Define a database on the device, create its schema, write an item and query data back. This should be as simple a thing as adding two numbers together.
With JayData
With JayData this is almost the case, it is 3 lines.
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$data.define(<span class="str">"Todo"</span>, { Task: String, Completed: Boolean }); $data(<span class="str">"Todo"</span>).save({Task:<span class="str">"Step 1"</span>, Completed: <span class="kwrd">false</span> }); $data(<span class="str">"Todo"</span>).query(<span class="str">"it.Task.contains('Step') && it.Completed == true"</span>); |
Without JayData
Without JayData: well over 200 lines. The below code is under further development, some features like query or indexation is just missing. With all those added it will be more then 300 lines for sure. Why writing 300 lines of code when 3 will just do the same?
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<span class="kwrd">var</span> myStorage = {}; <span class="kwrd">if</span> (window.openDatabase) { <span class="rem">//use WebSQL datasource if it is available</span> myStorage.open = <span class="kwrd">function</span> () { <span class="kwrd">var</span> dbSize = 5 * 1024 * 1024; <span class="rem">// 5MB</span> myStorage.db = openDatabase(<span class="str">"Todo"</span>, <span class="str">"1.0"</span>, <span class="str">"Todo manager"</span>, dbSize); } myStorage.createTable = <span class="kwrd">function</span> () { <span class="kwrd">var</span> db = myStorage.db; db.transaction(<span class="kwrd">function</span> (tx) { tx.executeSql(<span class="str">"CREATE TABLE IF NOT EXISTS todo(ID INTEGER PRIMARY KEY ASC, todo TEXT, added_on DATETIME)"</span>, []); }); } myStorage.init = <span class="kwrd">function</span> () { myStorage.open(); myStorage.createTable(); } <span class="rem">//save new item</span> myStorage.addTodo = <span class="kwrd">function</span> (todoText) { <span class="kwrd">var</span> db = myStorage.db; db.transaction(<span class="kwrd">function</span> (tx) { <span class="kwrd">var</span> addedOn = <span class="kwrd">new</span> Date(); tx.executeSql(<span class="str">"INSERT INTO todo(todo, added_on) VALUES (?,?)"</span>, [todoText, addedOn], myStorage.onSuccess, myStorage.onError); }); } myStorage.onError = <span class="kwrd">function</span> (tx, e) { alert(<span class="str">"There has been an error: "</span> + e.message); } myStorage.onSuccess = <span class="kwrd">function</span> (tx, r) { <span class="rem">//re-render the data.</span> myStorage.getAllTodoItems(loadTodoItems); } <span class="rem">//Read all records from DB</span> myStorage.getAllTodoItems = <span class="kwrd">function</span> () { <span class="kwrd">var</span> db = myStorage.db; db.transaction(<span class="kwrd">function</span> (tx) { tx.executeSql(<span class="str">"SELECT * FROM todo"</span>, [], loadTodoItems, myStorage.onError); }); } <span class="rem">//Process the results</span> <span class="kwrd">function</span> loadTodoItems(tx, rs) { <span class="kwrd">for</span> (<span class="kwrd">var</span> i = 0; i < rs.rows.length; i++) { console.dir(rs.rows.item(i)); } } console.log(<span class="str">"webSQL"</span>); } <span class="kwrd">else</span> { <span class="rem">//Use IndexedDB if WebSQL isn't available</span> console.log(<span class="str">"indexeddb"</span>); <span class="kwrd">var</span> indexedDB = window.indexedDB || window.webkitIndexedDB || window.mozIndexedDB; <span class="kwrd">if</span> (<span class="str">'webkitIndexedDB'</span> <span class="kwrd">in</span> window) { window.IDBTransaction = window.webkitIDBTransaction; window.IDBKeyRange = window.webkitIDBKeyRange; } <span class="kwrd">var</span> currentDateTime = <span class="kwrd">new</span> Date(); myStorage = {}; myStorage.db = <span class="kwrd">null</span>; myStorage.onerror = <span class="kwrd">function</span> (e) { console.log(e); }; <span class="kwrd">var</span> v = 1; myStorage.IDBTransactionModes = { <span class="str">"READ_ONLY"</span>: <span class="str">"readonly"</span>, <span class="str">"READ_WRITE"</span>: <span class="str">"readwrite"</span>, <span class="str">"VERSION_CHANGE"</span>: <span class="str">"versionchange"</span> }; myStorage.init = <span class="kwrd">function</span> () { <span class="kwrd">var</span> request = indexedDB.open(<span class="str">"todos"</span>, v); request.onupgradeneeded = <span class="kwrd">function</span> (e) { myStorage.db = e.target.result; <span class="kwrd">var</span> db = myStorage.db; <span class="rem">// We can only create Object stores in a setVersion transaction;</span> <span class="kwrd">if</span> (db.objectStoreNames.contains(<span class="str">"todo"</span>)) { <span class="kwrd">var</span> storeReq = db.deleteObjectStore(<span class="str">"todo"</span>); } <span class="kwrd">var</span> store = db.createObjectStore(<span class="str">"todo"</span>, { keyPath: <span class="str">"timeStamp"</span> }); } request.onsuccess = <span class="kwrd">function</span> (e) { myStorage.db = e.target.result; <span class="kwrd">var</span> db = myStorage.db; <span class="kwrd">if</span> (v != db.version && db.setVersion) { <span class="kwrd">var</span> setVrequest = db.setVersion(v); <span class="rem">// onsuccess is the only place we can create Object Stores</span> setVrequest.onerror = myStorage.onerror; setVrequest.onsuccess = <span class="kwrd">function</span> (e) { <span class="kwrd">if</span> (db.objectStoreNames.contains(<span class="str">"todo"</span>)) { db.deleteObjectStore(<span class="str">"todo"</span>); } <span class="kwrd">var</span> store = db.createObjectStore(<span class="str">"todo"</span>, { keyPath: <span class="str">"timeStamp"</span> }); db.close(); myStorage.getAllTodoItems(); }; } <span class="kwrd">else</span> myStorage.getAllTodoItems(); }; request.onerror = myStorage.onerror; } <span class="rem">//Save new object to the database</span> myStorage.addTodo = <span class="kwrd">function</span> (todoText) { <span class="kwrd">var</span> request = indexedDB.open(<span class="str">"todos"</span>, v); request.onsuccess = <span class="kwrd">function</span> (e) { myStorage.db = e.target.result; <span class="kwrd">var</span> db = myStorage.db; <span class="kwrd">var</span> trans = db.transaction([<span class="str">"todo"</span>], myStorage.IDBTransactionModes.READ_WRITE); <span class="kwrd">var</span> store = trans.objectStore(<span class="str">"todo"</span>); <span class="kwrd">var</span> data = { <span class="str">"text"</span>: todoText, <span class="str">"details"</span>: currentDateTime.getTime(), <span class="str">"dateCreated"</span>: currentDateTime.toUTCString(currentDateTime.getTime()), <span class="str">"timeStamp"</span>: <span class="kwrd">new</span> Date().getTime() }; <span class="kwrd">var</span> request = store.put(data); request.onsuccess = <span class="kwrd">function</span> (e) { db.close(); myStorage.getAllTodoItems(); }; request.onerror = <span class="kwrd">function</span> (e) { console.log(<span class="str">"Error Adding: "</span>, e); }; }; request.onerror = myStorage.onerror; }; myStorage.getAllTodoItems = <span class="kwrd">function</span> () { <span class="kwrd">var</span> request = indexedDB.open(<span class="str">"todos"</span>, v); request.onsuccess = <span class="kwrd">function</span> (e) { myStorage.db = e.target.result; <span class="kwrd">var</span> db = myStorage.db; db.onversionchange = <span class="kwrd">function</span> (evt) { alert(<span class="str">"versionchange"</span>); }; <span class="kwrd">var</span> trans = db.transaction([<span class="str">"todo"</span>], myStorage.IDBTransactionModes.READ_WRITE); <span class="kwrd">var</span> store = trans.objectStore(<span class="str">"todo"</span>); <span class="rem">// Get everything in the store;</span> <span class="kwrd">var</span> keyRange = IDBKeyRange.lowerBound(0); <span class="kwrd">var</span> cursorRequest = store.openCursor(keyRange); cursorRequest.onsuccess = <span class="kwrd">function</span> (e) { <span class="kwrd">var</span> result = e.target.result; <span class="kwrd">if</span> (!!result == <span class="kwrd">false</span>) { <span class="kwrd">return</span>; } console.dir(result.value); result.<span class="kwrd">continue</span>(); }; cursorRequest.onerror = myStorage.onerror; }; request.onerror = myStorage.onerror; }; console.log(<span class="str">"indexeddb"</span>); } <span class="rem">//Initialize the available database</span> myStorage.init(); myStorage.addTodo(<span class="str">"This is my task"</span>); myStorage.getAllTodoItems(); |