432 lines
10 KiB
JavaScript
432 lines
10 KiB
JavaScript
/*
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* DB connection and schema management class
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*/
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Scholar.DB = new function(){
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// Private members
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var _connection;
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// Privileged methods
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this.query = query;
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this.valueQuery = valueQuery;
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this.rowQuery = rowQuery;
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this.columnQuery = columnQuery;
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this.statementQuery = statementQuery;
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this.getColumns = getColumns;
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this.getColumnHash = getColumnHash;
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this.updateSchema = updateSchema;
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this.beginTransaction = beginTransaction;
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this.commitTransaction = commitTransaction;
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this.rollbackTransaction = rollbackTransaction;
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/////////////////////////////////////////////////////////////////
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//
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// Privileged methods
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//
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/////////////////////////////////////////////////////////////////
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/*
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* Run an SQL query
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*
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* Optional _params_ is an array of bind parameters in the form
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* [{'int':2},{'string':'foobar'}]
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*
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* Returns:
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* - Associative array (similar to mysql_fetch_assoc) for SELECT's
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* - lastInsertId for INSERT's
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* - TRUE for other successful queries
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* - FALSE on error
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*/
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function query(sql,params){
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var db = _getDBConnection();
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try {
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// Parse out the SQL command being used
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var op = sql.match(/^[^a-z]*[^ ]+/i);
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if (op){
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op = op.toString().toLowerCase();
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}
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// If SELECT statement, return result
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if (op=='select'){
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// Until the native dataset methods work (or at least exist),
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// we build a multi-dimensional associative array manually
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var statement = statementQuery(sql,params);
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var dataset = new Array();
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while (statement.executeStep()){
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var row = new Array();
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for(var i=0; i<statement.columnCount; i++) {
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row[statement.getColumnName(i)] = statement.getUTF8String(i);
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}
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dataset.push(row);
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}
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statement.reset();
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return dataset.length ? dataset : false;
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}
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else {
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if (params){
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var statement = statementQuery(sql,params);
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statement.execute();
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}
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else {
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Scholar.debug(sql,5);
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db.executeSimpleSQL(sql);
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}
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if (op=='insert'){
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return db.lastInsertRowID;
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}
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// DEBUG: Can't get affected rows for UPDATE or DELETE?
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else {
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return true;
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}
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}
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}
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catch (e){
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throw(e + ' (SQL error: ' + db.lastErrorString + ')');
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}
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}
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/*
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* Query a single value and return it
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*/
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function valueQuery(sql,params){
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var db = _getDBConnection();
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try {
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var statement = statementQuery(sql,params);
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}
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catch (e){
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throw(db.lastErrorString);
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}
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// No rows
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if (!statement.executeStep()){
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statement.reset();
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return false;
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}
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if (sql.indexOf('SELECT COUNT(*)') > -1){
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var value = statement.getInt32(0);
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}
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else {
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var value = statement.getUTF8String(0);
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}
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statement.reset();
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return value;
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}
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/*
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* Run a query and return the first row
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*/
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function rowQuery(sql,params){
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var result = query(sql,params);
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if (result){
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return result[0];
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}
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}
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/*
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* Run a query and return the first column as a numerically-indexed array
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*/
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function columnQuery(sql,params){
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var statement = statementQuery(sql,params);
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if (statement){
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var column = new Array();
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while (statement.executeStep()){
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column.push(statement.getUTF8String(0));
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}
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statement.reset();
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return column.length ? column : false;
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}
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return false;
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}
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/*
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* Run a query, returning a mozIStorageStatement for direct manipulation
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*
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* Optional _params_ is an array of bind parameters in the form
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* [{'int':2},{'string':'foobar'}]
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*/
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function statementQuery(sql,params){
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var db = _getDBConnection();
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try {
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Scholar.debug(sql,5);
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var statement = db.createStatement(sql);
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}
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catch (e){
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throw(db.lastErrorString);
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}
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if (statement && params){
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for (var i=0; i<params.length; i++){
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if (typeof params[i]['int'] != 'undefined'){
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Scholar.debug('Binding parameter ' + (i+1) + ': ' +
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params[i]['int'],5);
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statement.bindInt32Parameter(i,params[i]['int']);
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}
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else if (typeof params[i]['string'] != 'undefined'){
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Scholar.debug('Binding parameter ' + (i+1) + ': "' +
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params[i]['string'] + '"',5);
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statement.bindUTF8StringParameter(i,params[i]['string']);
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}
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}
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}
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return statement;
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}
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function beginTransaction(){
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var db = _getDBConnection();
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Scholar.debug('Beginning DB transaction',5);
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db.beginTransaction();
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}
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function commitTransaction(){
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var db = _getDBConnection();
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Scholar.debug('Committing transaction',5);
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db.commitTransaction();
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}
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function rollbackTransaction(){
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var db = _getDBConnection();
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Scholar.debug('Rolling back transaction',5);
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db.rollbackTransaction();
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}
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function getColumns(table){
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var db = _getDBConnection();
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try {
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var sql = "SELECT * FROM " + table + " LIMIT 1";
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var statement = statementQuery(sql);
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var cols = new Array();
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for (var i=0,len=statement.columnCount; i<len; i++){
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cols.push(statement.getColumnName(i));
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}
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return cols;
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}
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catch (e){
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Scholar.debug(e,1);
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return false;
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}
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}
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function getColumnHash(table){
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var cols = getColumns(table);
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var hash = new Array();
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if (cols.length){
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for (var i=0; i<cols.length; i++){
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hash[cols[i]] = true;
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}
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}
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return hash;
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}
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/*
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* Checks if the DB schema exists and is up-to-date, updating if necessary
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*/
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function updateSchema(){
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var DBVersion = _getDBVersion();
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if (DBVersion > SCHOLAR_CONFIG['DB_VERSION']){
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throw("Scholar DB version is newer than config version");
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}
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else if (DBVersion < SCHOLAR_CONFIG['DB_VERSION']){
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if (!DBVersion){
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Scholar.debug('Database does not exist -- creating\n');
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return _initializeSchema();
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}
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return _migrateSchema(DBVersion);
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}
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else if (SCHOLAR_CONFIG['DB_REBUILD']){
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if (confirm('Erase all data and recreate database from schema?')){
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return _initializeSchema();
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}
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}
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}
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/////////////////////////////////////////////////////////////////
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//
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// Private methods
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//
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/////////////////////////////////////////////////////////////////
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/*
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* Retrieve a link to the data store
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*/
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function _getDBConnection(){
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if (_connection){
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return _connection;
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}
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// Get the storage service
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var store = Components.classes["@mozilla.org/storage/service;1"].
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getService(Components.interfaces.mozIStorageService);
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// Get the profile directory
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var file = Components.classes["@mozilla.org/file/directory_service;1"]
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.getService(Components.interfaces.nsIProperties)
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.get("ProfD", Components.interfaces.nsILocalFile);
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// This makes file point to PROFILE_DIR/<scholar database file>
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file.append(SCHOLAR_CONFIG['DB_FILE']);
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_connection = store.openDatabase(file);
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return _connection;
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}
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/*
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* Retrieve the DB schema version
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*/
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function _getDBVersion(){
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if (_getDBConnection().tableExists('version')){
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return valueQuery("SELECT version FROM version;");
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}
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return false;
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}
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/*
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* Load in SQL schema
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*
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* Returns an _array_ of SQL statements for feeding into query()
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*/
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function _getSchemaSQL(){
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// We pull the schema from an external file so we only have to process
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// it when necessary
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var file = Components.classes["@mozilla.org/extensions/manager;1"]
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.getService(Components.interfaces.nsIExtensionManager)
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.getInstallLocation(SCHOLAR_CONFIG['GUID'])
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.getItemLocation(SCHOLAR_CONFIG['GUID']);
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file.append('schema.sql');
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// Open an input stream from file
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var istream = Components.classes["@mozilla.org/network/file-input-stream;1"]
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.createInstance(Components.interfaces.nsIFileInputStream);
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istream.init(file, 0x01, 0444, 0);
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istream.QueryInterface(Components.interfaces.nsILineInputStream);
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var line = {}, sql = '', hasmore;
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// Fetch the schema version from the first line of the file
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istream.readLine(line);
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var schemaVersion = line.value.match(/-- ([0-9]+)/)[1];
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do {
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hasmore = istream.readLine(line);
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sql += line.value + "\n";
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} while(hasmore);
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istream.close();
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if (schemaVersion!=SCHOLAR_CONFIG['DB_VERSION']){
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throw("Scholar config version does not match schema version");
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}
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return sql;
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}
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/*
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* Retrieve the version attribute of the schema SQL XML
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*/
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function _getSchemaSQLVersion(){
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var file = Components.classes["@mozilla.org/extensions/manager;1"]
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.getService(Components.interfaces.nsIExtensionManager)
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.getInstallLocation(SCHOLAR_CONFIG['GUID'])
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.getItemLocation(SCHOLAR_CONFIG['GUID']);
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file.append('schema.sql');
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// Open an input stream from file
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var istream = Components.classes["@mozilla.org/network/file-input-stream;1"]
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.createInstance(Components.interfaces.nsIFileInputStream);
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istream.init(file, 0x01, 0444, 0);
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istream.QueryInterface(Components.interfaces.nsILineInputStream);
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var line = {};
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// Fetch the schema version from the first line of the file
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istream.readLine(line);
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var schemaVersion = line.value.match(/-- ([0-9]+)/)[1];
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istream.close();
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return schemaVersion;
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}
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/*
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* Create new DB schema
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*/
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function _initializeSchema(){
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try {
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beginTransaction();
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var sql = _getSchemaSQL();
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query(sql);
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query("INSERT INTO version VALUES (" + SCHOLAR_CONFIG['DB_VERSION'] + ")");
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commitTransaction();
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}
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catch(e){
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alert(e);
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rollbackTransaction();
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}
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}
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/*
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* Migrate schema from an older version, preserving data
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*/
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function _migrateSchema(fromVersion){
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var toVersion = SCHOLAR_CONFIG['DB_VERSION'];
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var schemaVersion = _getSchemaSQLVersion();
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if (toVersion!=schemaVersion){
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throw("Scholar config version does not match schema version");
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}
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Scholar.debug('Updating DB from version ' + fromVersion + ' to ' + toVersion + '\n');
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// Step through version changes until we reach the current version
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//
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// Each block performs the changes necessary to move from the
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// previous revision to that one.
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//
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// N.B. Be sure to call _updateDBVersion(i) at the end of each block!
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for (var i=parseInt(fromVersion) + 1; i<=toVersion; i++){
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// For now, just wipe and recreate
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if (i==2){
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_initializeSchema();
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}
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if (i==3){
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// do stuff
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// _updateDBVersion(i);
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}
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}
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}
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/*
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* Update the DB schema version tag of an existing database
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*/
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function _updateDBVersion(version){
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return query("UPDATE version SET version=" + version);
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}
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}
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