MVC Ajax with Dynamic Partial View Creation - asp.net-mvc-4

Question

How can I create dynamic ajax.actionlinks that will call dynamic partial views.
For example:
I have a page that will generate x number of comments
Each comment can be voted up or down (individually)
The number of up votes and down votes are counted into a single integer
Each comment div will have its own ajax.actionlink
Each ajax.actionlink will pass to the controller the ID of the comment
The controller will calculate the total votes and call the partial view to display back into the div with the correct ID.
What have I done so far:
I have been able to create successful ajax.actionlink
That will call a controller and sum the votes
That will call the partial view and display the votes
What is the issue
I don't want to hard code 30-100 different ajax.actionlinks to call 30-100 hard coded partial views.
How can I accomplish this dynamically?
Existing Code:
My ajax.actionlink inside my razor view
#Html.Raw(Ajax.ActionLink("[replacetext]", "VoteUp",
new { UserPostID = #Model.Id },
new AjaxOptions { HttpMethod = "POST", InsertionMode = InsertionMode.Replace, UpdateTargetId = "CountVote" }).ToHtmlString().Replace("[replacetext]",
"<img src=\"/Images/up_32x32.png\" />"))
My div inside the same razor view to display the returning results from the partial view.
<div id="CountVote" class="postvotes"></div>
My controller
public PartialViewResult VoteUp(int UserPostID)
{
try
{
UserVotes vote = new UserVotes();
vote.SubmitedVote = 1;
vote.UserId = Convert.ToInt32(Session["id"]);
vote.UserPostID = UserPostID;
ViewBag.SumVotes = postRepository.InsertUserPostVote(vote);
}
catch (Exception e)
{
xxx.xxx.xxxx().Raise(e);
}
return PartialView("_TotalVotes");
}
And finally my partial view (_TotalVotes.cshtml)
#ViewBag.SumVotes
Now my main view for Viewpost shows the comments in a loop using the viewbag.
foreach (var item in (List<UserComment>)ViewData["Comments"])
{
CommentVote = "cv" + i.ToString();
<div class="postlinewrapper">
<div class="postvotesframe">
<div class="postvotes">
#Html.Raw(Ajax.ActionLink("[replacetext]", "VoteUp",
new AjaxOptions { HttpMethod = "POST", InsertionMode = InsertionMode.Replace, UpdateTargetId = "CountVote" }).ToHtmlString().Replace("[replacetext]",
"<img src=\"/Images/up_32x32.png\" />"))
</div>
<div id="#CommentVote" class="#CommentVote">0</div>
<div class="postvotes">
#Html.Raw(Ajax.ActionLink("[replacetext]", "VoteDown",
new AjaxOptions { HttpMethod = "POST", InsertionMode = InsertionMode.Replace, UpdateTargetId = "CountVote" }).ToHtmlString().Replace("[replacetext]",
"<img src=\"/Images/down_32x32.png\" />"))
</div>
</div>
<div class="postleftbar">
#Html.Raw(item.Comment)
</div>
<div class="postrightbar">
<div>
<div class="post_spec">
<div class="post_spec_title">Call Sign: </div>
<div class="post_spec_detail">#item.CallSign</div>
</div>
<div class="post_spec">
<div class="post_spec_title">When: </div>
<div class="post_spec_detail">#item.CommentDate.ToString("dd/MM/yyyy")</div>
</div>
</div>
<br />
<br />
</div>
</div>
i += 1;
}
I have implemented the login to increase or decrease votes up and down:
public PartialViewResult VoteUp(int userPostId)
{
try
{
UserVotes vote = new UserVotes();
vote.SubmitedVote = 1;
vote.UserId = Convert.ToInt32(Session["id"]);
vote.UserPostID = userPostId;
ViewBag.SumVotes = postRepository.InsertUserPostVote(vote);
}
catch (Exception e)
{
xxxx.xxxx.xxxx().Raise(e);
}
return PartialView("_TotalVotes");
}
public PartialViewResult VoteDown(int userPostId)
{
try
{
UserVotes vote = new UserVotes();
vote.SubmitedVote = -1;
vote.UserId = Convert.ToInt32(Session["id"]);
vote.UserPostID = userPostId;
ViewBag.SumVotes = postRepository.InsertUserPostVote(vote);
}
catch (Exception e)
{
xxx.xxxx.xxxx().Raise(e);
}
return PartialView("_TotalVotes");
}
Now all this code works for 1 ajax call just fine, but what I need to is to display separate ajax calls for separate divs dynamically.

Answer 1

Try it this way.
Main view
I'm supposing you have a model with a collection property Comments of Comment items
#model MyNamespace.CommentAndOtherStuff
<ul>
#foreach(item in Model.Comments)
{
<li>
<a href="#Url.Action("VoteUp", "VoteControllerName", new { UserPostId = item.Id })"
class="vote-link"
data-id="#item.Id">#item.Votes</a><img src="vote.jpg" />
</li>
}
</ul>
And your controller just returns a class called VoteResult as JSON.
[HttpPost]
public ActionResult VoteUp(int UserPostID)
{
...
var model = new VoteResult
{
UserPostID = UserPostID,
Votes = service.tallyVote(UserPostID)
};
return Json(model);
}
Now hook all of those up with a jQuery event handler and setup an AJAX call
$(document).ready(function() {
$("a.vote-link").on("click", function(event) {
event.preventDefault();
var link = $(this); // the link instance that was clicked
var id = link.attr("data-id");
var url = link.attr("href");
$.ajax({
url: url,
type: "post"
})
.done(function(result) {
// JSON result: { UserPostID: 1, Votes: 5 }
// replace link text
link.html(result.Votes);
});
});
});
But I want a partial view html fagment.
[HttpPost]
public ActionResult VoteUp(int UserPostID)
{
...
var model = new VoteResult
{
UserPostID = UserPostID,
Votes = service.tallyVote(UserPostID)
};
return PartialView("_TotalVotes", model);
}
_TotalVotes partial
#model MyNamespace.VoteResult
#if (Model.Votes < 0)
{
<span class="unpopular">#Model.Votes</span>
}
else
{
<span class="awesome">#Model.Votes</span>
}
And adjust the AJAX callback
.done(function(result) {
link.html(result);
});
Now you could write a helper for the link fragment but it obfuscates things in my opinion (it's a judgement call). All you really need here is the class name and the data-id which your javascript will bind.

Answer 2

Using the Ajax helpers here seems an unnecessary overhead and I suggest you just use jquery methods to update the DOM. Your current code suggests you might be missing some logic to make a comment voting system work, including indicating what action the user may have already performed. For example (and assuming you want it to work similar to SO), if a user has previously up-voted, then clicking on the up-vote link should decrement the vote count by 1, but clicking on the down-vote link should decrement the vote count by 2 (the previous up-vote plus the new down-vote).
Refer to this fiddle for how this might be styled and behave when clicking the vote elements
Your view model for a comment might look like
public enum Vote { "None", "Up", "Down" }
public class CommentVM
{
public int ID { get; set; }
public string Text { get; set; }
public Vote CurrentVote { get; set; }
public int TotalVotes { get; set; }
}
and assuming you have a model that contains a collection of comments
public class PostVM
{
public int ID { get; set; }
public string Text { get; set; }
public IEnumerable<CommentVM> Comments { get; set; }
}
and the associated DisplayTemplate
/Views/Shared/DisplayTemplates/CommentVM.cshtml
#model CommentVM
<div class="comment" data-id="#Model.ID" data-currentvote="#Model.CurrentVote">
<div class="vote">
<div class="voteup" class="#(Model.CurrentVote == Vote.Up ? "current" : null)"></div>
<div class="votecount">#Model.TotalVotes</div>
<div class="votedown" class="#(Model.CurrentVote == Vote.Down ? "current" : null)"></div>
</div>
<div class="commenttext">#Html.DisplayFor(m => m.Text)</div>
</div>
Then in the main view
#model PostVM
.... // display some properties of Post?
#Html.DisplayFor(m => m.Comments)
<script>
var voteUpUrl = '#Url.Action("VoteUp")';
var voteDownUrl = '#Url.Action("VoteDown")';
$('.voteup').click(function() {
var container = $(this).closest('.comment');
var id = container.data('id');
var voteCount = new Number(container.find('.votecount').text());
$.post(voteUpUrl, { id: id }, function(response) {
if (!response) {
// oops, something went wrong - display error message?
return;
}
container.find('.votecount').text(response.voteCount); // update vote count
if (response.voteCount < voteCount) {
// the user previously upvoted and has now removed it
container.find('.voteup').removeClass('current');
} else if (response.voteCount == voteCount + 1) {
// the user had not previously voted on this comment
container.find('.voteup').addClass('current');
} else if (response.voteCount == voteCount + 2) {
// the user previoulsy down voted
container.find('.votedown').removeClass('current');
container.find('.voteup').addClass('current');
}
});
});
$('.votedown').click(function() {
... // similar to above (modify logic in if/elseif blocks)
});
</script>
and the controller method
public JsonResult VoteUp(int id)
{
int voteCount = // your logic to calculate the new total based on the users current vote (if any) for the comment
return Json(new { voteCount = voteCount });
}