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IndexedDB and Date Example

· Web Dev Zone

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About an hour ago I gave a presentation on IndexedDB. One of the attendees asked about dates and being able to filter based on a date range. I told him that my assumption was that you would need to convert the dates into numbers and use a number-based range. Turns out I was wrong. Here is an example.

I began by creating an objectstore that used an index on the created field. Since our intent is to search via a date field, I decided "created" would be a good name. I also named my objectstore as "data". Boring, but it works.

var openRequest = indexedDB.open("idbpreso_date1",1);

openRequest.onupgradeneeded = function(e) {
	var thisDB = e.target.result;

	if(!thisDB.objectStoreNames.contains("data")) {
		var os = thisDB.createObjectStore("data", {autoIncrement:true});
		os.createIndex("created", "created", {unique:false});
	}
}

Next - I built a simple way to seed data. I based on a button click event to add 10 objects. Each object will have one property, created, and the date object will be based on a random date from now till 7 days in the future.

function doSeed() {
    var now = new Date();
    
    for(var i=0; i<10; i++) {
        var dayDiff = getRandomInt(1, 7);
        var thisDate = new Date();
        thisDate.setDate(now.getDate() + dayDiff);
        db.transaction(["data"],"readwrite").objectStore("data").add({created:thisDate});
    }
}
 
//Credit: Mozilla Developer Center
function getRandomInt (min, max) {
    return Math.floor(Math.random() * (max - min + 1)) + min;
}    

Note that since IndexedDB calls are asynchronous, my code should handle updating the user to let them know when the operation is done. Since this is just a quick demo though, and since that add operation will complete incredibly fast, I decided to not worry about it.

So at this point we'd have an application that lets us add data containing a created property with a valid JavaScript date. Note I didn't change it to milliseconds. I just passed it in as is.

For the final portion I added two date fields on my page. In Chrome this is rendered nicely:

Based on these, I can then create an IndexedDB range of either bounds, lowerBounds, or upperBounds. I.e., give me crap either after a date, before a date, or inside a date range.

function doSearch() {
    var fromDate = document.querySelector("#fromDate").value;
    var toDate = document.querySelector("#toDate").value;

  var range;

	if(fromDate == "" && toDate == "") return;

    var transaction = db.transaction(["data"],"readonly");
	var store = transaction.objectStore("data");
	var index = store.index("created");

    if(fromDate != "") fromDate = new Date(fromDate);
    if(toDate != "") toDate = new Date(toDate);
    
    if(fromDate != "" && toDate != "") {
		range = IDBKeyRange.bound(fromDate, toDate);
	} else if(fromDate == "") {
		range = IDBKeyRange.upperBound(toDate);
	} else {
		range = IDBKeyRange.lowerBound(fromDate);
	}

	var s = "";
	index.openCursor(range).onsuccess = function(e) {
		var cursor = e.target.result;
		if(cursor) {
			s += "<h2>Key "+cursor.key+"</h2><p>";
			for(var field in cursor.value) {
				s+= field+"="+cursor.value[field]+"<br/>";
			}
			s+="</p>";
			cursor.continue();
		}
		document.querySelector("#status").innerHTML = s;
	}

}

The only conversion required here was to take the user input and turn it into "real" date objects. Once done, everything works great:

You can run the full demo below.

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Published at DZone with permission of Raymond Camden, DZone MVB. See the original article here.

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