diff --git a/edtf/fields.py b/edtf/fields.py
index b38873b..525fef6 100644
--- a/edtf/fields.py
+++ b/edtf/fields.py
@@ -125,8 +125,8 @@ def update_values(self, instance, *args, **kwargs):
 
         # Get existing value to determine if update is needed
         existing_value = getattr(instance, self.attname, None)
-        direct_input = getattr(instance, self.direct_input_field, None)
-        natural_text = getattr(instance, self.natural_text_field, None)
+        direct_input = getattr(instance, self.direct_input_field, "")
+        natural_text = getattr(instance, self.natural_text_field, "")
 
         # if direct_input is provided and is different from the existing value, update the EDTF field
         if direct_input and (
@@ -138,7 +138,7 @@ def update_values(self, instance, *args, **kwargs):
             # TODO pyparsing.ParseExceptions are very noisy and dumps the whole grammar (see https://github.com/ixc/python-edtf/issues/46)
 
             # set the natural_text (display) field to the direct_input if it is not provided
-            if natural_text is None:
+            if natural_text == "":
                 setattr(instance, self.natural_text_field, direct_input)
 
         elif natural_text:
diff --git a/edtf_django_tests/edtf_integration/migrations/0001_initial.py b/edtf_django_tests/edtf_integration/migrations/0001_initial.py
index 286a9de..0311290 100644
--- a/edtf_django_tests/edtf_integration/migrations/0001_initial.py
+++ b/edtf_django_tests/edtf_integration/migrations/0001_initial.py
@@ -28,7 +28,7 @@ class Migration(migrations.Migration):
                         blank=True,
                         help_text="Enter the date in natural language format (e.g., 'Approximately June 2004').",
                         max_length=255,
-                        null=True,
+                        null=False,
                         verbose_name="Date of creation (display)",
                     ),
                 ),
@@ -38,7 +38,7 @@ class Migration(migrations.Migration):
                         blank=True,
                         help_text="Enter the date in EDTF format (e.g., '2004-06~').",
                         max_length=255,
-                        null=True,
+                        null=False,
                         verbose_name="Date of creation (EDTF format)",
                     ),
                 ),
diff --git a/edtf_django_tests/edtf_integration/models.py b/edtf_django_tests/edtf_integration/models.py
index f5dbcc0..5120889 100644
--- a/edtf_django_tests/edtf_integration/models.py
+++ b/edtf_django_tests/edtf_integration/models.py
@@ -7,7 +7,7 @@ class TestEvent(models.Model):
     date_display = models.CharField(
         "Date of creation (display)",
         blank=True,
-        null=True,
+        null=False,
         max_length=255,
         help_text="Enter the date in natural language format (e.g., 'Approximately June 2004').",
     )
@@ -16,7 +16,7 @@ class TestEvent(models.Model):
         "Date of creation (EDTF format)",
         max_length=255,
         blank=True,
-        null=True,
+        null=False,
         help_text="Enter the date in EDTF format (e.g., '2004-06~').",
     )