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Posts written in November 2013

Easy Way to Generate Strongly-Typed C# Classes From JSON

Posted in: ASP.NET, C#

In nearly all my previous projects I've worked on required some kind of manipulation with reading some form of JSON data.

To allow better integration into my application, I always create strongly-typed classes that mirror the structure of the incoming data feed. This in turn allows me to serialize the JSON and select specific properties I require. But sometimes, its quite difficult and confusing to the exact class structure right, especially when the JSON contains lots of fields of data.

When I find this is the case, I use json2csharp.com. By simply pasting the contents of your JSON, the site does all the hard work and creates all the strongly-typed classes for you.

Experts Exchange: Does The Pay for An Answer Model Work?

Posted in: Random Thoughts

In one word: No.

I've been an Experts Exchange user on and off over the last few years and always re-registered my Experts Exchange account, at times, out of pure desperation in the hope that a complex question of mine could be answered.

If I look back at all the questions I've asked throughout the year whilst being a fully paid member, the responses (or solutions as Experts Exchange call it) are by far not detailed enough for the price you pay. There have been many times when I've been very patiently waiting for some kind of response to my problem for days and even when highlighting to the moderator numerous times to get an expert to look into my issue, they seem to fail at the first hurdle...

If Experts Exchange was truly the forum where all these so called "experts" reside, they should have no problem in resolving or if not at least assisting me to a relevent solution. Majority of the time its hit or miss to whether an answer I could either find an answer from their "vast" knowledge-base.

The major problem I do have with Experts Exchange is that there is no refund policy and the customer support staff don't seem at all bothered by the fact that (in my case) four of my questions were not responded to. They are unable to see that you are paying them a service to do one thing: assist YOU!

Experts Exchange really need to rethink their pricing model considerably for the true service they provide. This has become ever so apparent since the dawn of a widely used and popular StackOverflow Q&A forum where I find the response rate higher.

Of course, I can only speak about my own experience and Experts Exchange is probably a great resource for others who are employed in a different sector of the IT industry. It all comes down to the expert answering your question. Some are really good, some not so good...

Unfortunately, it's unable to fulfil my needs. I've learnt my lesson and will not be renewing my subscription after my last cancellation.

Back in the day, there was a need for a paid service like Experts Exchange. But that's long since passed.

Instagram API: Get Access Token In ASP.NET

I've written some code that outputs images using Instagram's Developer API. The code can either output images based on a user's profile or via search term.

As you may already know, in order to get any form of information from any external API an access token is required. Before we dive into some code, the first thing that we need to do is register ourselves as an Instagram Developer by going to: http://instagram.com/developer/.

Next, we need to register a new client specifically for our intended use. In my case, all I want to do is to get all image information from my own Instagram profile.

Instagram API - Register New Client

Here, you will be supplied with Client ID and Client Secret codes. But most importantly, you will need to set an OAuth Redirect URL (or Callback URL) for user's to authenticate your application.

The strange thing I've noticed about the Instagram API is that a callback page is a compulsory requirement. Even if you are planning on carrying out something as simple as listing some images from your own profile where a public users intervention is not required.

I'm not interested in their images, I'm interested in my own. I hope Instagram changes this soon. If Twitter can allow you to retrieve tweets by simply registering your application, why can't Instagram?

From what I've read on Instagram's Google Group's is that an access token needs to only be generated once and they don't expire. But of course Instagram have stated:

"These tokens are unique to a user and should be stored securely. Access tokens may expire at any time in the future."

Just make sure you have some fail safe's in your code that carries out the re-authentication process within your application on the event access token has expired. In my own implementation, I've kept the callback page secret and new access token requests can be made within an Administration interface.

So lets get to the code.

Step 1: Authentication Request Classes

These strongly-typed classes mirror the exact structure of the JSON returned from our authentication request. Even though we only require the "access_token" property, I've added additional information, such as details on the Instagram user making the request.

public class AuthToken
{
    [JsonProperty("access_token")]
    public string AccessToken { get; set; }

    [JsonProperty("user")]
    public InstagramUser User { get; set; }
}
public class InstagramUser
{
    [JsonProperty("id")]
    public string ID { get; set; }

    [JsonProperty("username")]
    public string Username { get; set; }

    [JsonProperty("full_name")]
    public string FullName { get; set; }

    [JsonProperty("profile_picture")]
    public string ProfilePicture { get; set; }
}

It's worth noting at this point that I'm using Newtonsoft.Json framework.

Step 2: Callback Page

protected void Page_Load(object sender, EventArgs e)
{
    if (!String.IsNullOrEmpty(Request["code"]) && !Page.IsPostBack)
    {
        try
        {
            string code = Request["code"].ToString();

            NameValueCollection parameters = new NameValueCollection();
            parameters.Add("client_id", ConfigurationManager.AppSettings["instagram.clientid"].ToString());
            parameters.Add("client_secret", ConfigurationManager.AppSettings["instagram.clientsecret"].ToString());
            parameters.Add("grant_type", "authorization_code");
            parameters.Add("redirect_uri", ConfigurationManager.AppSettings["instagram.redirecturi"].ToString());
            parameters.Add("code", code);

            WebClient client = new WebClient();
            var result = client.UploadValues("https://api.instagram.com/oauth/access_token", "POST", parameters);

            var response = System.Text.Encoding.Default.GetString(result);

            var jsResult = JsonConvert.DeserializeObject(response);

            //Store Access token in database
            InstagramAPI.StoreAccessToken(jsResult.AccessToken);

            Response.Redirect("/CallbackSummary.aspx?status=success", false);
        }
        catch (Exception ex)
        {  
            EventLogProvider.LogException("Instagram - Generate Authentication Key", "INSTAGRAM", ex);

            Response.Redirect("/CallbackSummary.aspx?status=error");
        }
    }
}

As you can see, I'm redirecting the user to a "CallbackSummary" page to show if the authentication request was either a success or failure. (Remember, the page is secured within my own Administration interface.)

If the request is successful, the access token is stored.

Step 3: Request Callback Page

The last piece of the puzzle is to actually request our callback page by authorizing ourselves via Instagram API. In this case, I just have a simple page with the following mark up:

<p>If Instagram fails to output images to the page, this maybe because a new Authorisation key needs to be generated.</p>
<p>To generate a new key, press the button below and follow the required steps.</p>
<a onclick="window.open('https://api.instagram.com/oauth/authorize/?client_id=<%=ConfigurationManager.AppSettings["instagram.clientid"].ToString() %>&redirect_uri=<%=ConfigurationManager.AppSettings["instagram.redirecturi"].ToString() %>&response_type=code', 'newwindow', config='height=476,width=641,toolbar=no, menubar=no, scrollbars=no, resizable=no,location=no,directories=no, status=no'); return false;" href="#" target="_parent">Generate</a>

If all goes to plan, you should have successfully recieved the access token.

I will post more Instagram code in future posts.

C# In Depth by Jon Skeet Review

C# In Depth Third EditionWhen working as a programmer, it's really easy to continue coding in the same manner you have done since you picked up a language and made your first program.

The saying: "Why fix it if it ain't broken?" comes to mind...

I for one sometimes fail to move with the times (unknowingly to me) and find new and better ways of coding. It's only on the off chance I get introduced to different approaches through my work colleague or whilst Googling for an answer to one of my coding queries.

After reading some rave reviews on C# In Depth, written by the one and only Stackoverflow god: Jon Skeet. I decided to part with my hard earned money and make a purchase.

C# In Depth is different from other programming books I've read on C#. In fact it's really good and don't let the title of the book deter you. The contents is ideal for novice and semi-experienced programmers.

Firstly, you start off by being shown code samples on how C# has evolved through its iterations (v1 - v4). In most cases I gave myself a gratifying pat on the back when I noticed the approaches I've taken in my own projects utilised practises and features of the current language. ;-)

Secondly, unlike some programming books I've read in the past, it's not intimidating to read at all. Jon Skeet really has a great way to talk about some concepts I find difficult to comprehend in a clear a meaningful way, so I could utilise these concepts within my current applications.

The only minor niggle I have is that there were a few places where I would have liked specific chapters to go into more detail. On the other hand, it gave me the opportunity to research the nitty-gritty details for myself.

Since I purchased this book, I found myself referencing it many times and appreciating what C# has to offer along with it misconstrued and underused features.

All in all, the author truly has a gift in clearly demonstrating his understanding on the subject with finesse and if I am able to comprehend even one-tenth of his knowledge, I will be a happy man.

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