Updating only the partial view contained in a mvc 3 page? - ajax

Question

I have a MVC 3 page that returns a list of user responses with a partial view called "memo" (which displays/add memos) for each response. When I add a memo to a response, it should update the db and the list of memos for that response. It should be partial page update via ajax, which effects only the partial view "memo".
The view Response.chtml that contains "memo":
#using (Html.BeginForm("Response", "User", FormMethod.Post, new { id = "UserResponse" }))
{
.... code removed ....
#foreach (var response in Model)
{
<div class="qna"><input type="text" id=#response.responseId value="#response.ResponseText" />
<div>#Html.Partial("_memo", response.responseId)</div>
}
.....
The partial page "_memo.chtml":
<div>add memo</div>
<ul id="memos">
#foreach (var memo in Model) {
<li>#memo.Text</li>
}
</ul>
<form method="post" id="memoForm"
action="#Url.Action("AddMemo")">
#Html.TextArea("Memo", new { rows = 5, cols = 50 })
<br />
<input type="submit" value="Add" />
</form>
Controller for view User/Response:
[HttpGet]
public ActionResult Response(id)
{
.....
return View(responses);
I just started with the code above, need help filling the blanks.
If I pass the response Id to the partial view, how do I pull the list of memos for that response? Will it involve ajax? (instead of ..Partial("_memo", response.memos))
How do I update the partial view via ajax call. What is ajax call (sample code) on the client side and how would the controller look? When the ajax call is successful, how do I update the list memos div="memos" to reflect the new memo?
Will the form action from Response conflict with form action of the partial view Memo?

Answer 1

Answers to Questions:
You shouldn't pass the responseId to the partial, you should pass the memo collection from your response object and make your partial view strongly typed to that collection.
See full code example below.
You don't need the form in the partial since you're making a simple ajax call to add the new memo. See full code example below.
This is a modified example from a project I am currently working on:
There is a bit of code to follow, so here goes:
This is my model. There are several sections on a career planning form, one of which is a section to select and update competencies. The SelectCompetencies model has a collection of competencies within it. The user will have the ability to add competencies. When they do, it will be added to the database and will update the list of competencies in the partial.
public class CareerPlanningFormViewModel
{
// code removed ...
public SelectCompetenciesModel SelectCompetencies { get; set; }
// code removed ...
}
public class SelectCompetenciesModel
{
public int CareerPlanningFormID { get; set; }
public IList<CompetencyModel> Competencies { get; set; }
public byte MaximumCompetenciesAllowed { get; set; }
}
public class CompetencyModel
{
public int CompetencyID { get; set; }
public int? CompetencyOptionID { get; set; }
public string ActionPlan { get; set; }
public IDictionary<int, string> CompetencyOptions { get; set; }
}
The main view of the career planning form: /Views/CPF/CareerPlanningForm.cshtml
#model MyNamespace.Models.CareerPlanningForm.CareerPlanningFormViewModel
<link rel="stylesheet" href="#Url.Content("~/Content/CreateCPF.css")" />
#using (Html.BeginForm())
{
// other sections loaded here...
// code removed for brevity...
#Html.Partial("SelectCompetencies", Model.SelectCompetencies)
// other sections loaded here...
// code removed for brevity...
}
The SelectCompetencies partial: /Views/CPF/SelectCompetencies.cshtml
The user will fill in the new action plan text and click the add competency button.
That will post via ajax to CPFController/NewCompetencyTemplate
#model MyNamespace.Models.CareerPlanningForm.SelectCompetenciesModel
#Html.HiddenFor(m => m.CareerPlanningFormID)
<h3>Select Competencies</h3>
<p class="guidance">
Select up to #Model.MaximumCompetenciesAllowed competencies to focus on improving.
</p>
<table id="CompetenciesTable">
<thead>
<tr>
<th>Competency</th>
<th>Action Plan:</th>
</tr>
</thead>
<tbody>
#for (int i = 0; i < Model.Competencies.Count(); i++)
{
#Html.EditorFor(m => m.Competencies[i])
}
</tbody>
<tfoot id="CompetenciesTableFooter" class="#(Model.Competencies.Count() < Model.MaximumCompetenciesAllowed ? "" : "hidden")">
<tr>
<td colspan="2">
#Html.TextArea("NewActionPlanText")
#Html.Button(ButtonType.Button, "Add Another Competency", "add", new { id = "AddCompetencyButton" })
</td>
</tr>
</tfoot>
</table>
#section script
{
<script>
jQuery(document).ready(function ($) {
var competenciesTableBody = $('#CompetenciesTable tbody'),
competenciesTableFooter = $('#CompetenciesTableFooter'),
addCompetencyButton = $('#AddCompetencyButton'),
newCompetencyTemplateUrl = '#Url.Content("~/CPF/NewCompetencyTemplate")',
count = competenciesTableBody.find('tr').length,
newActionPlanText = $('#NewActionPlanText'),
careerPlanningFormID = $('#CareerPlanningFormID');
addCompetencyButton.click(function () {
$.ajax({
url: newCompetencyTemplateUrl(),
type: 'POST',
data: {
careerPlanningFormID: careerPlanningFormID,
actionPlan: newActionPlanText,
itemCount: count
},
dataType: 'html',
success: function (data) {
var elements = $(data);
// other code removed here...
competenciesTableBody.append(elements);
// other code removed here...
}
});
});
});
</script>
}
Views/CPF/EditorTemplates/CompetencyModel.cshtml
#model MyNamespace.Models.CareerPlanningForm.CompetencyModel
<tr class="competency">
<td>
#Html.DropDownListFor(m => m.CompetencyOptionID, new SelectList(Model.CompetencyOptions, "Key", "Value"), "Select competency...")
</td>
<td>
#Html.TextAreaFor(m => m.ActionPlan, new { #class = "competencyActionPlan" })
#Html.HiddenFor(m => m.CompetencyID)
</td>
</tr>
The controller containing the action to add the new competency: /Controllers/CPFController.cs
This will call the CareerPlanningFormService to add the new competency and will return a partial view for NewCompetencyTemplate that will render out the new competency
public class CPFController : Controller
{
private readonly ICareerPlanningFormService careerPlanningFormService;
public CPFController(ICareerPlanningFormService careerPlanningFormService)
{
this.careerPlanningFormService = careerPlanningFormService;
}
[HttpPost]
public PartialViewResult NewCompetencyTemplate(int careerPlanningFormID, int itemCount, string newActionPlanText)
{
var count = itemCount + 1;
// Even though we're only rendering a single item template, we use a list
// to trick MVC into generating fields with correctly indexed name attributes
// i.e. Competencies[1].ActionPlan
var model = new SelectCompetenciesModel
{
Competencies = Enumerable.Repeat<CompetencyModel>(null, count).ToList()
};
model.Competencies[count - 1] = this.careerPlanningFormService.BuildNewCompetencyModel(careerPlanningFormID, newActionPlanText);
return this.PartialView(model);
}
}
My service class: CareerPlanningFormService.cs
This handles the business logic and makes the calls to the repository to add the item to the database and returns a new CompetencyModel
public class CareerPlanningFormService : ICareerPlanningFormService
{
private readonly IMyRenamedRepository repository;
private readonly IPrincipal currentUser;
public CareerPlanningFormService(
IMyRenamedRepository repository,
IPrincipal currentUser)
{
this.repository = repository;
this.currentUser = currentUser;
}
public CompetencyModel BuildNewCompetencyModel(int careerPlanningFormID, string newActionPlanText)
{
var competency = new Competency
{
CareerPlanningFormID = careerPlanningFormID,
CompetencyOptionID = null,
ActionPlan = newActionPlanText
};
this.repository.Add(competency);
this.repository.Commit();
return new CompetencyModel
{
CompetencyID = competency.CompetencyID,
CompetencyOptionID = competency.CompetencyOptionID,
ActionPlan = competency.ActionPlan,
CompetencyOptions = this.GetCompetencyOptionsForCareerPlanningFormID(careerPlanningFormID)
};
}
}
Now, the partial for NewCompetencyTemplate: Views/CPF/NewCompetencyTemplate.cshtml
This is very simple, it simply renders the same editor template as above, for the last competency in the collection (which we just added)
#model MyNamespace.Models.CareerPlanningForm.SelectCompetenciesViewModel
#Html.EditorFor(m => m.Competencies[Model.Competencies.Count() - 1])
When the ajax call succeeds, it will receive this partial back from the controller action method it called. It then takes the partial and appends it to the competencies table body
// snippet from ajax call above
competenciesTableBody.append(elements);
I hope this helps. Let me know if you have any additional questions.

Answer 2

While you're correct that you can do it just by returning a partial view containing the updated content, you may also consider using jQuery's load method.
Look here, in particular at the "loading page fragments" section. Basically you can just get the original page again and jQuery will "extract" the content you want as long as it can be targetted by a selector (such as a div id).
Note, this solution is not suitable in all cases as there will be redundant markup in the response from the server because you will be discarding the rest of the page content and just using the updated part.