Add the ability to make ajax calls on the input type of capa problems.

common/lib/capa/capa/capa_problem.py

@@ -146,6 +146,9 @@ class LoncapaProblem(object):
         if not self.student_answers:  # True when student_answers is an empty dict
             self.set_initial_display()
 
+        self.extracted_tree = self._extract_html(self.tree)
+
+
     def do_reset(self):
         '''
         Reset internal state to unfinished, with no answers
@@ -324,7 +327,21 @@ class LoncapaProblem(object):
         '''
         Main method called externally to get the HTML to be rendered for this capa Problem.
         '''
-        return contextualize_text(etree.tostring(self._extract_html(self.tree)), self.context)
+        html = contextualize_text(etree.tostring(self.extracted_tree), self.context)
+        return html
+
+
+    def handle_input_ajax(self, get):
+        '''
+        This passes any specialized input ajax onto the input class
+
+        It also parses out the dispatch from the get so that it can be passed onto the input type nicely
+        '''
+        if self.input:
+            dispatch = get['dispatch']
+            return self.input.handle_ajax(dispatch, get)
+        return {}
+
 
     # ======= Private Methods Below ========
 
@@ -458,6 +475,8 @@ class LoncapaProblem(object):
             finally:
                 sys.path = original_path
 
+
+
     def _extract_html(self, problemtree):  # private
         '''
         Main (private) function which converts Problem XML tree to HTML.
@@ -468,6 +487,7 @@ class LoncapaProblem(object):
 
         Used by get_html.
         '''
+
         if (problemtree.tag == 'script' and problemtree.get('type')
             and 'javascript' in problemtree.get('type')):
             # leave javascript intact.
@@ -505,8 +525,9 @@ class LoncapaProblem(object):
                                 'hintmode': hintmode, }}
 
             input_type_cls = inputtypes.registry.get_class_for_tag(problemtree.tag)
-            the_input = input_type_cls(self.system, problemtree, state)
-            return the_input.get_html()
+            # save the input type so that we can make ajax calls on it if we need to
+            self.input = input_type_cls(self.system, problemtree, state)
+            return self.input.get_html()
 
         # let each Response render itself
         if problemtree in self.responders:

common/lib/capa/capa/inputtypes.py

@@ -215,6 +215,18 @@ class InputTypeBase(object):
         """
         pass
 
+    def handle_ajax(self, dispatch, get):
+        """
+        InputTypes that need to handle specialized AJAX should override this.
+
+        Input:
+            dispatch: a string that can be used to determine how to handle the data passed in
+            get: a dictionary containing the data that was sent with the ajax call
+
+        Output:
+            a dictionary object that will then get sent back to the Javascript
+        """
+        pass
 
     def _get_render_context(self):
         """

common/lib/xmodule/xmodule/capa_module.py

@@ -412,6 +412,7 @@ class CapaModule(XModule):
                    'weight': self.descriptor.weight,
                    }
 
+
         context = {'problem': content,
                    'id': self.id,
                    'check_button': check_button,
@@ -449,6 +450,7 @@ class CapaModule(XModule):
             'problem_save': self.save_problem,
             'problem_show': self.get_answer,
             'score_update': self.update_score,
+            'input_ajax': self.lcp.handle_input_ajax
             }
 
         if dispatch not in handlers:

common/lib/xmodule/xmodule/js/src/capa/display.coffee

@@ -76,6 +76,14 @@ class @Problem
         # TODO: Some logic to dynamically adjust polling rate based on queuelen
         window.queuePollerID = window.setTimeout(@poll, 1000)
 
+
+  # Use this if you want to make an ajax call on the input type object 
+  # static method so you don't have to instantiate a Problem in order to use it
+  @inputAjax: (url, dispatch, data, callback) ->
+    data['dispatch'] = dispatch
+    $.postWithPrefix "#{url}/input_ajax", data, callback
+    
+
   render: (content) ->
     if content
       @el.html(content)