Editable data access objects - remove() method

• Editable data access objects
• create() method
• fetch() method
• insert() method
• update() method
• remove() method

Editable data access objects can have an remove() method. It saves a changed instance in the store. It has the following arguments:

• connection
  An object with connection information to the store. It depends on the persistence procedure.
• filter
  An optional object that contains the filter criteria of the data removal. It is the key of the model instance as described later.
• callback
  For asynchronous objects: A function with callback(err) signature, where err is the eventual error.
• returns
  For synchronous objects: Nothing.

The following code snippet shows a sample remove() method of an editable data access object:

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

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

SampleEditableDao.prototype.remove = function(connection, filter, callback) {
  // do something using connection and data...
  // ...that deletes an existing entry from the store
  if (err)
    callback(err);
  else
    callback(null);
};

The synchronous version of the above example:

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

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

SampleEditableDao.prototype.remove = function(connection, filter) {
  // do something using connection and data...
  // ...that deletes an existing entry from the store
  return;
};

Key of the object

The properties of a model can be flagged as keys at definition. For example:

var orderKey = new Property('orderKey', DataType.Integer, F.key | F.readOnly);
var customerName = new Property('customerName', DataType.Text);

A model usually has one key property, however, it can have more ones, or none at all. If the model has exactly one key property then the key is the value of that property. When the model has more key properties then the key is an object whose properties contain the key properties of the instance. In case of no key properties, the key is an object whose properties contain all properties of the instance, i.e. a data transfer object.

An example for one key property:

// Excerpt of model definition:
var orderItemKey = new Property('orderItemKey', DataType.Integer, F.key | F.readOnly);
var orderKey = new Property('orderKey', DataType.Integer, F.parentKey | F.readOnly);
var productName = new Property('productName', DataType.Text);

// The filter passed in remove() method:
var key = 7345;

An example for more key properties:

// Excerpt of model definition:
var orderKey = new Property('orderKey', DataType.Integer, F.key | F.parentKey | F.readOnly);
var orderLine = new Property('orderLine', DataType.Integer, F.Key);
var productName = new Property('productName', DataType.Text);

// The filter passed in remove() method:
var key = {
  orderKey: 628,
  orderLine: 3
};

An example for no key properties:

// Excerpt of model definition:
var orderNumber = new Property('orderKey', DataType.Integer, F.readOnly);
var orderLine = new Property('orderLine', DataType.Integer);
var productName = new Property('productName', DataType.Text);

// The filter passed in remove() method:
var key = {
  orderKey: 628,
  orderLine: 3,
  productName: 'white mug'
};