added new find methods

twistar/dbobject.py

@@ -8,7 +8,7 @@
 from twistar.registry import Registry
 from twistar.relationships import Relationship
 from twistar.exceptions import InvalidRelationshipError, DBObjectSaveError, ReferenceNotSavedError
-from twistar.utils import createInstances, deferredDict
+from twistar.utils import createInstances, deferredDict, dictToWhere
 from twistar.validation import Validator, Errors
 
 from BermiInflector.Inflector import Inflector
@@ -364,6 +364,34 @@ class name.
         return klass.TABLENAME
 
 
+    @classmethod
+    def findOrCreate(klass, **attrs):
+        """
+        Find all instances of a given class based on the attributes given (just like C{findBy}).
+
+        If a match isn't found, create a new instance and return that.
+        """
+        def handle(result):
+            if len(result) == 0:
+                return klass(**attrs).save()
+            return result[0]
+        return klass.findBy(**attrs).addCallback(handle)
+
+
+    @classmethod
+    def findBy(klass, **attrs):
+        """
+        Find all instances of the given class based on an exact match of attributes.
+
+        For instance:
+        C{User.find(first_name='Bob', last_name='Smith')}
+
+        Will return all matches.
+        """
+        where = dictToWhere(attrs)
+        return klass.find(where = where)
+
+
     @classmethod
     def find(klass, id=None, where=None, group=None, limit=None, orderby=None):
         """

twistar/tests/test_dbobject.py

@@ -22,6 +22,36 @@ def tearDown(self):
         yield tearDownDB(self)        
 
 
+    @inlineCallbacks
+    def test_findBy(self):
+        r = yield User.findBy(first_name="Non", last_name="Existant")
+        self.assertEqual(r, [])
+
+        r = yield User.findBy(first_name="First", last_name="Last", age=11)
+        self.assertEqual(r, [])
+
+        r = yield User.findBy(first_name="First", last_name="Last", age=10)
+        self.assertEqual(r[0], self.user)
+
+        r = yield User.findBy(first_name="First", last_name="Last")
+        self.assertEqual(r[0], self.user)
+
+        u = yield User(first_name="Bob").save()
+        r = yield User.findBy()
+        self.assertEqual(len(r), 2)
+
+
+    @inlineCallbacks
+    def test_findOrCreate(self):
+        # make sure we didn't create a new user
+        r = yield User.findOrCreate(first_name="First")
+        self.assertEqual(r.id, self.user.id)
+
+        # make sure we do create a new user
+        r = yield User.findOrCreate(first_name="First", last_name="Non")
+        self.assertTrue(r.id != self.user.id)
+
+
     @inlineCallbacks
     def test_creation(self):
         # test creating blank object 

twistar/utils.py

@@ -27,7 +27,23 @@ def createInstances(props, klass):
 
     return defer.succeed(None)
 
-
+
+def dictToWhere(attrs, joiner="AND"):
+    """
+    Convert a dictionary of attribute: value to a where statement.
+
+    For instance, dictToWhere({'one': 'two', 'three': 'four'}) returns:
+    ['(one = ?) AND (three = ?)', 'two', 'four']
+
+    @return: Expression above if len(attrs) > 0, None otherwise
+    """
+    if len(attrs) == 0:
+        return None
+
+    wheres = map(lambda name: "(%s = ?)" % name, attrs.keys())
+    return [(" %s " % joiner).join(wheres)] + attrs.values()
+
+
 def joinWheres(wone, wtwo, joiner="AND"):
     """
     Take two wheres (of the same format as the C{where} parameter in the function