12 Books I will be planning to read in 2011

Taswar Bhatti December 7, 2010 No Comments

Here are some books I am planning to read for 2011, assuming that I complete 1 book a month, I may do more but these are must read for 2011. I will try to do my best to write a review for each.

Books

books, reading, self improvements

Operator ‘==’ cannot be applied to operands of type ‘System.Collections.Generic.KeyValuePair‘ and ‘‘

Taswar Bhatti November 29, 2010 No Comments

You are here beacause you probably got a Linq error, specifically Operator ‘==’ cannot be applied to operands of type ‘System.Collections.Generic.KeyValuePair‘ and ‘‘
So if you wish to do something like this to KeyValuePair using Linq

var item = myDictionary.FirstOrDefault(x => x.Key == 123);
if(item != null)
{
 //blah blah

}

var item = myDictionary.FirstOrDefault(x => x.Key == 123);

if(item != null)

{

//blah blah

}

You will get this error
Operator ‘!=’ cannot be applied to operands of type ‘System.Collections.Generic.KeyValuePair‘ and ‘‘

Since by default KeyValuePairs are struct.
To solve the issue we need to try out this

 var defaultVal = default(KeyValuePair<int, string>);
var item = myDictionary.FirstOrDefault(x => x.Key == 123);
if(!item.Equals(defaultValue)
{
 //blah blah
}

var defaultVal = default(KeyValuePair<int, string>);

var item = myDictionary.FirstOrDefault(x => x.Key == 123);

if(!item.Equals(defaultValue)

{

//blah blah

}

Hope this helps 🙂

.NET, Misc

C#, generics, programming

ASP MVC, Jquery modifying a select drop down with Json data

Taswar Bhatti November 18, 2010 2 Comments

Was coding some new functionality and though I would post this, so that others can find it helpful.
Lets say you have a form that has a checkbox that will update the select dropdown box with different values, when the checkbox is clicked.
Something like the UI below.

Your html code might look like

<input type="hidden" name="fieldId" value="123" />
Parent: <select name="FieldType" id="fieldTypeDropDown">
                        <option value="16">None</option>
                        <option value="4">Apple</option>
                        <option value="3">Orange</option>
                    </select>

Multiple: <input type="checkbox" name="fieldMultiple" id="fieldMultiple" />

Parent: <select name="FieldType" id="fieldTypeDropDown">

<option value="4">Apple</option>

<option value="3">Orange</option>

</select>

Multiple: <input type="checkbox" name="fieldMultiple" id="fieldMultiple" />

On your server side you would provide a Action Method to filter out the data, something like

[HttpGet]
        public JsonResult GetParents(int parentId, bool isMultiple)
        {
            //get from the database or something which is calling the possible parents 
            List<ParentViewModel> result = GetPossibleParents(parentId, isMultiple);

            IDictionary<string, string> dictionary = new Dictionary<string, string> {{"-1", "None"}};

            foreach(ParentViewModel item in result)
            {
                dictionary.Add(item.Id.ToString(), item.Name);
            }

            return Json(dictionary, JsonRequestBehavior.AllowGet);
        }

[HttpGet]

public JsonResult GetParents(int parentId, bool isMultiple)

{

//get from the database or something which is calling the possible parents

List<ParentViewModel> result = GetPossibleParents(parentId, isMultiple);

IDictionary<string, string> dictionary = new Dictionary<string, string> {{"-1", "None"}};

foreach(ParentViewModel item in result)

{

dictionary.Add(item.Id.ToString(), item.Name);

}

return Json(dictionary, JsonRequestBehavior.AllowGet);

}

Now we got to add the javascript to listen to the checkbox event changed, something like this in jquery, since we are getting Json Result we will have to parse the json object to populate the dropdown box.

 $('#fieldMultiple').live('change', function() {            
            var fieldId = $('#fieldId').val();
            var isMulti = false;    
            if ($(this).is(':checked')) {
                isMulti = true;                               
            }

            //call ajax now
                $ajax( {type: "POST", url: "someurl", data: { parentId: fieldId, isMultiple: isMulti},
                  success: function(data){
                         var dropDown = $('#fieldTypeDropDown');
                         //remove all the children
                         dropDown.children().remove();
                
                         //add the new children
                         $.each(data, function(key, value) {
                             dropDown.append('<option value="' + key + '">'+ value +"</option>");
                          });
                
                          //create an effect to show its updated
                        dropDown.effect('shake', {times: 4}, 100);
                  }
                });
            }
         });

$('#fieldMultiple').live('change', function() {

var fieldId = $('#fieldId').val();

var isMulti = false;

if ($(this).is(':checked')) {

isMulti = true;

}

//call ajax now

$ajax( {type: "POST", url: "someurl", data: { parentId: fieldId, isMultiple: isMulti},

success: function(data){

var dropDown = $('#fieldTypeDropDown');

//remove all the children

dropDown.children().remove();

//add the new children

$.each(data, function(key, value) {

dropDown.append('<option value="' + key + '">'+ value +"</option>");

});

//create an effect to show its updated

dropDown.effect('shake', {times: 4}, 100);

}

});

}

});

By doing so you will have something that shakes and updates the drop down box by some simple ajax calls 🙂

aspmvc, JQuery

asp .net mvc, asp mvc, Javascript, JQuery, mvc

Back from Holidays

Taswar Bhatti November 2, 2010 No Comments

So haven’t posted for a while, was in home city Hong Kong for holidays and busy with work releasing software, gonna be posting a few more things coming up this month so be tuned in 🙂

Misc

Javascript http post data to new window or pop up

Taswar Bhatti July 8, 2010 35 Comments

So was going through some legacy code to fix some security issues. One of them was there were links that were passing the data on url request. e.g NewFile.aspx?uid=1234

Rather than storing data in a session sometimes developers use shortcuts to do this, could be due to the pressure or time limit we have in shipping a product.

Aside from that lets see how we can fix this issue, what we want to accomplish is to post some data without calling server code and we can achieve that by some tricks in javascript.

Lets say you have a link that will say <a onclick=”javascript:NewFile()”>New File</a>
(Note I know this is not good again its legacy code)

   function NewFile()
   {
       window.open("NewFile.aspx?uid=1234", "", "width=800,height=600,left=100,top=100,resizable=yes,scrollbars=yes");
    }

function NewFile()

{

window.open("NewFile.aspx?uid=1234", "", "width=800,height=600,left=100,top=100,resizable=yes,scrollbars=yes");

}

Now we want to make a post request to the window and pass in the data.
Here is how we do it, I created a blank html page first and used this javascript.

   function OpenWindowWithPost(url, windowoption, name, params)
   {
            var form = document.createElement("form");
            form.setAttribute("method", "post");
            form.setAttribute("action", url);
            form.setAttribute("target", name);

            for (var i in params) {
                if (params.hasOwnProperty(i)) {
                    var input = document.createElement('input');
                    input.type = 'hidden';
                    input.name = i;
                    input.value = params[i];
                    form.appendChild(input);
                }
            }
            
            document.body.appendChild(form);
            
            //note I am using a post.htm page since I did not want to make double request to the page 
           //it might have some Page_Load call which might screw things up.
            window.open("post.htm", name, windowoption);
            
            form.submit();
            
            document.body.removeChild(form);
    }

   function NewFile()
   {
       var param = { 'uid' : '1234'};		    		
      OpenWindowWithPost("NewFile.aspx", 
      "width=730,height=345,left=100,top=100,resizable=yes,scrollbars=yes", 
      "NewFile", param);		
    }

function OpenWindowWithPost(url, windowoption, name, params)

{

var form = document.createElement("form");

form.setAttribute("method", "post");

form.setAttribute("action", url);

form.setAttribute("target", name);

for (var i in params) {

if (params.hasOwnProperty(i)) {

var input = document.createElement('input');

input.type = 'hidden';

input.name = i;

input.value = params[i];

form.appendChild(input);

}

document.body.appendChild(form);

//note I am using a post.htm page since I did not want to make double request to the page

//it might have some Page_Load call which might screw things up.

window.open("post.htm", name, windowoption);

form.submit();

document.body.removeChild(form);

}

function NewFile()

{

var param = { 'uid' : '1234'};

OpenWindowWithPost("NewFile.aspx",

"width=730,height=345,left=100,top=100,resizable=yes,scrollbars=yes",

"NewFile", param);

}

By doing so we can pass in the data to the NewFile.aspx page with a post request now, also note if you are using Request.QueryString[‘uid’] in the NewFile.aspx page you will need to change it to Request[‘uid’]

Hope this helps 🙂

ASP .NET, javascript

form submit, Javascript, popup, window

Stubbing out ServiceLocator for unit testing

Taswar Bhatti June 30, 2010 2 Comments

There are certainly many ways to stub out dependency, using constructor injection, etc etc. Here is one way to quickly stub out ServiceLocator rather than implementing ServiceLocatorStub.

Lets say you have code that uses a helper and the dependency is not quite the responsibility of that object but its the sub object that uses it. As an example the IAccessHelper uses some security server to check some values. But the AccountController doesnt use it so why inject security service in AccountController? In that case you will call a service locator to get you the AccessHelper object.

public class AccountController: Controller
{    
     public bool DoSomething()
     {
          var accessHelper = ServiceLocator.Current.GetInstance<IAccessHelper>();

           if(accessHelper.IsValid(user))
            {
                //do something
                return true;
            }

            return false;
     }

}

public class AccountController: Controller

{

public bool DoSomething()

{

var accessHelper = ServiceLocator.Current.GetInstance<IAccessHelper>();

if(accessHelper.IsValid(user))

{

//do something

return true;

}

return false;

}

Now if you wish to unit test this you will need to do quite a few things to stub it out. The quick way to do this is using property in C#

public class AccountController: Controller
{    
     public boolean DoSomething()
     {

           if(AccessHelperObject.IsValid(user))
            {
                //do something
                return truel
            }

           return false;
     }

     private IAccessHelper _accessHelper;
     public IAccessHelper AccessHelperObject 
     {
       get { return _accessHelper ?? ServiceLocator.Current.GetInstance<IAccessHelper>(); }
       set { _accessHelper = value; }
     }

}

public class AccountController: Controller

{

public boolean DoSomething()

{

if(AccessHelperObject.IsValid(user))

{

//do something

return truel

}

return false;

}

private IAccessHelper _accessHelper;

public IAccessHelper AccessHelperObject

{

get { return _accessHelper ?? ServiceLocator.Current.GetInstance<IAccessHelper>(); }

set { _accessHelper = value; }

}

So that now when you write your unit test you dont have to care about service locator you can just stub out your IAccessHelper by just passing in a mock or stub to it.

  [Test]
  public void Account_DoSomething()
  {
      var account = new AccoutController();
      var stubAccess = MockRepository.GenerateStub<IAccessHelper>();
      stubAccess.Expect(x => x.IsVaid("user")).Return(true);
      account.AccessHelperObject = stubAccess;
      var wasCalled = account.DoSomething();

     Assert.That(wasCalled, Is.True);
  }

[Test]

public void Account_DoSomething()

{

var account = new AccoutController();

var stubAccess = MockRepository.GenerateStub<IAccessHelper>();

stubAccess.Expect(x => x.IsVaid("user")).Return(true);

account.AccessHelperObject = stubAccess;

var wasCalled = account.DoSomething();

Assert.That(wasCalled, Is.True);

}

This helps one to quickly break out the dependency of an object, that would otherwise take too many lines of code to test out a simple idea.

Agile, aspmvc, Design, unit testing

C#, service locator, stub, TDD, unit testing

Json A circular reference was detected while serializing an object of type … in my asp mvc app

Taswar Bhatti June 9, 2010 7 Comments

I found this weird error when I was testing a no trivial test case in my app and was not able to find out what was wrong with it.
It appears like a Json error in my asp mvc app, although the stack really doesn’t help 🙂

ystem.InvalidOperationException: A circular reference was detected while serializing an object of type 'TermBaseMvc.ViewModels.Udf.UdfValueViewModel'.
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeCustomObject(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeEnumerable(IEnumerable enumerable, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValueInternal(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.SerializeValue(Object o, StringBuilder sb, Int32 depth, Hashtable objectsInUse, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, StringBuilder output, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj, SerializationFormat serializationFormat)
   at System.Web.Script.Serialization.JavaScriptSerializer.Serialize(Object obj)
   at System.Web.Mvc.JsonResult.ExecuteResult(ControllerContext context)
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResult(ControllerContext controllerContext, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<InvokeActionResultWithFilters>b__11()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<>c__DisplayClass16.<InvokeActionResultWithFilters>b__13()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<>c__DisplayClass16.<InvokeActionResultWithFilters>b__13()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultFilter(IResultFilter filter, ResultExecutingContext preContext, Func`1 continuation)
   at System.Web.Mvc.ControllerActionInvoker.<>c__DisplayClass14.<>c__DisplayClass16.<InvokeActionResultWithFilters>b__13()
   at System.Web.Mvc.ControllerActionInvoker.InvokeActionResultWithFilters(ControllerContext controllerContext, IList`1 filters, ActionResult actionResult)
   at System.Web.Mvc.ControllerActionInvoker.InvokeAction(ControllerContext controllerContext, String actionName)

ystem.InvalidOperationException: A circular reference was detected while serializing an object of type 'TermBaseMvc.ViewModels.Udf.UdfValueViewModel'.