Azure

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Getting productive with WAMS: respect time zone offset for every single user

time_Azure

In my second post about WAMS I will show you how to respect the time zone of every user.

If you have users that are from all over the world, they have all different time zones. Your Mobile Service script runs always at UTC time, and every user gets the same date & time if you send them push notifications or update a live tile for example. Users don’t want to calculate the time zone differences, so we need to handle that for them.

UTC time is the time since 01/01/1970 00:00 in milliseconds. If we know this, it is somewhat easy to show users their local date and time.

Let’s have a look at the Windows Phone code.

To get the local time zone in our Windows Phone app, we only need three lines of code:

TimeZoneInfo localZone = TimeZoneInfo.Local;
DateTime localTime = DateTime.Now;
TimeSpan offsetToUTC = localZone.GetUtcOffset(localTime);

As you can see, we are getting the local time zone first. This is essential as this one is UTC based. Then we are creating a TimeSpan on our actual DateTime object to get the offset. To make this TimeSpan working on our Azure Mobile Service, which uses JavaScript, we need to convert it to milliseconds. That is the value that has an equal value on all programming languages.

useritemLookUp.TimezoneOffset = offsetToUTC.TotalMilliseconds;

This is the final line of code, which is used to update our user’s item in our SQL table row (for example).

Let’s have a look at the Azure code.

The code is similar to our Windows Phone part. First, we need to fetch the time zone offset from our SQL table:

var sql = "select * from users";

mssql.query(sql, {
        success: function (results) {
            if (results.length > 0) {
                for (var i = 0; i < results.length; i++) {
                    userResult = {
                                        TimeZoneOffset: results[i].TimezoneOffset,
                                        }

TimeZoneOffset = userResult.TimeZoneOffset;

This way, we can run through our whole table on an Azure Script and calculate the correct time, which is pretty easy to achieve:

var d = new Date();
var locald = new Date(d.getTime() + TimeZoneOffset);

These two lines generate the local time in Milliseconds for the specific user entry. You don’t have to worry whether a user is before or after UTC, it will always calculate the correct time.

If you want to use it for example to show the updated time to your users, you can format the time like I described earlier in this post.

That’s all about respecting local time for your users with Windows Azure and Windows Phone.

Happy coding everyone!

Posted by msicc in Azure, Dev Stories, 0 comments

Getting productive with WAMS: how to update data for a specific row in a table

WAMS.png

Like I promised, I will share some of the Azure goodness I learned during creating my last app.

This post is all about how to update a specific table entry (like a user’s data) in a Azure SQL table from an Windows Phone app.

First, we need to make sure that there is some data from the user we want to update. I used the LookupAsync () method to achieve that.

IMobileServiceTable<userItems> TableToUpdate = App.MobileService.GetTable<userItems>();
IMobileServiceTableQuery<userItems> query = TableToUpdate.Where(useritem => useritem.TwitterId == App.TwitterId);

var useritemFromAzure = await query.ToListAsync();
var useritemLookUp = await TableToUpdate.LookupAsync(useritemFromAzure.FirstOrDefault<userItems>().Id);

If we want a specific entry, we need a search criteria to find our user and fetch the id of the user’s table entry. In my case, I used the Twitter Id for the query as every user has this on my project.

Now that we have the table row id, we can easily update the data of this specific row with the UpdateAsync() method.

We need to declare which columns should be updated and asign the values to it first. After that, we simply call the UpdateAsync() method.

useritemLookUp.TwitterId = App.TwitterId;
useritemLookUp.LastCheckedAt = DateTime.Now;
useritemLookUp.OSVersion = "WP8";
useritemLookUp.AppVersion = App.VersionNumber;

await TableToUpdate.UpdateAsync(useritemLookUp);

Please note that you need a items class/model to create the update data (which you should have already before thinking about updating the data).

You should wrap this code in a try{}/catch{} block to be able to react to the Exceptions that possibly can be thrown and display a matching message to the user.

That’s already all about updating a specific row in a WAMS SQL table.

As always I hope this post is helpful for some of you.

Happy coding!

Posted by msicc in Azure, Dev Stories, 1 comment

New Series: Getting productive with Windows Azure Mobile Services (WAMS)

WAMS

Now that my current app project is near to go live, I will start a new series about how to get productive with Windows Azure Mobile Services (WAMS).

I will cover some interesting topics in this series, which are not really documented in the very well written “Getting started” series from the Azure team itself.

These topics are (list is subject to be updated if needed):

First, if you want to get  started, you should check out this link: http://www.windowsazure.com/en-us/develop/mobile/tutorials/get-started-wp8/

The tutorial makes you very easy and fast using WAMS.

What can you expect from this series? As always, I will add some of my personal experiences during my journey of creating my app. There were a lot of small stones in my way, and I will also tell you how to remove them. And of course I hope that my posts will help some of you to get their own WAMS story started.

Happy coding everyone!

Posted by msicc in Azure, Dev Stories, 0 comments

How to format Date and Time on Windows Azure

time_Azure

Phew, my first post about my journey on starting development on Windows Azure. I started a few weeks ago using the Mobile Services from Windows Azure, and I did learn a lot about it.

This post is about formatting Date and Time strings, because Azure uses a different format than my Windows Phone app.

If we upload a DateTime String to Windows Azure from a Windows Phone app, it looks like this: 2013-05-04T06:45:12.042+00:00

If we translate this, you have “YYYY-MM-DD” for the date. The letter “T” declares that the time string  is starting now, formatted “HH:MM:ss.msmsms”. The part “+00:00” is the timezone offset.

So far, probably nothing new for you.

Now let’s get to Azure. Azure by standard uses the GMT time for Date strings (DateTime() in JavaScript = Date()). I have written a scheduler which fetches data from another web service and puts it into my table. Naturally, I wanted to know when the data were last checked, so I added a column for it.

Then I did what everyone that is new to JavaScript has done and added a variable with a new Date(). And now the trouble begins. The output of new Date() is a totally different string: Sat, 04 May 2013 07:02:51 GMT.

Sure, we can parse and convert it within our app, but that would need (although not much) additional resources. So I decided to let to Azure the conversion to a Windows Phone readable string.

How do we  manipulate the Date()-string?

I binged a bit and finally found a very helpful page, that explains all about the JavaScript Date() object: http://www.elated.com/articles/working-with-dates/

I then started off with the following code:

var d = new Date();
var formattedDate = d.getFullYear() + "-" + d.getMonth() + "-" + d.getDate();
var formattedTime  = d.getHours() + ':' d.getMinutes() + ':' + d.getSeconds();
var checkedDateTime = formattedDate + "T" + t;

Those of you that are familiar with JavaScript will immediately see what I did wrong. Let me explain for the newbies:

First thing, date().getMonth is zerobased. So we will always get a result that is one month behind. We have to get it this way for the correct month:

d.getMonth()+1

But that is not all. If you will use the code above, your result will look like this: 2013-5-4T7:2:51

JavaScript does not use leading zeros. If you want to insert it into a date formatted column, you will get the following error from Azure:

Error occurred executing query: Error: [Microsoft][SQL Server Native Client 10.0][SQL Server]Conversion failed when converting date and/or time from character string.

So we need to add the leading zero before inserting it. Luckily we are able to that very easy. Here is my implementation:

var d = new Date();
var formattedDate = d.getFullYear() + "-" + ('0' + (d.getMonth()+1)).slice(-2) + "-" + ('0' + d.getDate()).slice(-2);
var formattedTime  = ('0' + d.getHours()).slice(-2) + ':' + ('0' + d.getMinutes()).slice(-2) + ':' + ('0' + d.getSeconds()).slice(-2);
var checkedDateTime = formattedDate + "T" + t;

What have we done here?

We are adding the leading 0 to each object string. The slice(-2) is for only picking the last two numbers. To make it more clear: if we have 9 as hour, adding the zero in front results in 09. Picking only the last two numbers by .slice(-2) results in still in 09. If we have 10 as hour, adding the leading zero results in 010. But the .slice(-2) operation will cut it back to 10. Easy enough, right?

If we run the code above to get the Date and Time, the result will look like this: 2013-05-04T7:02:51

The timezone offset is automatically added to the date when we update the table. If we now send the data to our Windows Phone or Windows 8 app, no conversion is needed as we already have a correctly formatted string.

I hope this is helpful for some of you and will save you some time.

Happy coding everyone!

Posted by msicc in Azure, Dev Stories, 0 comments