dynamicbible/js/db.js

// js/db implements a basic wrapper for IndexedDB databases.
// See http://www.w3.org/TR/IndexedDB/ for more details about the
// IDB* interfaces referenced below.
define(
'db', {
    // Construct db wrapper.
    // If debug is true then logging will be turned on.
    Init: function(debug) {
        var self = {
            version: 1,
            dbName: "localdata",
            stores: ['settings', 'verselists'],
            debug: false,
            // Internal method not for external use.
            handleError: function(e) {
                this.debug && console.log("Error: ", e);
            },
            // Internal method not for external use.
            handleUpdate: function(e) {
                var db = e.target.result;
                e.target.transaction.onerror = this.handleError;
                for (i in this.stores) {
                    if (db.objectStoreNames.contains(this.stores[i])) {
                        // TODO(jwall): handle this more gracefully?
                        db.deleteObjectStore(this.stores[i]);
                    }
                    var store = db.createObjectStore(this.stores[i],
                                                     {keyPath: "key"});
                }
            },
            // Do operations on an open database.
            // ops is expected to be a function taking an IDBDatabase object
            // as a parameter.
            Session: function(ops) {
                var self = this;
                var req = indexedDB.open(this.dbname, this.version);
                // HandleUpgrades
                req.onupgradeneeded = function(e) {
                    self.handleUpdate(e);
                };
                req.onsuccess = function(e) {
                    ops(e.target.result);
                };
            },
            // Do operations on an open transaction scoped to the list of stores.
            // ops is expected to be a function taking an IDBTransation object
            // as a parameter.
            // type is an optional transaction type. values should be one of the
            // following: readonly or readwrite
            Transaction: function(stores, ops, type) {
                var self = this;
                var transType = type || "readonly";
                self.debug && console.log(
                    "running", transType, "transaction on stores",
                    stores);
                self.Session(
                    function(db) {
                        // Figure this api out.
                        var trans = db.transaction(stores, transType);
                        ops(trans);
                    });
            },
            // Get a key from the the object store.
            // success is expected to be a function taking an IDBRequest object
            // as a parameter.
            // error is optional and expected to be a function taking an IDBRequest
            // object as a parameter.
            Get: function(storeName, key, success, error) {
                var self = this;
                self.Transaction(
                    [storeName], function(trans) {
                        var store = trans.objectStore(storeName);
                        var req = store.get(key);
                        req.onsuccess = success;
                        req.onerror = error || self.handleError;
                    });
            },
            // Store or update a key with data in an object store.
            // success is expected to be a function taking an IDBRequest object
            // as a parameter.
            // error is optional and expected to be a function taking an IDBRequest
            // object as a parameter.
            Update: function(storeName, key, data, success, error) {
                var self = this;
                self.Transaction(
                    [storeName], function(trans) {
                        var store = trans.objectStore(storeName);
                        var req = store.put({"key": key, "data": data});
                        req.onsuccess = success;
                        req.onerror = error || self.handleError;
                    }, "readwrite");
            },
            // Delete a key from an object store.
            // success is expected to be a function taking an IDBRequest object
            // as a parameter.
            // error is optional and expected to be a function taking an IDBRequest
            // object as a parameter.
            Delete: function(storeName, key, success, error) {
                var self = this;
                self.Transaction(
                    [storeName], function(trans) {
                        var store = trans.objectStore(storeName);
                        var req = store.delete(key);
                        req.onsuccess = success;
                        req.onerror = error || self.handleError;
                    }, "readwrite");
            },
            // Query a range of values from an object store.
            // range is expected to be an IDBKeyRange.
            // success is expected to be a function taking an IDBRequest object
            // as a parameter.
            // error is optional and expected to be a function taking an IDBRequest
            // object as a parameter.
            Query: function(storeName, range, success, error) {
                var self = this;
                self.Transaction(
                    [storeName], function(trans) {
                        var store = trans.objectStore(storeName);
                        var req = store.openCursor(range);
                        req.onsuccess = success;
                        req.onerror = error || self.handleError;
                    });
            }
        };
        self.debug = debug;
        self.Session(
            function(e) {
                self.debug && console.log("Database Init complete");
            });
        return self;
    }
});