adding warning message if more than one inputtypes in one question

cms/templates/js/xblock-validation-messages.underscore

 <%
 var summaryMessage = validation.get("summary");
 var aggregateMessageType = summaryMessage.type;
-var aggregateValidationClass = aggregateMessageType === "error"? "has-errors" : "has-warnings";
+var aggregateValidationClass = aggregateMessageType === "error" ? "has-errors" : "has-warnings";
 %>
     <div class="xblock-message validation <%= aggregateValidationClass %> <%= additionalClasses %>">
         <p class="<%= aggregateMessageType %>"><i class="icon fa <%= getIcon(aggregateMessageType) %>"></i>
         <%- summaryMessage.text %>
         <% if (summaryMessage.action_class) { %>
-            <a href="#" class="button action-button <%- summaryMessage.action_class %>">
+            <a href="<%= summaryMessage.action_link ? summaryMessage.action_link : '#' %>" class="button action-button <%- summaryMessage.action_class %>">
                 <span class="action-button-text"><%- summaryMessage.action_label %></span>
+                <% if (summaryMessage.action_class === 'external-link') { %>
+                  <i class="fa fa-external-link-square" aria-hidden="true"></i>
+                <% } %>
             </a>
         <% } else if (summaryMessage.action_runtime_event) {%>
             <a href="#" class="button action-button notification-action-button" data-notification-action="<%- summaryMessage.action_runtime_event %>">

common/lib/xmodule/xmodule/capa_module.py

@@ -8,6 +8,8 @@ from lxml import etree
 from pkg_resources import resource_string
 
 import dogstats_wrapper as dog_stats_api
+
+from xmodule.validation import StudioValidation, StudioValidationMessage
 from .capa_base import CapaMixin, CapaFields, ComplexEncoder
 from capa import responsetypes
 from .progress import Progress
@@ -128,6 +130,15 @@ class CapaModule(CapaMixin, XModule):
 
         return json.dumps(result, cls=ComplexEncoder)
 
+    def validate(self):
+        """
+        Message for either error or warning validation message/s.
+
+        Returns message and type. Priority given to error type message.
+        """
+        return self.descriptor.validate()
+
+
 
 class CapaDescriptor(CapaFields, RawDescriptor):
     """
@@ -256,6 +267,48 @@ class CapaDescriptor(CapaFields, RawDescriptor):
             )
         return False
 
+    def validate(self):
+        """
+        Validates the xml for correct question separation. There must be only one inputtype in every <question>.
+        This is the override of the general XBlock method.
+        """
+
+        validation = super(CapaDescriptor, self).validate()
+        validation = StudioValidation.copy(validation)
+
+        # validate xml to check questions are correctly separated
+        is_valid = self.validate_xml()
+
+        if not is_valid:
+            validation.set_summary(
+                StudioValidationMessage(
+                    StudioValidationMessage.WARNING,
+                    u'Incorrect problem format detected!',
+                    action_label=u"Please see docs.",
+                    action_class=u"external-link",
+                    action_link=u"http://docs.edx.org/"
+                )
+            )
+
+        return validation
+
+    def validate_xml(self):
+        input_tags = ['choiceresponse', 'optionresponse', 'multiplechoiceresponse', 'stringresponse',
+                      'numericalresponse', 'schematicresponse', 'imageresponse', 'formularesponse']
+
+        xmltree = etree.fromstring(self.data)
+        questions = xmltree.findall(".//question")
+
+        for question in questions:
+            for tag in input_tags:
+                tag_elements = question.findall(".//" + tag)
+                if len(tag_elements) > 1:
+                    print("more choices")
+                    return False
+
+        return True
+
+
     # Proxy to CapaModule for access to any of its attributes
     answer_available = module_attr('answer_available')
     check_button_name = module_attr('check_button_name')

common/lib/xmodule/xmodule/validation.py

@@ -15,12 +15,13 @@ class StudioValidationMessage(ValidationMessage):
 
     TYPES = [ValidationMessage.WARNING, ValidationMessage.ERROR, NOT_CONFIGURED]
 
-    def __init__(self, message_type, message_text, action_label=None, action_class=None, action_runtime_event=None):
+    def __init__(self, message_type, message_text, action_label=None, action_class=None, action_runtime_event=None,
+                 action_link=None):
         """
         Create a new message.
 
         Args:
-            message_type (str): The type associated with this message. Most be `WARNING` or `ERROR`.
+            message_type (str): The type associated with this message. Must be `WARNING` or `ERROR`.
             message_text (unicode): The textual message.
             action_label (unicode): Text to show on a "fix-up" action (optional). If present, either `action_class`
                 or `action_runtime_event` should be specified.
@@ -43,6 +44,10 @@ class StudioValidationMessage(ValidationMessage):
             if not isinstance(action_runtime_event, basestring):
                 raise TypeError("Action runtime event must be a string.")
             self.action_runtime_event = action_runtime_event
+        if action_link is not None:
+            if not isinstance(action_link, basestring):
+                raise TypeError("Action link must be a string.")
+            self.action_link = action_link
 
     def to_json(self):
         """
@@ -58,6 +63,8 @@ class StudioValidationMessage(ValidationMessage):
             serialized["action_class"] = self.action_class
         if hasattr(self, "action_runtime_event"):
             serialized["action_runtime_event"] = self.action_runtime_event
+        if hasattr(self, "action_link"):
+            serialized["action_link"] = self.action_link
         return serialized