Is it possible to bind data from your model to a knockout viewmodel. Heres an example:
public ActionResult Edit(int id)
{
Product product = _db.Products.FirstOrDefault(x=>x.ItemId == id);
return View(product);
}
Then in the View I would traditionally do something like so:
#model myApp.Models.Product
#using(Html.BeginForm())
{
#Html.EditorFor(x=>x.ItemName)
#Html.ValidationMessageFor(x=>x.ItemName)
<input type="submit" value="Update" />
}
But with Knockout I would create a EditProductViewModel from where I would do something like:
var EditProductViewModel = {
ItemName = ko.observable('')
};
EditProductViewModel.Edit = function() {
$.ajax({
url: "Home/Edit",
data: ko.ToJson(this),
success: function() {
// do something
}
});
};
$(function() {
ko.applyBindings(EditProductViewModel);
});
And instead of using the Html Helpers I would do something like so in my view:
<form data-bind="submit: Edit">
<input type="text" data-bind="value: ItemName" />
<input type="submit" value="Update" />
</form>
So how can I populate this with the data returned from my controller?
I don't have a any experience with knockout but it would seem to me that you would no longer want to return a view from your controller how about
return JSON(product)
that way you would get a json element of the product on your javascript success function you would need to collected the json element
$.ajax({
url: "Home/Edit",
data: ko.ToJson(this),
success: function(data) {
// map to knockout view model
}
});
and then from here you would call the map bindings.
When using knockout you have two ways to do this.
1. Load your textboxes, etc in one view. Upon loading that view for the first time convert your model to JSON upon in initial load to use by knockout.
ALL additional calls to/from go via JSON.
You can use in your View:
#Html.Raw(Json.Encode(yourModel))
Load your textboxes in your view (ie they are part of your vieW)
Trigger off on document.ready() your ajax calls to get your data from your controller, convert to JSON ie return Json(yourModel, JsonRequestBehavior.AllowGet) and bind those results roughly as you are already doing above
Note - the downside with this approach is with validation. If you have all client side validation, then this is OK as the attributes for data-* will have been written out by MVC to your textboxes, etc. If you have any server side validation, there is no 'smooth' built in integration here with knockout.
There's a decent article here:
http://www.codeproject.com/Articles/305308/MVC-Techniques-with-JQuery-JSON-Knockout-and-Cshar
but still lacks on server side validation mention.
You could serialize data to your page and then initialize knockout viewmodel with values from server.
ItemName = ko.observable(serializedModel.ItemName);
Related
I have diffrent <a> tags that normally pass a parameter to an action using asp-route="". Now i want to use AJAX t do this. each tag is supposed to pass an ID that comes from the model chats when the page loads up. (asp-route-ChatID="#Model.ID").
How can I achieve this in AJAX and pass that parameter? I tried using Data-ajax-update and Data-ajax-url but these option arent even available in Intellisense. Here is the method that i want to call
public IActionResult Chat(string ChatID)
{
Chats userchats=new Chats(); // a class that holds chats
//selecting data from the database......
return View(userchats);//returns view with the model
}
here is the <a> tag that gets clicked and it needs to pass a specific ID that comes from the model
<a > View Chat </a>
here is the <div> that needs to be updated depending on what <a> is clicked
<div id="UpdateThis"> <!--show data that comes from the method ajax calls--> </div>
How can I implement ajax here with tag helpers or any other way?
Use PartialView instead of view if you want to update div.
public IActionResult Chat(string ChatID)
{
Chats userchats=new Chats(); // a class that holds chats
//selecting data from the database......
return PartialView(userchats);//returns view with the model
}
View
<a id="btnView" data-id="1">View Chat</a>
<div id="UpdateThis"></div>
<script>
$("#btnView").click(function () {
$.post('#Url.Action("Chat")', { ChatID: $(this).data("id") }).done(function (e) {
$("#UpdateThis").html(e);
})
});
</script>
Is there a way to use AJAX on a DropDownList changed event to dynamically modify a partial view on a page?
My main page has a DropDownList (DropDownListFor) and a partial view which ONLY contains a list of "items". The items shown in this partial view are dependent upon the item selected in the DropDownList. There's a 1 to many relationship between the DropDownList item and the items in the partial view. So, when the user changes the value of the DropDownList, the content in the partial view will dynamically change to reflect the item selected in the DropDownList.
Here's my DropDownList:
<div data-role="fieldcontain">
Choose Capsule:<br />
#Html.DropDownListFor(x => x.CapsuleFK, new SelectList(Model.Capsules, "pk", "name", "pk"), new { id = "ddlCapsules" })
<br />
</div>
Here's my Partial View declaration on the same page:
<div data-role="fieldcontain">
#Html.Partial("_FillerPartial", Model.Fillers)
</div>
I'm not very familiar with Ajax, but looking at other examples, here's what I have for my Ajax:
$(document).ready(function () {
$('#ddlCapsules').change(function () {
// make ajax call to modify the filler list partial view
var selection = $('#ddlCapsules').val();
var dataToSend = { cappk: selection };
$.ajax({
url: 'Process/GetFillersByCapsule',
data: { cappk: dataToSend },
success: function (data) {
alert("server returned: " + data);
}
});
});
});
And finally, here's a screenshot of what's going on. By changing the "Choose Capsule" drop down list, I want the Filler list to update dynamically:
You can load the drop down list as a partial view from the controller using ajax.
The controller code:
[HttpGet]
public virtual ActionResult GetFillersByCapsule(string cappk)
{
var model = //Method to get capsules by pk, this returns a ViewModel that is used to render the filtered list.
return PartialView("PartialViewName", model);
}
The main view html:
<div id="filteredList">
</div >
The partial view
#model IEnumerable<MyCapsuleModel>
foreach (var x in Model)
{
//Render the appropriate filtered list html.
}
And you can load the filtered list using ajax:
$('#ddlCapsules').change(function () {
// make ajax call to modify the filler list partial view
var selection = $('#ddlCapsules').val();
var dataToSend = { cappk: selection };
$.ajax({
url: 'Process/GetFillersByCapsule',
data: { cappk: dataToSend },
success: function (data) {
$("#filteredList").empty();
$("#filteredList").html(data);
}
});
});
Hope this helps.
You can't update the partial, per se, because the partial will never be rendered again without a page reload. Once you receive the HTML, ASP is done, you're on your own at that point.
What you can do, of course, is switch out the content of a particular div or whatever using JavaScript. Your example in particular screams Knockout, so that's what I would recommend using.
Change your HTML to add a data-bind to your containing div:
<div data-role="fieldcontain" data-bind="foreach: filler">
<button data-bind="text: name"></button>
</div>
And your DropDownList:
#Html.DropDownListFor(x => x.CapsuleFK, new SelectList(Model.Capsules, "pk", "name", "pk"), new { id = "ddlCapsules", data_bind = "event: { change: updateFillers }" })
Then, some JavaScript:
var FillersViewModel = function () {
var self = this;
self.fillers = ko.observableArray([]);
self.updateFillers = function () {
var selection = $('#ddlCapsules').val();
var dataToSend = { cappk: selection };
$.ajax({
url: 'Process/GetFillersByCapsule',
data: { cappk: dataToSend },
success: function (data) {
self.fillers(data.fillers) // where `fillers` is an array
}
});
}
}
var viewModel = new FillersViewModel();
ko.applyBindings(viewModel);
This is a very simplistic example, and you'll need to do some more work to make it do everything you need it to do in your scenario, but the general idea is that every time the dropdown list is changed, Knockout will call your updateFillers method, which will execute the AJAX and put new data into the fillers observable array. Knockout automatically tracks changes to this array (hence the "observable" part), so an update is automatically triggered to any part of your page that relies on it. In this scenario, that's your div containing the buttons. The foreach binding will repeat the HTML inside for each member of the array. I've used a simple button element here just to illustrate, but you would include the full HTML required to create your particular button like interface. The text binding will drop the content of name in between the opening and closing tag. Refer to: http://knockoutjs.com/documentation/introduction.html for all the binding options you have.
There's much more you could do with this. You could implement templates instead of hard-coding your HTML to be repeated in the foreach. And, you can use your partial view to control the HTML for this template. The important part is that Knockout takes the pain out of generating all this repeating HTML for you, which is why I recommend using it.
Hope that's enough to get you started.
I am developing an ASP.Net MVC 3 Web Application. One of my Razor Views contains a few Textboxes and a Drop Down List. When the User selects an option from the Drop Down List, I need a Partial View, or something like this, to appear below the Drop Down List preferable without a post back.
The thing is, it isn't as easy as a simply JQuery Hide and Show for the Partial View, when the User selects an option from the Drop Down List, I need their option to be sent to a method in the Controller, perform some logic based on this option, and then return some data to the Partial View.
I haven't really got much experience with AJAX, but I get the feeling this is the technology I need to use in order to fulfil my problem.
Has anyone ever had to code anything similar to what I have described above? And if so, is AJAX what I need to use?
Also, if anyone knows of any tutorials or code snipets I could look at to help, that would be greatly appreciated.
Thanks.
UPDATE
I have followed Ryan's answer, but unfortunately I am still having some problems. I have created the following JavaScript file which is then referenced in my View
$(document).ready(function () {
$("#myDDL").change(ChangeEventOfDDL);
function ChangeEventOfDDL(){
var dropDownValue = $('#myDDL').val();
//alert(dropDownValue);
$.ajax({ type: "GET",
url: '#Url.Action("SomePartialView","testAjax")',
data: {
id: dropDownValue
},
success: function(data) {
$('#someDivToLoadContentTo').html(data);
}
});
}
});
View
<select id="myDDL">
<option></option>
<option value="1">F1</option>
<option value="2">F2</option>
<option value="3">ST1</option>
<option value="4">ST2</option>
</select>
<div id="someDivToLoadContentTo">
</div>
My Controller then looks like this
public class testAjaxController : Controller
{
//
// GET: /testAjax/
LocumEntities context = new LocumEntities();
public ActionResult SomePartialView(int id)
{
var test = "Hello World";
return View(test);
}
}
However, my method 'SomePartialView' never gets hit. Does anyone know why?
Thanks.
Yes Ajax would be the easiest thing to use here. There are plenty of good Ajax tutorials around, just remember that what Ajax does is effectively a background POST, so you can do everything you would normally do with MVC, except within an existing page.
The way I would get this to work would be to have your code something like this:
public class SomeController{
public ActionResult SomePartialView(){
// Do some logic
return View("SomePartial");
}
}
Your Ajax would be something like:
function ChangeEventOfDDL(){
$.ajax({
url: '#Url.Action("SomePartialView","Some")',
success: function(data) {
$('#someDivToLoadContentTo').html(data);
}
});
}
I hope that helps at least a little bit.
Crucially with Ajax, you can add a data object to the function, which is passed as a querystring. This means you can send values from your page quite easily with ajax. Working with the above example, the Javascript would be:
function ChangeEventOfDDL(){
var dropDownValue = $('#ddl').val();
$.ajax({
url: '#Url.Action("SomePartialView","Some")',
data: {
id: dropDownValue
}
success: function(data) {
$('#someDivToLoadContentTo').html(data);
}
});
}
The Id value is linked with the parameters of the method in your MVC class:
public class SomeController{
public ActionResult SomePartialView(int id){
// Do some logic
var model = MakeModelWithSupplierId(id);
return View("SomePartial",model);
}
}
And there you have an interactive partial view that has been populated with the value from your drop down.
Since a controller can also return a partial view, you can do the following:
$('#idofyourdropdown').change(function () {
var theValue = $(this).val();
$.post('#Url.Action("Action","Controller")', {nameOfParameter: theValue, function(data) {
$('#divWhereYouWantToAttachData').html(data);
});
});
On the change event of your dropdown, send the selected value to your desired controller action, which will pass it to the partial view and return the rendered html. The html is received in the data var and can be attached to the dom, wherever you want it (see jQuery documentation for this).
This is a common use case.
What you need to do is
create a controller method that can take the parameters you need (read about MVC model binding before you do so)
write javascript that will harvest the data you want from your form and make a call to your new controller method and render the results below
In jQuery it goes something like this:
$("#yourDIV").load('/area/controller/method', { property1: 'asasd', property2: 'asdasdadfa'})
The second parameter of this call should be prepared based on the data you harvest from your form. (if you don't know how, then learn javascript)
I have a view with a drop down list. The default value for this is stored in a session variable. However, the user change change this, in which case new data is entered.
I have a change handler on the drop down:
#using (Html.BeginForm())
{
#Html.DropDownListFor(model => model.SelectedID,
new SelectList(Model.SelectValues, "Key", "Value",
Model.SelectedID), "", new { onchange = "this.form.submit()" });
... more fields ...
<input type="submit" name="Save" />
}
[HttpPost]
public ActionResult Index(ViewModel vm)
{
... decide if I update my data or save the changes ...
}
I tried wrapping the select in a separate form tag, but then the value of my SelectedID not updated in my view model.
How can I determine when the form is posted from a drop down change, and when it is posted from a button click?
If you don't want to reload the entire page when the user changes the selection of the dropdown you could use AJAX to silently trigger a request to a different controller action that will do the necessary updates. For example:
#Html.DropDownListFor(
model => model.SelectedID,
new SelectList(Model.SelectValues, "Key", "Value"),
"",
new {
id = "myddl",
data_url = Url.Action("update")
}
)
and then in a separate javascript file:
$(function() {
$('#myddl').change(function() {
var form = $(this).closest('form');
$.ajax({
url: $(this).data('url'),
type: 'POST',
data: form.serialize(),
success: function() {
alert('update success');
}
});
});
});
and finally you could have a controller action responsible for the update:
[HttpPost]
public ActionResult Update(ViewModel vm)
{
... this will be triggered everytime the user changes some value in the
droipdown list
}
The simplest way would be to simply attach some behavior to those element's events and set a hidden field with the event target (which by now, should sound very familiar to __EVENTTARGET).
Like so:
$('#someButton').click(function()
{
$('#someHiddenField').val('someButton');
});
$('#someDropDown').change(function()
{
$('#someHiddenField').val('someDropDown');
});
And then your action method could inspect this value and act appropriately.
HOWEVER
It sounds like you're thinking in an outmoded concept for MVC. If you really needed some new information, you should consider using some Ajax and then having one of your action methods return a partial view if you want to update part of the page.
Is there anyway to submit a form but have it remain on the page?
Right now I'm displaying a table of objects, but each row has an editable value with each row in its own Ajax form but when I click the update button it goes to the method alright but the whole page changes.
Is there anyway to submit a form but have it remain on the page?
Of course, you could use AJAX:
#using (Html.BeginForm())
{
... some form input fields
<input type="submit" value="Go" />
}
and then unobtrusively AJAXify this form in a separate file:
$(function() {
$('form').submit(function() {
$.ajax({
url: this.action,
type: this.method,
data: $(this).serialize(),
success: function(result) {
// TODO: handle the results of the AJAX call
}
});
return false;
});
});
and to avoid writing all this javascript code you may take a look at the excellent jquery.form plugin:
$(function() {
$('form').ajaxForm(function(result) {
// TODO: handle the results of the AJAX call
});
});
Another alternative is to use the ASP.NET MVC 3 Ajax.BeginForm helper:
#using (Ajax.BeginForm(new AjaxOptions { OnSuccess = "success" }))
{
... some form input fields
<input type="submit" value="Go" />
}
and then have a success handler in javascript:
function success(result) {
// TODO: handle the results of the AJAX call
}
you will also need to include the jquery.unobtrusive-ajax.js script in addition to jquery to your page if you want to use the Ajax.* helpers.