fix: Fix persisting data to strings for the JSONField after a Django …

…1.9 change.

annoying/fields.py

@@ -110,6 +110,9 @@ class Page(models.Model):
     """
 
     def to_python(self, value):
+        """
+        Convert a string from the database to a Python value.
+        """
         if value == "":
             return None
 
@@ -122,6 +125,12 @@ def to_python(self, value):
             pass
         return value
 
+    def get_prep_value(self, value):
+        """
+        Convert the value to a string so it can be stored in the database.
+        """
+        return self.get_db_prep_save(value)
+
     def from_db_value(self, value, *args, **kwargs):
         return self.to_python(value)