Command data access objects

Command data access objects should have an execute() method, and optionally its alternate methods. It has the hereunder arguments:

• connection
  An object with connection information to the store. It depends on the persistence procedure.
• data
  An optional object that contains the input values of the command.
• callback
  For asynchronous objects: A function with callback(err, result) signature, where err is the eventual error and result is an optional return object of the command.
• returns
  For synchronous objects: An optional object that holds the result of the command.

The following code snippet shows a sample command data access object:

var util = require('util');
var bo = require('business-objects');

var SampleCommandDao = function() {
  SampleCommandDao.super_.call(this, 'SampleCommandDao');
};
util.inherits(SampleCommandDao, bo.dataAccess.DaoBase);

SampleCommandDao.prototype.execute = function(connection, data, callback) {
  // do something using connection and data...
  // ...that produces the 'result' object
  if (err)
    callback(err);
  else {
    data.result = result;
    callback(null, data);
  }
};

The synchronous version of the above example:

var util = require('util');
var bo = require('business-objects');

var SampleCommandDao = function() {
  SampleCommandDao.super_.call(this, 'SampleCommandDao');
};
util.inherits(SampleCommandDao, bo.dataAccess.DaoBase);

SampleCommandDao.prototype.execute = function(connection, data) {
  // do something using connection and data...
  // ...that produces the 'result' object
  data.result = result;
  return data;
};