filer/src/providers/websql.js

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var FILE_SYSTEM_NAME = require('../constants.js').FILE_SYSTEM_NAME;
var FILE_STORE_NAME = require('../constants.js').FILE_STORE_NAME;
var WSQL_VERSION = require('../constants.js').WSQL_VERSION;
var WSQL_SIZE = require('../constants.js').WSQL_SIZE;
var WSQL_DESC = require('../constants.js').WSQL_DESC;
var Errors = require('../errors.js');
var FilerBuffer = require('../buffer.js');
var base64ArrayBuffer = require('base64-arraybuffer');
function WebSQLContext(db, isReadOnly) {
var that = this;
this.getTransaction = function(callback) {
if(that.transaction) {
callback(that.transaction);
return;
}
// Either do readTransaction() (read-only) or transaction() (read/write)
db[isReadOnly ? 'readTransaction' : 'transaction'](function(transaction) {
that.transaction = transaction;
callback(transaction);
});
};
}
WebSQLContext.prototype.clear = function(callback) {
function onError(transaction, error) {
callback(error);
}
function onSuccess(transaction, result) {
callback(null);
}
this.getTransaction(function(transaction) {
transaction.executeSql("DELETE FROM " + FILE_STORE_NAME + ";",
[], onSuccess, onError);
});
};
function _get(getTransaction, key, callback) {
function onSuccess(transaction, result) {
// If the key isn't found, return null
var value = result.rows.length === 0 ? null : result.rows.item(0).data;
callback(null, value);
}
function onError(transaction, error) {
callback(error);
}
getTransaction(function(transaction) {
transaction.executeSql("SELECT data FROM " + FILE_STORE_NAME + " WHERE id = ? LIMIT 1;",
[key], onSuccess, onError);
});
}
WebSQLContext.prototype.getObject = function(key, callback) {
_get(this.getTransaction, key, function(err, result) {
if(err) {
return callback(err);
}
try {
if(result) {
result = JSON.parse(result);
}
} catch(e) {
return callback(e);
}
callback(null, result);
});
};
WebSQLContext.prototype.getBuffer = function(key, callback) {
_get(this.getTransaction, key, function(err, result) {
if(err) {
return callback(err);
}
// Deal with zero-length ArrayBuffers, which will be encoded as ''
if(result || result === '') {
var arrayBuffer = base64ArrayBuffer.decode(result);
result = new FilerBuffer(arrayBuffer);
}
callback(null, result);
});
};
function _put(getTransaction, key, value, callback) {
function onSuccess(transaction, result) {
callback(null);
}
function onError(transaction, error) {
callback(error);
}
getTransaction(function(transaction) {
transaction.executeSql("INSERT OR REPLACE INTO " + FILE_STORE_NAME + " (id, data) VALUES (?, ?);",
[key, value], onSuccess, onError);
});
}
WebSQLContext.prototype.putObject = function(key, value, callback) {
var json = JSON.stringify(value);
_put(this.getTransaction, key, json, callback);
};
WebSQLContext.prototype.putBuffer = function(key, uint8BackedBuffer, callback) {
var base64 = base64ArrayBuffer.encode(uint8BackedBuffer.buffer);
_put(this.getTransaction, key, base64, callback);
};
WebSQLContext.prototype.delete = function(key, callback) {
function onSuccess(transaction, result) {
callback(null);
}
function onError(transaction, error) {
callback(error);
}
this.getTransaction(function(transaction) {
transaction.executeSql("DELETE FROM " + FILE_STORE_NAME + " WHERE id = ?;",
[key], onSuccess, onError);
});
};
function WebSQL(name) {
this.name = name || FILE_SYSTEM_NAME;
this.db = null;
}
WebSQL.isSupported = function() {
return !!global.openDatabase;
};
WebSQL.prototype.open = function(callback) {
var that = this;
// Bail if we already have a db open
if(that.db) {
return callback();
}
var db = global.openDatabase(that.name, WSQL_VERSION, WSQL_DESC, WSQL_SIZE);
if(!db) {
callback("[WebSQL] Unable to open database.");
return;
}
function onError(transaction, error) {
if (error.code === 5) {
callback(new Errors.EINVAL('WebSQL cannot be accessed. If private browsing is enabled, disable it.'));
}
callback(error);
}
function onSuccess(transaction, result) {
that.db = db;
callback();
}
// Create the table and index we'll need to store the fs data.
db.transaction(function(transaction) {
function createIndex(transaction) {
transaction.executeSql("CREATE INDEX IF NOT EXISTS idx_" + FILE_STORE_NAME + "_id" +
" on " + FILE_STORE_NAME + " (id);",
[], onSuccess, onError);
}
transaction.executeSql("CREATE TABLE IF NOT EXISTS " + FILE_STORE_NAME + " (id unique, data TEXT);",
[], createIndex, onError);
});
};
WebSQL.prototype.getReadOnlyContext = function() {
return new WebSQLContext(this.db, true);
};
WebSQL.prototype.getReadWriteContext = function() {
return new WebSQLContext(this.db, false);
};
module.exports = WebSQL;