Object-Graph Navigation Language - OGNL2

If you don't know what is OGNL, then go check out https://github.com/jkuhnert/ognl

I created OGNL2, because I needed to make some changes to the original library! The most notable difference with the original library is that Ognl2 is capable of setting value to a chain of expressions like myTest2.objects[0].name=test It instantiates or expands intermediate objects, lists or maps in the path, if it is necessary

You may wondering why I did not created a pull request? because I originally derived this project about 4 years ago and accidentally lost all the source codes. There was only a compiled version left of. Since then I could not find a proper time or motivation to bring it back. Until now that I needed to make some changes to the library. That's why I decided to to make it Ognl2

MadzDNS cluster and spring-binder library are extensively using this implementation.

Other changes are notably as following:

• Added support to navigate a list of expressions and apply callbacks:

  OgnlContext context = (OgnlContext) Ognl.createDefaultContext(null, new DefaultMemberAccess(false));
  context.extend();
  MyTest3 root = new MyTest3();
  List<Map.Entry<String, Object>> bindingList = new ArrayList<>();
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.objects[0].name", "obj0_name"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.objects[0].id", "0"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.objects[1].id", "1"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.objects[1].name", "obj1_name"));
  bindingList.add(new AbstractMap.SimpleEntry<>("insideTest.id", "2"));
  bindingList.add(new AbstractMap.SimpleEntry<>("insideTest.name", "inside_2"));
  
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.id", "9"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[0].id", "7"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[0].objects[0].name", "obj3_name"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[0].objects[0].id", "3"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[0].objects[1].id", "4"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[0].objects[1].name", "obj4_name"));
  
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[1].id", "8"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[1].objects[0].name", "obj5_name"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[1].objects[0].id", "5"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[1].objects[1].id", "6"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.myTest2List[1].objects[1].name", "obj6_name"));
  
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.set[0].name", "set0"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.set[1].name", "set1"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.stringSet[0]", "stringSet0"));
  bindingList.add(new AbstractMap.SimpleEntry<>("myTest2.stringSet[1]", "stringSet1"));
  
  Ognl.getValue(bindingList, context, root);
  assertEquals(Long.valueOf(9), root.getMyTest2().getId());
  assertEquals(Long.valueOf(7), root.getMyTest2().getMyTest2List().get(0).getId());
  assertEquals(Long.valueOf(8), root.getMyTest2().getMyTest2List().get(1).getId());
  assertEquals(Long.valueOf(3), root.getMyTest2().getMyTest2List().get(0).getObjects().get(0).getId());
  assertEquals(Long.valueOf(4), root.getMyTest2().getMyTest2List().get(0).getObjects().get(1).getId());
  assertEquals(Long.valueOf(5), root.getMyTest2().getMyTest2List().get(1).getObjects().get(0).getId());
  assertEquals(Long.valueOf(6), root.getMyTest2().getMyTest2List().get(1).getObjects().get(1).getId());
  assertEquals(Long.valueOf(0), root.getMyTest2().getObjects().get(0).getId());
  Iterator<InsideTest> it = root.getMyTest2().getSet().iterator();
  assertEquals("set0", it.next().getName());
  assertEquals("set1", it.next().getName());
  Iterator<String> itStr = root.getMyTest2().getStringSet().iterator();
  assertEquals("stringSet0", itStr.next());
  assertEquals("stringSet1", itStr.next());
  assertEquals("obj0_name", root.getMyTest2().getObjects().get(0).getName());

With the help of introducing a new data structure called MapNode which represents hirarchy, and a new interface called ObjectConstructor navigation of every node in the hirarchy will call the processObjectForGet method of it which enables us to do great stuff because we can intercept and change the way the graph is going to be navigated. For example one can fetch an item from the database and assign it to the object property.

MapNode let us to query the lower levels of the hierarchy.

For example you can query if the object has any id property and get its value.

• It can expand List and Arrays
• It supports parametrized type instantiation
• And some other minor extendings