Add sphinx based docs

docs/source/constraints.rst

@@ -0,0 +1,100 @@
+.. _unique_together: https://docs.djangoproject.com/en/2.2/ref/models/options/#unique-together
+
+Constraints
+===========
+
+All constraints are enforced by PostgreSQL. Constraints can be applied to all fields documented in :ref:`Fields <fields>`.
+
+.. warning::
+
+    Don't forget to run ``python manage.py makemigrations`` after modifying constraints.
+
+Required/optional
+-----------------
+
+
+* Default language required and all other languages optional:
+
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField()
+
+
+* All languages are optional and the field itself can be ``None``:
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(blank=True, null=True, required=False)
+
+* All languages are optional but the field itself cannot be ``None``:
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(blank=False, null=False, required=False)
+
+
+* Make specific languages required:
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(blank=False, null=False, required=['en', 'ro'])
+
+
+* Make all languages required:
+
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(blank=False, null=False, required=True)
+
+
+Uniqueness
+----------
+
+.. note::
+
+    Uniqueness is enforced by PostgreSQL by creating unique indexes on hstore keys. Keep this is mind when setting up unique constraints. If you already have a unique constraint in place, you do not have to add an additional index as uniqueness is enforced by creating an index.
+
+
+* Enforce uniqueness for one or more languages:
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(uniqueness=['en', 'ro'])
+
+
+* Enforce uniqueness for all languages:
+
+    .. code-block:: python
+
+        from localized_fields.util import get_language_codes
+
+        class MyModel(models.Model):
+            title = LocalizedField(uniqueness=get_language_codes())
+
+
+* Enforce uniqueness for one or more languages together:
+
+    .. code-block:: python
+
+        class MyModel(models.Model):
+            title = LocalizedField(uniqueness=[('en', 'ro')])
+
+    This is similar to Django's `unique_together`_.
+
+
+* Enforce uniqueness for all languages together:
+
+    .. code-block:: python
+
+        from localized_fields.util import get_language_codes
+
+        class MyModel(models.Model):
+            title = LocalizedField(uniqueness=[(*get_language_codes())])