Remove null=True de TextField

compilacao/migrations/0045_auto_20160404_1411.py

@@ -0,0 +1,21 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.9 on 2016-04-04 17:11
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('compilacao', '0044_auto_20160307_0918'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='textoarticulado',
+            name='observacao',
+            field=models.TextField(blank=True, default='', verbose_name='Observação'),
+            preserve_default=False,
+        ),
+    ]

compilacao/models.py

@@ -90,8 +90,7 @@ PARTICIPACAO_SOCIAL_CHOICES = [
 class TextoArticulado(TimestampedMixin):
     data = models.DateField(blank=True, null=True, verbose_name=_('Data'))
     ementa = models.TextField(verbose_name=_('Ementa'))
-    observacao = models.TextField(
-        blank=True, null=True, verbose_name=_('Observação'))
+    observacao = models.TextField(blank=True, verbose_name=_('Observação'))
     numero = models.PositiveIntegerField(verbose_name=_('Número'))
     ano = models.PositiveSmallIntegerField(verbose_name=_('Ano'))
     tipo_ta = models.ForeignKey(