update docs part 2

docs_src/models/docs006.py

@@ -0,0 +1,21 @@
+import databases
+import sqlalchemy
+
+import ormar
+
+database = databases.Database("sqlite:///db.sqlite")
+metadata = sqlalchemy.MetaData()
+
+
+class Course(ormar.Model):
+    class Meta:
+        database = database
+        metadata = metadata
+        # define your constraints in Meta class of the model
+        # it's a list that can contain multiple constraints
+        # hera a combination of name and column will have to be unique in db
+        constraints = [ormar.UniqueColumns('name', 'completed')]
+
+    id = ormar.Integer(primary_key=True)
+    name = ormar.String(max_length=100)
+    completed = ormar.Boolean(default=False)