define sqldatabase prototype

This will allow us to define a sqllite module later, which we'll
want to transition to in order to do away with document data storage
as well as using a full blown mysql database for a simple scanner
frontend.

js/api.js

@@ -173,7 +173,7 @@ var api = {
 	handle_attendance_req: function(mysql, api, data) {
 
 		console.log('API', 'SYNC', 'ATTENDANCE', 'Attendance data requested by API server. Sending...');
-		mysql.connect().query('SELECT * FROM `attendance`', function(err, rows) {
+		mysql.query('SELECT * FROM `attendance`', function(err, rows) {
 
 			if(err) {
 				return console.log('MYSQL', 'SYNC', 'ATTENDANCE', 'ERR', err);

js/database.js

@@ -5,6 +5,11 @@
 
 var consts = require('./constants.js');
 var date = require('./date.js');
+var sqldatabase = require('./prototypes/sqldatabase.js');
+
+const SqlServerExportStrategyName = 'mysql';
+const ExcelExportStrategyName = 'excel';
+
 
 var database = {
 
@@ -362,10 +367,7 @@ var database = {
 		console.log('MYSQL', 'Initializing event data...');
 
 		// create mysql entry for current event if it doesn't exist
-		mysql.connect()
-
-			// insert new entry into `events` table
-			.query('INSERT IGNORE INTO `events` (table_name, event_name, semester, year) VALUES ("' + scanner.getEventId() + '", "' + scanner.getEventName() + '", "' + date.get_semester() + '", "' + date.get_year() + '")', function(err) {
+		mysql.query('INSERT IGNORE INTO `events` (table_name, event_name, semester, year) VALUES ("' + scanner.getEventId() + '", "' + scanner.getEventName() + '", "' + date.get_semester() + '", "' + date.get_year() + '")', function(err) {
 
 				// tell program request has been parsed
 				mysql.isBusy = false;
@@ -380,8 +382,7 @@ var database = {
 
 				// index event's table and see which entries from database exist on it (done in case application is restarted more than once in the same event)
 				// update local database's entries with data from mysql table's entries
-				mysql.connect()
-					.query('SELECT * FROM `attendance` WHERE event_id="' + scanner.getEventId() + '"', function(err, evtRows, evtCols) {
+				mysql.query('SELECT * FROM `attendance` WHERE event_id="' + scanner.getEventId() + '"', function(err, evtRows, evtCols) {
 
 						if(err) {
 							return console.log('MYSQL', 'QUERY', 'An error occurred attempting to check previously stored data in mysql event table -> ' + err);
@@ -463,70 +464,74 @@ var database = {
 			});
 	},
 
-	init: function(scanner, mysql, api, output) {
+	init: function(scanner, sqlServer, api, output) {
+		// quick sanity check to make sure our sqlDatabase object has "sqldatabase" as its prototype
+		if(!sqlServer.isPrototypeOf(sqldatabase)) {
+			throw "provided sqlServer does not implement sqldatabase " + sqlServer.getPrototypeOf();
+		}
 
-		// before we try to populate internal database object, check to see if mysql server has any data in it
-		mysql.connect().query('SELECT * FROM `students` ORDER BY last ASC', function(err, rows, fields) {
+		// before we try to populate internal database object, check to see if SQL server has any data in it
+		sqlServer.query('SELECT * FROM `students` ORDER BY last ASC', function(err, rows, fields) {
 
 			if(err) {
 
-				// if error, assume mysql server is not available, don't use mysql server at all. Fall back to spreadsheet implementation and advertise this to console
-				console.log('WARN', 'MYSQL', 'Using spreadsheet file to populate database instead. (' + err + ')');
+				// if error, assume SQL server is not available, don't use SQL server at all. Fall back to spreadsheet implementation and advertise this to console
+				console.log('WARN', 'SQL', 'Using spreadsheet file to populate database instead. (' + err + ')');
 
 				// populate database from spreadsheet and exit
 				return scanner.populateDatabaseFromSpreadsheet(scanner, database, function(err) {
 
 					if(err) {
 						// if fallback spreadsheet implementation errors, advertise error message and exit.
 						return console.log(	'[Fatal]: There was an error populating the database using spreadsheet' +
-											'file as backup, and the mysql database as a primary means -> ' + err);
+											'file as backup, and the SQL database as a primary means -> ' + err);
 					}
 
-					database.emit('ready', ['excel']);
+					database.emit('ready', [ExcelExportStrategyName]);
 
 				});
 			}
 
 			// if no error fetching data, check to see if any data in database. don't take into account if table has been created or not
 			if(rows.length) {
 
-				// if mysql table contains data, tell program
-				mysql.hasData = true;
+				// if SQL table contains data, tell program
+				sqlServer.hasData = true;
 
 				// then, begin adding such data to internal database object
 				scanner.populateDatabaseFromMysql(scanner, database, rows, function(err) {				
 
-					if(!mysql.eventEntryCreated) {
-						database.initializeEventEntry(scanner, mysql, api, function() {
-							database.emit('ready', ['mysql']);
+					if(!sqlServer.eventEntryCreated) {
+						database.initializeEventEntry(scanner, sqlServer, api, function() {
+							database.emit('ready', [SqlServerExportStrategyName]);
 						});
 					}
 
 				});
 
 			} else {
 
-				// mysql database is empty. advertise that we are loading data from spreadsheet to populate mysql table
-				console.log('EXCEL', 'No data found on mysql server. Using spreadsheet to populate internal database.');
+				// SQL database is empty. advertise that we are loading data from spreadsheet to populate SQL table
+				console.log('EXCEL', 'No data found on SQL server. Using spreadsheet to populate internal database.');
 
 				// if no data in database, use spreadsheet data to populate our local database object, and then
-				// use the newly populated local 'database' object to populate mysql server database
+				// use the newly populated local 'database' object to populate SQL server database
 				scanner.populateDatabaseFromSpreadsheet(scanner, database, function(err) {
 
 					if(err) {
 						return console.log('[Fatal]: Error populating local database object from spreadsheet -> ' + err);
 					}
 
-					// once internal database object has data in it, export data to mysql server if empty
-					scanner.exportDatabase(scanner, database, mysql, api, output, 'mysql', consts.EXCEL_AUTOSAVE_FILE, function(err) {
+					// once internal database object has data in it, export data to SQL server if empty
+					scanner.exportDatabase(scanner, database, sqlServer, api, output, SqlServerExportStrategyName, consts.EXCEL_AUTOSAVE_FILE, function(err) {
 
 						if(err) {
-							console.log('An error occurred populating empty mysql database -> ' + err);
-							return database.emit('ready', ['excel']);
+							console.log('An error occurred populating empty SQL database -> ' + err);
+							return database.emit('ready', [ExcelExportStrategyName]);
 						}
 
-						// begin auto-saving new data to mysql database
-						database.emit('ready', ['mysql']);
+						// begin auto-saving new data to SQL database
+						database.emit('ready', [SqlServerExportStrategyName]);
 					});
 				});
 

js/mysql.js

@@ -1,21 +1,17 @@
 /**
  * define mysql connection object
+ * @implements sqldatabase interface
 **/
 
 var consts = require('./constants.js');
 var date = require('./date.js');
+var sqldatabase = require('./prototypes/sqldatabase.js');
 
 var mysql = {
-
-	// define mysql object properties
-	connection 			: 	null,				// holds the connection object to the mysql server or null if not connected
-	eventEntryCreated	: 	false,				// flag indicating whether a mysql entry has been added (`events`) for current event
-	hasData				:	false,				// flag indicating whether mysql database table contains any data
-	isBusy 				: 	false, 				// flag indicating whether a mysql query is currently ongoing
-	isConnected			: 	false,				// flag indicating whether a connection to mysql server has been established
 	library				: 	require('mysql'),	// define and import node.js package
 
 	/**
+	 * @private method
 	 * creates and establishes a connection to
 	 * the mysql server
 	 *
@@ -24,7 +20,7 @@ var mysql = {
 	 * @param password	= {String} specifying database account password
 	 * @param database 	= {String} specifying the name of database to connect to
 	**/
-	connect : function(host, user, password, database) {
+	_connect : function(host, user, password, database) {
 		// check to see if previous connection exists, or @params for new connection are passed
 		if(!mysql.isConnected || (host && user && password)) {
 			// create connection blueprint
@@ -59,6 +55,16 @@ var mysql = {
 		}
 	},
 
+	/**
+	 * performs a query using the underlying database connection
+	 *
+	 * @param sqlQuery 	= {String} 		specifying SQL query to execute
+	 * @param callback 	= {Function} 	to call after operation has completed successfully
+	**/
+	query : function(sqlQuery, callback) {
+		mysql._connect().query(sqlQuery, callback);
+	},
+
 	/**
 	 * deletes entries from table where whereLogic applies
 	 *
@@ -71,8 +77,7 @@ var mysql = {
 	deleteFrom : function(mysqlTableName, whereLogic, callback) {
 		if(whereLogic) {
 			// perform query only if whereLogic has been passed
-			mysql.connect()
-				.query('DELETE FROM ' + mysqlTableName + ' WHERE ' + (whereLogic || '1 = 1'), callback);
+			mysql.query('DELETE FROM ' + mysqlTableName + ' WHERE ' + (whereLogic || '1 = 1'), callback);
 		} else {
 			// fail and exit function with error
 			callback.call(this, 'ERR: (mysqldatabasedeletionerror): no \'WHERE\' condition applies for selected logic.');
@@ -107,8 +112,7 @@ var mysql = {
 		});
 
 		// join arrays of column names and values to add by commas and add them to our query string
-		mysql.connect()
-			.query('INSERT INTO ' + mysqlTableName + '(' + (databaseColumns.join(',')) + ') VALUES (' + valuesToAdd.join(',') + ')', 
+		mysql.query('INSERT INTO ' + mysqlTableName + '(' + (databaseColumns.join(',')) + ') VALUES (' + valuesToAdd.join(',') + ')', 
 				// call user's callback function
 				function(err) {
 					// get err param if any and pass it to callback before calling
@@ -128,8 +132,7 @@ var mysql = {
 	**/
 	selectFrom : function(mysqlTableName, databaseColumns, whereLogic, callback) {
 		// perform query
-		mysql.connect()
-			.query('SELECT ' + databaseColumns.join(',') + ' FROM ' + mysqlTableName + ' WHERE ' + (whereLogic || '1 = 1'), callback);
+		mysql.query('SELECT ' + databaseColumns.join(',') + ' FROM ' + mysqlTableName + ' WHERE ' + (whereLogic || '1 = 1'), callback);
 	},
 
 	/**
@@ -155,15 +158,16 @@ var mysql = {
 		keyValuePairs = keyValuePairs.substring(1);
 
 		// join arrays of column names and values to add by commas and add them to our query string
-		mysql.connect()
-			.query('UPDATE ' + mysqlTableName + ' SET ' + keyValuePairs + ' WHERE ' + (whereLogic || '1 = 1'), 
-				// call user's callback function
-				function(err) {
-					// get err param if any and pass it to callback before calling and exit
-					return callback.call(mysql, err);
-				});
+		mysql.query('UPDATE ' + mysqlTableName + ' SET ' + keyValuePairs + ' WHERE ' + (whereLogic || '1 = 1'), 
+			// call user's callback function
+			function(err) {
+				// get err param if any and pass it to callback before calling and exit
+				return callback.call(mysql, err);
+			}
+		);
 	}
 
 };
 
+mysql.__proto__ = sqldatabase;
 module.exports = mysql;

js/output.js

@@ -128,7 +128,7 @@ var output = {
 				}
 
 				// add to `attendance` table
-				mysql.connect().query(
+				mysql.query(
 
 					"INSERT INTO `attendance` (`student_id`, `event_id`, `is_new`)" +
 					"VALUES" +
@@ -175,7 +175,7 @@ var output = {
 				entry.addedToCurrentMysqlEventTable = true;
 
 				// add to `attendance` table
-				mysql.connect().query(
+				mysql.query(
 
 					"INSERT INTO `attendance` (`student_id`, `event_id`, `is_new`)" +
 					"VALUES" +

js/prototypes/baseproto.js

@@ -0,0 +1,14 @@
+var baseproto = {
+	_protoName: 'baseproto',
+
+	isPrototypeOf: function(obj) {
+		return obj._protoName && this._protoName === obj._protoName;
+	},
+
+	getPrototypeOf: function() {
+		return this._protoName;
+	}
+}
+
+
+module.exports = baseproto;

js/prototypes/sqldatabase.js

@@ -0,0 +1,89 @@
+/**
+ * define sqldatabase prototype
+**/
+
+var baseproto = require('./baseproto.js');
+
+var sqldatabase = {
+	_protoName : 'sqldatabase',
+
+	// define sqldatabase object properties
+	connection 			: 	null,				// holds the connection object to the SQL server or null if not connected
+	eventEntryCreated	: 	false,				// flag indicating whether a SQL entry has been added (`events`) for current event
+	hasData				:	false,				// flag indicating whether SQL database table contains any data
+	isBusy 				: 	false, 				// flag indicating whether a SQL query is currently ongoing
+	isConnected			: 	false,				// flag indicating whether a connection to SQL server has been established
+
+	/**
+	 * performs a query using the underlying database connection
+	 *
+	 * @param sqlQuery 	= {String} 		specifying SQL query to execute
+	 * @param callback 	= {Function} 	to call after operation has completed successfully
+	**/
+	query : function(sqlQuery, callback) {
+		throw "unimplemented query method";
+	},
+
+	/**
+	 * deletes entries from table where whereLogic applies
+	 *
+	 * @param sqlTableName  	= {Object}		entry object from local 'database' object
+	 * @param whereLogic 		= {String} 		containing equality to use to target the selection of a specific row
+	 * @param callback 			= {Function} 	to call after operation has completed successfully
+	 *
+	 * for data protection, if @param whereLogic is 'null', nothing should be deleted / returned
+	**/
+	deleteFrom : function(sqlTableName, whereLogic, callback) {
+		throw "unimplemented deleteFrom method";
+	},
+
+	/**
+	 * safely closes the SQL server connection
+	**/
+	end : function() {
+		throw "unimplemented end method";
+	},
+
+	/**
+	 * inserts new entry to SQL database
+	 *
+	 * @param sqlTableName  	= {Object}		entry object from local 'database' object
+	 * @param databaseColumns 	= {Array} 		containing names of SQL table columns to insert values into
+	 * @param valuesToAdd		= {Array} 		containing entry values to add
+	 * @param callback 			= {Function} 	to call after operation has completed successfully
+	**/
+	insertInto : function(sqlTableName, databaseColumns, valuesToAdd, callback) {
+		throw "unimplemented insertInto method";
+	},
+
+	/**
+	 * selects entries from table, using passed logic
+	 *
+	 * @param sqlTableName  	= {Object}		entry object from local 'database' object
+	 * @param databaseColumns 	= {Array} 		containing names of SQL table columns to select
+	 * @param whereLogic 		= {String} 		containing equality to use to target the selection of a specific row
+	 * @param callback 			= {Function} 	to call after operation has completed successfully
+	 *
+	 * if @param whereLogic is 'null', all rows are selected and returned
+	**/
+	selectFrom : function(sqlTableName, databaseColumns, whereLogic, callback) {
+		throw "unimplemented selectFrom method";
+	},
+
+	/**
+	 * updates entry in database table, using passed logic
+	 *
+	 * @param sqlTableName  	= {Object}		entry object from local 'database' object
+	 * @param databaseColumns 	= {Array} 		containing names of SQL table columns to update values
+	 * @param updatedValues		= {Array} 		containing updated entry values
+	 * @param whereLogic 		= {String} 		containing equality to use to target the update of a specific row
+	 * @param callback 			= {Function} 	to call after operation has completed successfully
+	**/
+	update : function(sqlTableName, databaseColumns, updatedValues, whereLogic, callback) {
+		throw "unimplemented update method";
+	}
+
+};
+
+sqldatabase.__proto__ = baseproto;
+module.exports = sqldatabase;

js/scanner.js

@@ -86,7 +86,7 @@ var _scanner = {
 	syncAttendanceTableWithAPIServer: function(mysql, api, callback) {
 
 		// get dataset containing hash of latest attendance result
-		mysql.connect().query('SELECT MD5(concat(student_id, event_id, is_new, COUNT(*))) AS md5, COUNT(*) AS total FROM `attendance` ORDER BY student_id DESC', function(err, rows) {
+		mysql.query('SELECT MD5(concat(student_id, event_id, is_new, COUNT(*))) AS md5, COUNT(*) AS total FROM `attendance` ORDER BY student_id DESC', function(err, rows) {
 
 			if(err) {
 				return console.log('API', 'SYNC', 'ERR', err);

js/tests/utilities.js

@@ -30,7 +30,7 @@ if(!USE_CLOUD_DB) {
 
 }
 
-mysql.connect(function(err) {
+mysql._connect(function(err) {
 
 	if(err) {
 		return console.log('MYSQL', 'ERR', err);