improve professor messages adding classroom

courses/migrations/0014_professormessage_classrooms.py

+# Generated by Django 2.2.14 on 2020-08-15 02:26
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('courses', '0013_auto_20200729_1612'),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name='professormessage',
+            name='classrooms',
+            field=models.ManyToManyField(blank=True, related_name='messages', to='courses.Classroom', verbose_name='Classrooms'),
+        ),
+    ]

courses/migrations/0015_auto_20200818_0320.py

+# Generated by Django 2.2.14 on 2020-08-18 06:20
+
+from django.db import migrations, models
+import django.db.models.deletion
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('courses', '0014_professormessage_classrooms'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='professormessage',
+            name='course',
+            field=models.ForeignKey(blank=True, null=True, on_delete=django.db.models.deletion.CASCADE, to='courses.Course', verbose_name='Course'),
+        ),
+    ]

courses/models.py

@@ -664,6 +664,7 @@ class ProfessorMessage(models.Model):
         models.CASCADE,
         verbose_name=_('Course'),
         null=True,
+        blank=True,
     )
     groups = models.ManyToManyField(
         Group,
@@ -678,6 +679,12 @@ class ProfessorMessage(models.Model):
         related_name='message_courses',
         blank=True,
     )
+    classrooms = models.ManyToManyField(
+        'Classroom',
+        verbose_name=_('Classrooms'),
+        related_name='messages',
+        blank=True,
+    )
 
     def __str__(self):
         return self.professor.name + " - " + self.subject + " - " + str(self.date)