Fixed incorrect handling with null arguments

Author: CollinAlpert

README.MD

@@ -64,7 +64,7 @@ You can include the Maven dependency:
 <dependency>
     <groupId>com.github.collinalpert</groupId>
     <artifactId>lambda2sql</artifactId>
-    <version>2.2</version>
+    <version>2.2.1</version>
 </dependency>
 ```
 

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>com.github.collinalpert</groupId>
     <artifactId>lambda2sql</artifactId>
-    <version>2.2</version>
+    <version>2.2.1</version>
     <packaging>jar</packaging>
 
     <name>lambda2sql</name>
@@ -51,6 +51,7 @@
     <properties>
         <java-version>13</java-version>
         <jdk.version>${java-version}</jdk.version>
+        <maven.compiler.release>${java-version}</maven.compiler.release>
         <maven.compiler.source>${java-version}</maven.compiler.source>
         <maven.compiler.target>${java-version}</maven.compiler.target>
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>

src/main/java/com/github/collinalpert/lambda2sql/SqlVisitor.java

@@ -125,6 +125,8 @@ private static String toSqlOperator(int expressionType) {
 	public StringBuilder visit(BinaryExpression e) {
 		//Handling for null parameters
 		if (e.getSecond() instanceof ParameterExpression && !arguments.top().isEmpty() && arguments.top().get(((ParameterExpression) e.getSecond()).getIndex()).getValue() == null) {
+			//If we don't pop here and there are more expressions after this one, they will work with an incorrect argument.
+			arguments.pop();
 			return Expression.unary(e.getExpressionType() == ExpressionType.Equal ? ExpressionType.IsNull : ExpressionType.IsNonNull, Boolean.TYPE, e.getFirst()).accept(this);
 		}
 

src/test/java/com/github/collinalpert/lambda2sql/test/Lambda2SqlTest.java

@@ -100,7 +100,9 @@ void testNull() {
 		SqlPredicate<IPerson> p2 = person -> person.getName() == null;
 		SqlPredicate<IPerson> p3 = person -> person.getAge() >= i && person.getAge() <= age;
 		assertPredicateEqual("`person`.`age` = 17 OR `person`.`name` IS NULL", p);
+		assertPredicateEqual("(`person`.`age` = 17 OR `person`.`name` IS NULL) AND true", p.and(x -> true));
 		assertPredicateEqual("`person`.`name` IS NULL", p2);
+		assertPredicateEqual("`person`.`name` IS NULL AND true", p2.and(x -> true));
 		assertPredicateEqual("`person`.`age` >= NULL AND `person`.`age` <= 17", p3);
 	}
 
@@ -196,6 +198,14 @@ void testContains() {
 		assertPredicateEqual("`person`.`id` NOT IN (3, 6, 9, 12)", person -> !ids3.contains(person.getId()));
 	}
 
+	@Test
+	void testLastParameterNull() {
+		String s = null;
+		SqlPredicate<IPerson> alwaysTrue = x -> true;
+		SqlPredicate<IPerson> pred = x -> x.getName() == s;
+		assertPredicateEqual("`person`.`name` IS NULL AND true", pred.and(alwaysTrue));
+	}
+
 	private void assertPredicateEqual(String expectedSql, SqlPredicate<IPerson> p) {
 		var sql = Lambda2Sql.toSql(p, "person");
 		Assertions.assertEquals(expectedSql, sql);