Question

Using MVC 3.
(The code below was an attempt to recreate the toggle effect of stackoverflow’s checked answer)
I have a ajax actionlink when you click it calls an update to db to switch the flag/image. However it works one time, if I click it again it will not toggle. Because there is no postback, model.IsIssue is not updated (its server code). Not sure the best approach to fix the issue. Should I handle it in the code, where I check the current flag in db and pass it back to the view. Or via Jquery, not sure how to code it (my preference)?

My code in the view (toggle):

 <div>
                @Html.Raw(
                    Ajax.ActionLink("[replacethis]", 
                        "ToggleEnabled",
                                 new { questionId = question.QuestionID, reviewId = step.ReviewID, flag = question.IsIssue },
                                 new AjaxOptions { UpdateTargetId = "toggleimage" + question.QuestionID })
                   .ToHtmlString()
                   .Replace("[replacethis]",
                       string.Format("<div id='toggleimage{0}'><img src='/Content/images/{1}' border='0' alt='toggle'/></div>",
                                                                   question.QuestionID, question.IsIssue ? "issue_on.png" : "issue_off.png")
                   )
                )        

My action controller:

public ActionResult ToggleEnabled(int questionId, int reviewId, bool flag)
        {
            using (var db = new NexGenContext())
            {
                db.Database.ExecuteSqlCommand(
                           "EXEC SP_AddUpdateQuestionFlagged @QuestionID, @ReviewID",
                           new SqlParameter("@QuestionID", questionId),
                           new SqlParameter("@ReviewID", reviewId)
                       );
                return flag ? Content("<img src='/Content/images/issue_off.png' border=0  />") : Content("<img src='/Content/images/issue_on.png' border=0  />");

            }
        }

Answer 1

I would just change a css class to toggle the image.

So instead of holding the image in img … I would use a div and placing the image as a background.

So, instead of replacing the html with the DIV and IMG in it (what removes the callback to handle the click), just change the class of the div.

In your view:

<div id="myimage" class="NormalState"></div>

In JS:

$('#myimage').click(function () {
     $.ajax({
         url: 'yourControllerActionURL'
         type: 'POST',
         contentType: "application/json; charset=utf-8",
         data: {'questionId': question.QuestionID, 'reviewId': step.ReviewID, 'flag': question.IsIssue },
         success: function (data) {
            if(data.isClicked == true){
                 $('#myimage').addClass('ClickState').removeClass('NormalState');
            }
            else{
                 $('#myimage').addClass('NormalState').removeClass('ClickState');
            } 
         }
     });
});

In your CSS:

.NormalState { background-color: #ABCDEF;}
.ClickState { background-color: #FF0000;}

In your controller:

You need to return JSON with isClicked set as true or false. You could also return the css class to apply from the controller, but that way your controller knows about the view and that is not the idea of the MVC pattern. So telling the view what happenned more suitable.