A type-safe Java library that helps your code to interact with MongoDB documents and convert them to/from Java objects. (aka pojongo)
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Monjo is a lightweight type-safe library for mapping Java objects to/from MongoDB:

  • Easy to use, and very lightweight

  • Type-safe Query support

  • Annotations describe mapping behavior; there are no XML files.

  • Extensions: Validation (jsr330), and SLF4J Logging

  • Standard Mapping: use a set of rules for determining the physical fields and collections names given the information in the mapping document (ex: naming strategy prefers embedded underscores to mixed case names)

  • Javabeans: accessors and mutators are always used to infer fields

      class Employee implements IdentificableDocument<ObjectId>{
        ObjectId id; // auto-generated, if not set (see ObjectId)
        String firstName, lastName; // value types are automatically persisted
        Long salary = null; // only non-null values are stored 
        Address address; // by default fields are embedded
        @ReferenceKey<Employee> manager; //references can be saved without automatic loading
        List<Employee> underlings = new ArrayList<Employee>(); 
           // by default, use DBList to persist inner collections
        @Indexed boolean active = false; //fields can be indexed for better performance
        @Transient int notStored; //fields can be ignored (no load/save)
        transient boolean stored = true; //not @Transient, will be ignored by Serialization/GWT for example.

Special features

  • Find By Example (find a object using any field, maybe an inner inner inner ... object )

      PojoWithListInnerObject pojo = PojoBuilder.createMegaZordePojo();
      Monjo<ObjectId, PojoWithListInnerObject> monjo = new Monjo<ObjectId, PojoWithListInnerObject>(getMongoDB(), PojoWithListInnerObject.class);
      List<Category> categories = pojo.getCategories();
      Category category = categories.get(0);
      PojoWithListInnerObject result = pojongo.findByExample(pojo.toList().get(0);
  • Cursor (select page of selection, sort and so on)

      List<SimplePOJO> list = monjo.find().limit(5).toList();
  • Update inner Objects

       monjo.<Category> updateInnerObject("categories", category, pojo);
  • Does not store Null/Empty values (by default).

  • GWT support (entities are just POJOs) -- (GWT ignores annotations)

Note: @Reference will not save objects, just a reference to them; You must save them yourself.

This library is currently at a very early development stage, but already being used in production in some really big applications.