loopback-datasource-juggler/lib/connector.js

module.exports = Connector;

/**
 * Base class for LooopBack connector. This is more a collection of useful
 * methods for connectors than a super class
 * @constructor
 */
function Connector(name, settings) {
  this._models = {};
  this.name = name;
  this.settings = settings || {};
}

/**
 * Set the relational property to indicate the backend is a relational DB
 * @type {boolean}
 */
Connector.prototype.relational = false;

/**
 * Get types associated with the connector
 * @returns {String[]} The types for the connector
 */
Connector.prototype.getTypes = function() {
  return ['db', 'nosql'];
};

/**
 * Get the default data type for ID
 * @returns {Function} The default type for ID
 */
Connector.prototype.getDefaultIdType = function() {
  return String;
};

/**
 * Get the metadata for the connector
 * @returns {Object} The metadata object
 * @property {String} type The type for the backend
 * @property {Function} defaultIdType The default id type
 * @property {Boolean} [isRelational] If the connector represents a relational database
 * @property {Object} schemaForSettings The schema for settings object
 */
Connector.prototype.getMedadata = function () {
  if (!this._metadata) {
    this._metadata = {
      types: this.getTypes(),
      defaultIdType: this.getDefaultIdType(),
      isRelational: this.isRelational || (this.getTypes().indexOf('rdbms') !== -1),
      schemaForSettings: {}
    };
  }
  return this._metadata;
};

/**
 * Execute a command with given parameters
 * @param {String} command The command such as SQL
 * @param {Object[]} [params] An array of parameters
 * @param {Function} [callback] The callback function
 */
Connector.prototype.execute = function (command, params, callback) {
  throw new Error('query method should be declared in connector');
};

/**
 * Look up the data source by model name
 * @param {String} model The model name
 * @returns {DataSource} The data source
 */
Connector.prototype.getDataSource = function (model) {
  var m = this._models[model];
  if (!m) {
    console.trace('Model not found: ' + model);
  }
  return m && m.model.dataSource;
};

/**
 * Get the id property name
 * @param {String} model The model name
 * @returns {String} The id property name
 */
Connector.prototype.idName = function (model) {
  return this.getDataSource(model).idName(model);
};

/**
 * Get the id property names
 * @param {String} model The model name
 * @returns {[String]} The id property names
 */
Connector.prototype.idNames = function (model) {
  return this.getDataSource(model).idNames(model);
};

/**
 * Get the id index (sequence number, starting from 1)
 * @param {String} model The model name
 * @param {String} prop The property name
 * @returns {Number} The id index, undefined if the property is not part of the primary key
 */
Connector.prototype.id = function (model, prop) {
  var p = this._models[model].properties[prop];
  if (!p) {
    console.trace('Property not found: ' + model + '.' + prop);
  }
  return p.id;
};

/**
 * Hook to be called by DataSource for defining a model
 * @param {Object} modelDefinition The model definition
 */
Connector.prototype.define = function (modelDefinition) {
  if (!modelDefinition.settings) {
    modelDefinition.settings = {};
  }
  this._models[modelDefinition.model.modelName] = modelDefinition;
};

/**
 * Hook to be called by DataSource for defining a model property
 * @param {String} model The model name
 * @param {String} propertyName The property name
 * @param {Object} propertyDefinition The object for property metadata
 */
Connector.prototype.defineProperty = function (model, propertyName, propertyDefinition) {
  this._models[model].properties[propertyName] = propertyDefinition;
};

/**
 * Disconnect from the connector
 */
Connector.prototype.disconnect = function disconnect(cb) {
  // NO-OP
  cb && process.nextTick(cb);
};

/**
 * Get the id value for the given model
 * @param {String} model The model name
 * @param {Object} data The model instance data
 * @returns {*} The id value
 *
 */
Connector.prototype.getIdValue = function (model, data) {
  return data && data[this.idName(model)];
};

/**
 * Set the id value for the given model
 * @param {String} model The model name
 * @param {Object} data The model instance data
 * @param {*} value The id value
 *
 */
Connector.prototype.setIdValue = function (model, data, value) {
  if (data) {
    data[this.idName(model)] = value;
  }
};

Connector.prototype.getType = function () {
  return this.type;
};