diff --git a/cake/libs/model/datasources/dbo_source.php b/cake/libs/model/datasources/dbo_source.php
index 5de4db2ee..95929a56c 100644
--- a/cake/libs/model/datasources/dbo_source.php
+++ b/cake/libs/model/datasources/dbo_source.php
@@ -1378,6 +1378,7 @@ class DboSource extends DataSource {
 		} else {
 			$combined = array_combine($fields, $values);
 		}
+
 		$fields = implode(', ', $this->_prepareUpdateFields($model, $combined, empty($conditions)));
 
 		$alias = $joins = null;
@@ -1605,18 +1606,27 @@ class DboSource extends DataSource {
 	}
 /**
  * Creates a default set of conditions from the model if $conditions is null/empty.
+ * If conditions are supplied then they will be returned.  If a model doesn't exist and no conditions
+ * were provided either null or false will be returned based on what was input.
  *
  * @param object $model
- * @param mixed	 $conditions
+ * @param mixed $conditions Array of conditions, conditions string, null or false. If an array of conditions,
+ *   or string conditions those conditions will be returned.  With other values the model's existance will be checked.
+ *   If the model doesn't exist a null or false will be returned depending on the input value.
  * @param boolean $useAlias Use model aliases rather than table names when generating conditions
- * @return mixed
+ * @return mixed Either null, false, $conditions or an array of default conditions to use.
+ * @see DboSource::update()
+ * @see DboSource::conditions()
  */
 	function defaultConditions(&$model, $conditions, $useAlias = true) {
 		if (!empty($conditions)) {
 			return $conditions;
 		}
-		if (!$model->exists()) {
+		$exists = $model->exists();
+		if (!$exists && $conditions !== null) {
 			return false;
+		} elseif (!$exists) {
+			return null;
 		}
 		$alias = $model->alias;
 
@@ -1741,9 +1751,11 @@ class DboSource extends DataSource {
 		return array_unique($fields);
 	}
 /**
- * Creates a WHERE clause by parsing given conditions data.
+ * Creates a WHERE clause by parsing given conditions data.  If an array or string
+ * conditions are provided those conditions will be parsed and quoted.  If a boolean
+ * is given it will be integer cast as condition.  Null will return 1 = 1.
  *
- * @param mixed $conditions Array or string of conditions
+ * @param mixed $conditions Array or string of conditions, or any value.
  * @param boolean $quoteValues If true, values should be quoted
  * @param boolean $where If true, "WHERE " will be prepended to the return value
  * @param Model $model A reference to the Model instance making the query
@@ -1764,8 +1776,11 @@ class DboSource extends DataSource {
 			}
 			return $clause . implode(' AND ', $out);
 		}
+		if ($conditions === false || $conditions === true) {
+			return $clause . (int)$conditions . ' = 1';
+		}
 
-		if (empty($conditions) || trim($conditions) == '' || $conditions === true) {
+		if (empty($conditions) || trim($conditions) == '') {
 			return $clause . '1 = 1';
 		}
 		$clauses = '/^WHERE\\x20|^GROUP\\x20BY\\x20|^HAVING\\x20|^ORDER\\x20BY\\x20/i';
diff --git a/cake/tests/cases/libs/model/datasources/dbo_source.test.php b/cake/tests/cases/libs/model/datasources/dbo_source.test.php
index 321574ee6..7fe1a5a21 100644
--- a/cake/tests/cases/libs/model/datasources/dbo_source.test.php
+++ b/cake/tests/cases/libs/model/datasources/dbo_source.test.php
@@ -2096,6 +2096,30 @@ class DboSourceTest extends CakeTestCase {
 		$expected = array('DISTINCT `Vendor`.`id`', '`Vendor`.`name`');
 		$this->assertEqual($result, $expected);
 	}
+/**
+ * test that booleans and null make logical condition strings.
+ *
+ * @return void
+ */
+	function testBooleanNullConditionsParsing() {
+		$result = $this->testDb->conditions(true);
+		$this->assertEqual($result, ' WHERE 1 = 1', 'true conditions failed %s');
+
+		$result = $this->testDb->conditions(false);
+		$this->assertEqual($result, ' WHERE 0 = 1', 'false conditions failed %s');
+
+		$result = $this->testDb->conditions(null);
+		$this->assertEqual($result, ' WHERE 1 = 1', 'null conditions failed %s');
+
+		$result = $this->testDb->conditions(array());
+		$this->assertEqual($result, ' WHERE 1 = 1', 'array() conditions failed %s');
+
+		$result = $this->testDb->conditions('');
+		$this->assertEqual($result, ' WHERE 1 = 1', '"" conditions failed %s');
+
+		$result = $this->testDb->conditions(' ', '"  " conditions failed %s');
+		$this->assertEqual($result, ' WHERE 1 = 1');
+	}
 /**
  * testStringConditionsParsing method
  *
@@ -3093,6 +3117,7 @@ class DboSourceTest extends CakeTestCase {
 		$result = $this->testDb->renderStatement('delete', array('fields' => 'value=2', 'table' => 'table', 'conditions' => 'WHERE 1=1', 'alias' => 'alias', 'joins' => ''));
 		$this->assertPattern('/^\s*DELETE\s+alias\s+FROM\s+table\s+AS\s+alias\s+WHERE\s+1=1\s*$/', $result);
 	}
+
 /**
  * testStatements method
  *