Select Distinct

[theRemix]

Allow the use of find() with distinct columns. examples:

model with static fields:

var model_static = {
    fields:{
        username: "text",
        name:{
            "type":"text",
            "static":true
        },
        surname:{
            "type":"text",
            "static":true
        },
        favorites:{
            "type":"text",
            "static":false
        },
        likes:"text",
    },
    key:[["username"],"favorites","likes"]
};
var TestFindDistinctModel = ap.add_model("testfinddistinct", model_static, );

insert 3 rows with static values:

var ins = new TestFindDistinctModel();
    async.series([
        function(callback){
            ins.username = 'ab';
            ins.name = 'a';
            ins.surname = 'b';
            ins.favorites = 'x';
            ins.likes = 'xx';
            ins.save(callback);
        },
        function(callback){
            ins.username = 'ab';
            ins.name = 'a';
            ins.surname = 'b';
            ins.favorites = 'y';
            ins.likes = 'yy';
            ins.save(callback);
        },
        function(callback){
            ins.username = 'ab';
            ins.name = 'a';
            ins.surname = 'b';
            ins.favorites = 'z';
            ins.likes = 'zz';
            ins.save(callback);
        }
    ],done);

find:

TestFindDistinctModel.find({},{ distinct : ['username','name','surname']},function(err, results){
  assert.lengthOf(results, 1);
  assert.propertyVal(results[0],'username','ab');
  assert.propertyVal(results[0],'name','a');
  assert.propertyVal(results[0],'surname','b');
});