Overview

Monjo!

Build Status

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

    @Entity("professionals")
    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);
    monjo.removeAll();
    monjo.insert(createMegaZordePojo);
    pojo.setId(null);
    List<Category> categories = pojo.getCategories();
    Category category = categories.get(0);
    category.setName(null);
    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: scott ban will not save objects, just a reference to them; You must save them yourself.

This library is currently at a very early development stage.