qmodel-test.js

var expect = require('expect.js');
var model = require('./qmodel.js');

describe('qmodel', function () {

  var createPersonModel = function () {
    function Person (props) {
      model.extend(this, Person, props);
    }
    Person.fields = {
      'name': model.StringField(),
      'dob': model.DateField(),
      'heightInCm': model.IntField()
    };
    model.makeModel(Person);
    return Person;
  };

  var createPersonInstance = function () {
    var Person = createPersonModel();
    var person = Person.from({
      'name': 'Fred',
      'dob': '2014-09-18',
      'heightInCm': 200
    });
    return person;
  };

  it('Can create a model', function () {
    expect(createPersonModel()).to.be.a('function');
  });

  it('Can create an instance of a model', function () {
    var person = createPersonInstance();
    expect(person.name).to.equal('Fred');
    // expect(person.dob).to.equal(???);
    expect(person.heightInCm).to.equal(200);
  });

  it('Can copy an instance of a model', function () {
    var person1 = createPersonInstance();
    var person2 = person1.copy();
    person2.name = 'Charles';
    expect(person1.name).to.equal('Fred');
    expect(person2.name).to.equal('Charles');
  });

  it('Can copy really fast? (100,000 iterations)', function () {
    var person1 = createPersonInstance();
    var person2;
    for (var i = 0; i < 100000; i++) {
      person2 = person1.copy();
      person2.heightInCm = i;
      person1 = person2; // don't just copy the same object over and over
    }
    expect(person2.heightInCm).to.equal(i-1);
  });

  it('Can copy an instance with modifications', function () {
    var person1 = createPersonInstance();
    var person2 = person1.with({
      'name': 'Charles'
    });
    expect(person1.name).to.equal('Fred');
    expect(person2.name).to.equal('Charles');
  });

  it('Can copy with modifications really fast? (100,000 iterations)', function () {
    var person1 = createPersonInstance();
    var person2;
    for (var i = 0; i < 100000; i++) {
      person2 = person1.with({heightInCm: i});
      person1 = person2; // don't just copy the same object over and over
    }
    expect(person2.heightInCm).to.equal(i-1);
  });

});

qmodel.js

var model = module.exports = {};

model.extend = function (modelInstance, modelFn, props) {
  var field;
  for (var i = 0; i < modelFn.fieldList.length; i++) {
    field = modelFn.fieldList[i];
    modelInstance[field] = props[field] || null;
  }
};

model.makeModel = function (fn) {
  if (!fn.fields) {
    throw new Error('The model must have fields set');
  }

  fn.fieldList = Object.keys(fn.fields);
  fn.from = function (obj) {
    fn.sanityCheckFields(obj);
    return new fn(obj);
  };
  fn.sanityCheckFields = function (props) {
    for (var field in props) {
      if (!fn.fields[field]) {
        throw new Error('Invalid field ' + field);
      }
      // TODO sanity checking of each field type
    }
  };

  fn.prototype.toObj = function () {
    var fields = fn.fieldList;
    var obj = {};
    var field;
    for (var i = 0; i < fields.length; i++) {
      field = fields[i];
      obj[field] = this[field];
    }
    return obj;
  };
  fn.prototype.toJSON = function () {
    return JSON.stringify(this.toObj());
  };
  fn.prototype.copy = function () {
    return new fn(this);
  };
  fn.prototype.set = function (props) {
    for (var field in props) {
      this[field] = props[field];
    }
  };
  fn.prototype.with = function (props) {
    fn.sanityCheckFields(props);
    var copy = this.copy();
    copy.set(props);
    return copy;
  };
};

model.StringField = function () {
  return true; // TODO
};

model.DateField = function () {
  return true; // TODO
};

model.IntField = function () {
  return true; // TODO
};