.

rapids/forms.py

@@ -70,6 +70,8 @@ class RapidCreationDefaultForm(ModelForm):
 
 
 class RapidForm(ModelForm):
+
+    exams = ModelMultipleChoiceField(required=False, queryset=Exam.objects.all())
     class Media:
         # Django also includes a few javascript files necessary
         # for the operation of this form element. You need to
@@ -106,6 +108,39 @@ class RapidForm(ModelForm):
             choices=Rapid.LATERALITY_CHOICES, required=True, widget=RadioSelect()
         )
 
+        if kwargs.get("instance"):
+            # We get the 'initial' keyword argument or initialize it
+            # as a dict if it didn't exist.
+            initial = kwargs.setdefault("initial", {})
+            # The widget for a ModelMultipleChoiceField expects
+            # a list of primary key for the selected data.
+            initial["exams"] = [t.pk for t in kwargs["instance"].exams.all()]
+
+        ModelForm.__init__(self, *args, **kwargs)
+
+    def save(self, commit=True):
+        # Get the unsaved Pizza instance
+        instance = ModelForm.save(self, False)
+
+        # Prepare a 'save_m2m' method for the form,
+        old_save_m2m = self.save_m2m
+
+        def save_m2m():
+            old_save_m2m()
+            # This is where we actually link the pizza with toppings
+            instance.exams.clear()
+            for exam in self.cleaned_data["exams"]:
+                instance.exams.add(exam)
+
+        self.save_m2m = save_m2m
+
+        # Do we need to save all changes now?
+        # if commit:
+        instance.save()
+        self.save_m2m()
+
+        return instance
+
     class Meta:
         model = Rapid
         # fields = ['due_back']