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Raymond Camden is a developer evangelist for Adobe. His work focuses on web standards, mobile development and Cold Fusion. He's a published author and presents at conferences and user groups on a variety of topics. He is the happily married proud father of three kids and is somewhat of a Star Wars nut. Raymond can be reached via his blog at www.raymondcamden.com or via email at raymondcamden@gmail.com Raymond is a DZone MVB and is not an employee of DZone and has posted 254 posts at DZone. You can read more from them at their website. View Full User Profile

IndexedDB in Action: Complete Sample App

05.03.2012
| 5427 views |
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After a bit more sweat and tears, I've now got a "full" (if ugly) example of an IndexedDB application. It allows you to create and delete simple notes. You can view this demo here:

http://www.raymondcamden.com/demos/2012/apr/30/test5.html

Right now this demo is Firefox only. It doesn't work in Chrome because of the bug I mentioned in my earlier blog post. Here's the code - and again - I want to mention (and credit) the excellent MDN tutorial for making this easier to build.

<!DOCTYPE html>
<html>

<head>
<script src="http://ajax.googleapis.com/ajax/libs/jquery/1.7.2/jquery.min.js"></script>
<script>
var db;

// https://developer.mozilla.org/en/IndexedDB/Using_IndexedDB
var indexedDB = window.indexedDB || window.webkitIndexedDB || window.mozIndexedDB || window.msIndexedDB;
var IDBTransaction = window.IDBTransaction || window.webkitIDBTransaction;

$(document).ready(function() {

	var openRequest = indexedDB.open("notes",5);

		//handle setup
		openRequest.onupgradeneeded = function(e) {

			console.log("running onupgradeneeded");
			var thisDb = e.target.result;

			//temp delete
			//thisDb.deleteObjectStore("note");

			//Create Note
			if(!thisDb.objectStoreNames.contains("note")) {
				console.log("I need to make the note objectstore");
				var objectStore = thisDb.createObjectStore("note", { keyPath: "id", autoIncrement:true });  
				objectStore.createIndex("title", "title", { unique: false });
			}


		}

		openRequest.onsuccess = function(e) {
			db = e.target.result;

			db.onerror = function(event) {
			  // Generic error handler for all errors targeted at this database's
			  // requests!
			  alert("Database error: " + event.target.errorCode);
			  console.dir(event.target);
			};

			displayNotes();

		}

		function displayNotes() {

			var transaction = db.transaction(["note"], IDBTransaction.READ);  
			var content="<ul>";

			transaction.oncomplete = function(event) {
	  			console.log("All done!");
	  			$("#noteList").html(content);
			};

			transaction.onerror = function(event) {
			  // Don't forget to handle errors!
			  console.dir(event);
			};

			var objectStore = transaction.objectStore("note");

			objectStore.openCursor().onsuccess = function(event) {  
			  var cursor = event.target.result;  
			  if (cursor) {  
			  	content += "<li data-key=\""+cursor.key+"\"><span class=\"label\">"+cursor.value.title+"</span>";
			  	content += " <a class=\"delete\">[Delete]</a>";
			  	content +="</li>";
			    cursor.continue();  
			  }  
			  else {  
			  	content += "</ul>";
			  	console.log("Done with cursor");
			  }  
			};  

		}

		$("#noteList").on("click", "a.delete", function(e) {
			e.preventDefault();
			var thisId = $(this).parent().data("key");
			console.log("delete "+thisId);

			var request = db.transaction(["note"], IDBTransaction.READ_WRITE)  
			                .objectStore("note")  
			                .delete(thisId);  
			request.onsuccess = function(event) {  
				displayNotes();
			};  

			return false;
		});

		$("#noteList").on("click", "li", function() {
			var thisId = $(this).data("key");
			var transaction = db.transaction(["note"]);  
			var objectStore = transaction.objectStore("note");  
			var request = objectStore.get(thisId);  
			request.onerror = function(event) {  
			  console.dir(event);
			};  
			request.onsuccess = function(event) {  
			  var note = request.result;
			  $("#noteDetail").html("<h2>"+note.title+"</h2><p>"+note.body+"</p>");
			};  
		});

		//TEMP TO REMOVE
		$("#addNoteButton").click(function() {

			var title = $("#title").val();
			var body = $("#body").val();
			
			var request = db.transaction(["note"], IDBTransaction.READ_WRITE)
							.objectStore("note")
							.add({title:title,body:body});

			request.onsuccess = function(event) {
				$("#title").val("");
				$("#body").val("");
				displayNotes();
			};

			return false;
		});

});

</script>
<style>
#noteList li span.label {
	cursor:pointer;
}
a.delete {
	color:red;
	font-size:.6em;
	cursor: pointer;
}
</style>
</head>

<body>

	<h2>Notes</h2>

	<div id="noteList"></div>
	<div id="noteDetail"></div>

	<h2>Add Note</h2>
	<form>
	<input type="text" id="title" placeholder="Title" required><br/>
	<textarea id="body" placeholder="Enter body here..." required></textarea>
	<p>
	<button id="addNoteButton">Save Note</button>
	</p>
	</form>

</body>
</html>

Nothing too scary, right? Using method chaining makes the code a bit more palatable and simpler to work with.

After getting this working, I began to look at how you can retrieve data. I guess I shouldn't be surprised (and @thefalken pointed it out to me), but you are limited to primary key lookups only.

So let me make sure that is clear. This is not a replacement for WebSQL. You cannot search. I guess - technically - you could search if you load everything up and iterate over it, but that's not really efficient. You can do range based filters, so for example, given a set of names I could go from Bob to Mary, but if I wanted to quickly find all the objects with property X set to Y and property Z set to A, then I'm out of luck. I was really thinking this was a Mongo-ish type solution, but I was wrong.

I don't know about you - but this is kind of disappointing. Maybe my opinion will change, but right now I'm sad that WebSQL is being dumped for this.

 

Published at DZone with permission of Raymond Camden, author and DZone MVB. (source)

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