Disable flask-admin unique validator

Trying to insert an invalid IP or network address raises an exception.
This is due to the unique validator from flask-admin that queries the
database.

The unique validator is automatically added for columns with
unique=True. The only way to disable it is to monkey patch the Unique
class.
This allows the field validator to catch invalid format.

IntegrityError are already catched anyway.

app/admin/views.py

@@ -17,6 +17,15 @@ from .validators import IPNetwork
 from ..models import ICS_ID_RE
 
 
+# Monkey patch flask-admin Unique validator to disable it
+# Flask-admin automatically adds an unique validator that queries
+# the database. For some fields like INET and MACADDR, if the value
+# is invalid the database raises an exception. It's nicer to let the
+# field validator catches the incorrect format.
+# It's also better to let the database catch unicity error anyway.
+sqla.form.Unique.__call__ = lambda x, y, z: None
+
+
 # Add custom model converter for CIText type
 # See https://github.com/flask-admin/flask-admin/issues/1196
 class AppAdminModelConverter(sqla.form.AdminModelConverter):