feat: get_or_none method (#185)

.gitignore

@@ -61,3 +61,5 @@ target/
 # poetry
 poetry.lock
 
+# pytest
+.pytest_cache/

README.md

@@ -27,13 +27,13 @@ Install
 
 Install with `pip` for PostgreSQL:
 
-```
+```bash
 pip install --pre peewee-async; pip install aiopg
 ```
 
 or for MySQL:
 
-```
+```bash
 pip install --pre peewee-async; pip install aiomysql
 ```
 
@@ -57,7 +57,7 @@ database = peewee_async.PostgresqlDatabase(
     user='user',
     host='127.0.0.1',
     port='5432',
-    password='password'
+    password='password',
 )
 
 class TestModel(peewee.Model):
@@ -106,22 +106,25 @@ http://peewee-async.readthedocs.io
 
 Developing
 ----------
-Install dependencies using pip: 
-
-```pip install -e .[develop]```
-
-Or using [poetry](https://python-poetry.org/docs/): 
-
-```poetry install -E develop```
+Install dependencies using pip:
+```bash
+pip install -e .[develop]
+```
 
+Or using [poetry](https://python-poetry.org/docs/):
+```bash
+poetry install -E develop
+```
 
 Run databases:
-
-```docker-compose up -d```
+```bash
+docker-compose up -d
+```
 
 Run tests:
-
-```pytest tests -v -s```
+```bash
+pytest tests -v -s
+```
 
 Discuss
 -------

peewee_async.py

@@ -201,6 +201,13 @@ async def get_or_create(self, model_, defaults=None, **kwargs):
             data.update({k: v for k, v in kwargs.items() if '__' not in k})
             return (await self.create(model_, **data)), True
 
+    async def get_or_none(self, model_, *args, **kwargs):
+        """Try to get an object and return None if it doesn't exist."""
+        try:
+            return (await self.get(model_, *args, **kwargs))
+        except model_.DoesNotExist:
+            pass
+
     async def update(self, obj, only=None):
         """Update the object in the database. Optionally, update only
         the specified fields. For creating a new object use :meth:`.create()`

tests/test_common.py

@@ -0,0 +1,20 @@
+import uuid
+
+from tests.conftest import all_dbs
+from tests.models import TestModel
+
+
+@all_dbs
+async def test_get_or_none(manager):
+    """Test get_or_none manager function."""
+    text1 = "Test %s" % uuid.uuid4()
+    text2 = "Test %s" % uuid.uuid4()
+
+    obj1 = await manager.create(TestModel, text=text1)
+    obj2 = await manager.get_or_none(TestModel, text=text1)
+    obj3 = await manager.get_or_none(TestModel, text=text2)
+
+    assert obj1 == obj2
+    assert obj1 is not None
+    assert obj2 is not None
+    assert obj3 is None