null value support for dynamic finders (#1220)

* null value support for dynamic finders
#1182

* null value support for dynamic finders
#1182

* null value support for dynamic finders
#1182

Author: demon101

grails-datastore-gorm-tck/src/main/groovy/grails/gorm/tests/NullValueEqualSpec.groovy

@@ -0,0 +1,19 @@
+package grails.gorm.tests
+
+class NullValueEqualSpec extends GormDatastoreSpec {
+
+  void "test null value in equal and not equal"() {
+    when:
+    new TestEntity(name:"Fred", age: null).save(failOnError: true)
+    new TestEntity(name:"Bob", age: 11).save(failOnError: true)
+    new TestEntity(name:"Jack", age: null).save(flush:true, failOnError: true)
+
+    then:
+    TestEntity.countByAge(11) == 1
+    TestEntity.findAllByAge(null).size() == 2
+    TestEntity.countByAge(null) == 2
+
+    TestEntity.countByAgeNotEqual(11) == 2
+    TestEntity.countByAgeNotEqual(null) == 1
+  }
+}

grails-datastore-gorm-tck/src/main/groovy/grails/gorm/tests/TestEntity.groovy

@@ -16,12 +16,13 @@ class TestEntity implements Serializable {
 
     static mapping = {
         name index:true
-        age index:true, nullable:true
-        child index:true, nullable:true
+        age index:true
+        child index:true
     }
 
     static constraints = {
         name blank:false
         child nullable:true
+        age nullable:true
     }
 }

grails-datastore-gorm/src/main/groovy/org/grails/datastore/gorm/finders/DynamicFinder.java

@@ -765,11 +765,11 @@ private static String calcPropertyName(String queryParameter, String clause) {
      * @return the initialized expression
      */
     private MethodExpression getInitializedExpression(MethodExpression expression, Object[] arguments) {
-        if (expression instanceof Equal && arguments.length == 1 && arguments[0] == null) {
-            expression = new IsNull(expression.propertyName);
-        } else {
-            expression.setArguments(arguments);
-        }
+//        if (expression instanceof Equal && arguments.length == 1 && arguments[0] == null) { // logic moved directly to Equal.createCriterion
+//            expression = new IsNull(expression.propertyName);
+//        } else {
+        expression.setArguments(arguments);
+//        }
         return expression;
     }
 

grails-datastore-gorm/src/main/groovy/org/grails/datastore/gorm/finders/MethodExpression.java

@@ -422,7 +422,12 @@ public Equal(String propertyName) {
 
         @Override
         public Query.Criterion createCriterion() {
-            return Restrictions.eq(propertyName, arguments[0]);
+            Object argument = arguments[0];
+            if (argument != null) {
+                return Restrictions.eq(propertyName, argument);
+            } else {
+                return Restrictions.isNull(propertyName);
+            }
         }
 
     }
@@ -437,7 +442,12 @@ public NotEqual(String propertyName) {
 
         @Override
         public Query.Criterion createCriterion() {
-            return Restrictions.ne(propertyName, arguments[0]);
+            Object argument = arguments[0];
+            if (argument != null) {
+                return Restrictions.ne(propertyName, arguments[0]);
+            } else {
+                return Restrictions.isNotNull(propertyName);
+            }
         }
 
     }