Category: MVC 4

In every application there are some variables that are set by the ASP.NET  application(  ASP.NET_SessionId  cookie ) and some that are set by the programmer( cached data in Application/Session/Cache/Cookies and so on).

I wanted every time to have a page where I can “clear” / delete those – and not found. So it’s the Clearer project.

It consists of :

1. ClearerController with 2 Actions:   Index and DeleteItem
2. 2 Views : Index.cshtml and EditAppData.cshtml
3. Different Models:
   • SourceData  – enum  – can be  :  None ,        Application ,        Cache ,        Session ,        Cookies
   • AppData –  maintains Key/Value and SourceData pairs
   • ListAppData – loads data from Application , Cache , Session , Cookies  – and deletes.

To make an example, I have put in the Application_Start and Session_Start different values. So the screen is the following:

What I learn from the code:

1. The Cookies, Applications, Session , Cache items can be easily converted to an DictionaryEntry and the code can be like this:
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   1 2	DictionaryEntry de = new DictionaryEntry(item, sess[item.ToString()]); AddNew(de, SourceData.Session);

2. Code must be error prone – what if some item in Session is null ? So , if I have the Key, all is good:
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   private void AddNew(DictionaryEntry de, SourceData sd)         {             AppData ap = new AppData() { source = sd, Key = de.Key.ToString() };             try             {                 var obj = de.Value;                 ap.Value = (obj == null) ? Null : obj.ToString();             }             catch (Exception ex)             {                   ap.Value = string.Format(ErrorToString, ex.Message);             }             this.Add(ap);         }

3. The dog-food is good: I have followed my advice from msprogrammer.serviciipeweb… and it works ( used for Remove )
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   [HttpPost]      public JsonResult DeleteItem(string TheKey, int Source)      {          try          {              var lad = new ListAppData();              lad.DeleteItem(TheKey, (SourceData)Source);              return Json(new { ok = true, message = "" });          }          catch (Exception ex)          {              return Json(new { ok = false, message = ex.Message });          }                 }

4. When you pass strings in Javascript, there is a simple way to encode: HttpUtility.JavaScriptStringEncode
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   1	<a href="javascript:removeItem('@HttpUtility.JavaScriptStringEncode(Model.Key)','@((int)Model.source)','@id')">Remove</a>

Possible uses:

1. For developers –  when they want to see what happens when a cache item no longer exists
2. For developers – to put to site admins some simple tool to reload data from Cache/Application . Just edit the LoadAll function to load only Cache/Application
3. For developers  – to test easily the session. Just delete ASP.NET_SessionId  cookie – you will get another one when you refresh the page.

You can view online at http://clearer.apphb.com/Clearer
The project could be found at http://clearer.codeplex.com and have all – source code, downloadable project .

Next week it will be a Nuget item.

For more features , please leave me a comment here or on codeplex at issues
Nuget package at http://nuget.org/packages/Clearer