responseText);
+      var contentType = xhr.getResponseHeader("Content-Type").split(";")[0];
 
-      // Initialize replaced elements within the context
-      $(Trestle).trigger('init', context);
+      if (contentType == "text/html") {
+        if (/<html/i.test(xhr.responseText)) {
+          // Response is a full HTML page, likely an error page. Render within an iframe.
 
-      // Focus the correct tab
-      Trestle.focusActiveTab();
+          var context = $(this).closest('[data-context]');
+          var iframe = $("<iframe>").addClass('error-iframe').get(0);
+          context.html(iframe);
+
+          iframe.contentWindow.document.documentElement.innerHTML = xhr.responseText;
+        } else {
+          // Find the parent context and replace content
+          var context = $(this).closest('[data-context]');
+          context.html(xhr.responseText);
+
+          // Initialize replaced elements within the context
+          $(Trestle).trigger('init', context);
+
+          // Focus the correct tab
+          Trestle.focusActiveTab();
+        }
+      } else {
+        // Assume an error response
+        var title = xhr.status + " (" + xhr.statusText + ")";
+        Trestle.Dialog.showError(title, xhr.responseText);
+
+        // Reset submit button
+        form.find(':submit').prop('disabled', false).removeClass('loading');
+      }
     })
     .on('ajax:success', function(e, data, status, xhr) {
       var context = $(this).closest('[data-context]');
       var location = xhr.getResponseHeader("X-Trestle-Location");