I have an MVC 5 project with a form where the user can select multiple files to upload. However each file needs to have an additional integer value indicating its type. How do I implement this so the post method receives the collection of HttpPostedFileBase objects, along with each having the type value?
It will "just work", as long as your POSTed data is in the right format. The MVC model binder should just hook things up. If you've already gotten your controller action to receive an array of HttpPostedFileBase objects, you should just be able to have another argument to your action that is the array of integers `int[] fileTypes'. In your form, you will need input elements that contain those integers, with NAME attributes that allow the MVC model binder to bind the collection properly, which usually means you'd have input elements like this on your page:
<input type="hidden" value="3" name="fileTypes[0]" />
<input type="hidden" value="5" name="fileTypes[1]" />
With something like that you'd have a controller action that looked like
public ActionResult UploadMultipleFiles(HttpPostedFileBase[] uploadedFiles, int[] fileTypes)
The model binder will actually take care of hooking the input arguments up for you, as long as they were named properly on the HTML form.
If you are doing your upload via AJAX POST, the same still holds, you just have to make sure that you put the fileTypes values in as form variables with the right key names for collection binding.
Related
Is there an attribute or something similar in Asp MVC to indicate that a property should only come from the client, i.e. it shouldn't be roundtripped.
So
#Html.HiddenFor(x => x.MyProp)
I set this somehow on the client together with some other properties, it goes the server, server has a model error so sends it all back. I don't want this one property to be roundtripped.
The best I can think of is to do this
<input type="hidden" name=MyPropOneWay />
Then I manually insert it at the controller end into the property
(Addition)
It's not to avoid model errors, it's because there are a few ways of submitting the form, this is a shortcut method. In no circumstance do I want this value to be roundtripped as otherwise it will look like it's been set when it hasn't, however I do want everything else to be roundtripped
Thanks
If you don't want the value rendered from the server (either initially or after a roundtrip), use:
<input type="hidden" name="#Html.NameFor(m => m.MyProp)" />
This will render an input hidden element without a value, but it will still have the correct name to automatically bind to your model on form submission. Which effectively makes it "one way".
(The NameFor helper was added in MVC4)
I have an MVC 5 / Bootstrap application. On one of the pages, I have a number of fields all bound to the model associated with the page. However, I also have a simple unordered list which always starts out empty and the user can then add items to it. They do this by entering some text into a type ahead field. Once the user finds what he/she is looking for, he/she can click a button and have it added to the unordered list. Any number of items can be added to the list. All of this works fine.
My question is how I can get the contents of the unordered list posted back to the server along with the rest of the form contents, since the unordered list isn't part of the model?
Here is one way to skin this cat:
A) Add a collection to your model (which really should be a ViewModel, and not a domain model) to hold those items
B) In your button's click handler, create a hidden input field that conforms to the ASP.Net Wire Format: http://www.hanselman.com/blog/ASPNETWireFormatForModelBindingToArraysListsCollectionsDictionaries.aspx
If you had a collection of orders, you should end up generating controls like this:
<input type="hidden" name="Orders[0].Id" value="1" />
<input type="hidden" name="Orders[1].Id" value="2" />
Note sequential ordering is important, if you start removing items, you'll need to re-sequence your name values.
There couple of ways to work it out.
If you don't want to add to model, what I would prefer to do you can:
Directly access item that were posted via Controller.Request property;
You can post this items separately via Ajax request, and handle them in different controller action.
I have a small problem.
I want to have dropdown list with some objects. After clicking on one I want to add it to list with textfield for naming it. I don't want to limit quantity of this fields. I want to receive in controller ID (stored in dropdown list) and name (given by user) for each selected item. How can I do it?
I was thinking about storing it in some fields as a text, and parsing in cotroller but I think it's not elegant.
EDIT.
Ok, Thansk for your help, but it's not working for me correctly.
I generate html like this:
<input type="hidden" value="96" name="Inputs[0].Key">
<input type="text" name="Inputs[0].Value">
In my controller I'm receiving this dictionary. The problem is that quantity of elements is correct, but all values are null. What is wrong here?
The best way to go about this is by using array-style model binding.
So, for each element you wish to name you create a hidden field to store the drop down value plus a text field to store the user-given name. You name them as follows:
<input type="hidden" name="element[0].Key" /><input type="text" name="name[0].Value" />
increasing the index value each time. This is easily achieved with a bit of JavaScript. You then create an action method which takes a KeyValuePair<string, string>[] as a parameter. You will then be able to parse through your values no problem with a loop or LINQ expression.
Use IEnumerable<KeyPairValue<string,string>> MySelectedItem = new List<KeyPairValue<string,string>>(); on model, and when adding it to the list, name it like an array:
MySelectedItem[1].Key, MySelectedItem[1].Value, MySelectedItem[2].Key...
(I haven't tested this, but it should work)
Edit: check out this blog post with better explanation on how to do it: http://haacked.com/archive/2008/10/23/model-binding-to-a-list.aspx
I am trying to find me feet with MVC4 Razor and I'm stuck with this simple problem.
When I use #Html.DisplayFor the model is always sent back as NULL, but when I use #Html.TextBoxFor this model is fully populated, what am I missing?
Thanks in advance
This is a common issue that many people miss in the asp.net mvc framework. Not just the difference in the helpers such as HiddenFor, DisplayFor, TextBoxFor - but how exactly the framework sets up automatically collecting and validating these inputs. The magic is all done with HTML5's data-* attributes. You will notice when looking at the input tag generated that there are going to be some extra properties in the form of data-val, data-val-required, and perhaps some additional data properties for types, for example numerics would be data-val-number.
These data attributes allow the jQuery extension jquery.validate.unobtrusive.js to parse the DOM and then decide which fields to validate or generate error messages.
The actual collection of posted data is reflected from the name property. This is what should map up to the model that is in the c# or vb [HttpPost] method.
Use HiddenFor when you want to provide posted data that the user does not need to be aware of.
Use DisplayFor when you want to show records but not allow them to be editted.
Use TextBoxFor when you want to allow user input or allow the user to edit a field.
EDIT
"the purpose of this view is to enable the user to view the data before submitting it to the database. Any ideas how I can achieve this?"
You could accomplish this with a duo of HiddenFor and DisplayFor. Use HiddenFor to have the values ready to be posted, and DisplayFor to show those values.
DisplayFor will not do the Model binding. TextBoxFor will do because it creates a input element in the form and the form can handle it when it is being posted. If you want to get some data in the HttpPost action and you dont want to use the TextBoxFor, you can keep that pirticulare model proeprty in a hidden variable inside the form using the HiddenFor HTML helper method like this.
#using(Html.BeginForm())
{
<p>The Type Name is</p> #Html.DisplayFor(x=>x.TypeName)
#Html.HiddenFor(x=>x.TypeName)
<input type="submit" value="Save" />
}
Use both DisplayFor and HiddenFor. DisplayFor simply displays the text and is not an input field, thus, it is not posted back. HiddenFor actually creates <input type="hidden" value="xxxx"/>
DisplayFor builds out a HTML label, not an input. Labels are not POSTed to the server, but inputs are.
I know this is a bit of an old question but you can roll your own, custom combined display control as shown below. This renders the model value followed by a hidden field for that value
#Html.DisplayExFor(model => Model.ItemCode)
Simply use what the framework already has in place
public static MvcHtmlString DisplayExFor<TModel, TProperty>(this HtmlHelper<TModel> htmlHelper, Expression<Func<TModel, TProperty>> ex)
{
var sb = new StringBuilder();
sb.Append(htmlHelper.DisplayFor(ex));
sb.Append(htmlHelper.HiddenFor(ex));
return MvcHtmlString.Create(sb.ToString());
}
Do you mean during a form post? If you use DisplayFor, this creates a element which does not contain any form values. Typically you use these in conjunction with each other to create a label for your textbox, then using the Html.TextBoxFor to allow users to modify the data element.
Example:
#Html.DisplayFor(x=>x.Item)
#Html.TextBoxFor(x=>x.Item)
Will Render
Item <a text input field following>
Or in HTML
<label for="Item">Item</label><input type="Text" id="Item" name="Item"/>
Say you create a form using ASP.NET MVC that has a dynamic number of form elements.
For instance, you need a checkbox for each product, and the number of products changes day by day.
How would you handle that form data being posted back to the controller? You can't set up parameters on the action method because you don't know how many form values are going to be coming back.
Just give each checkbox a unique name value:
<input class="approveCheck" id="<%= "approveCheck" + recordId %>"
name="<%= "approveCheck" + recordId %>" type="checkbox" />
Then parse the list of form values in the Action, after submit:
foreach (var key in Request.Form.Keys)
{
string keyString = key.ToString();
if (keyString.StartsWith("approveCheck", StringComparison.OrdinalIgnoreCase))
{
string recNum = keyString.Substring(12, keyString.Length - 12);
string approvedKey = Request.Form["approveCheck" + recNum];
bool approved = !String.IsNullOrEmpty(approvedKey);
// ...
You don't need to pass form values as arguments; you can just get them from Request.Form.
One other option: write a model binder to change the list into a custom type for form submission.
Per Craig's answer.. that is safer. There are quirks to posting multiple form elements with the same name. I would add that it would be wise to wrap the logic that makes the "collection" of controls in a way similar to WebForms. Web Forms prepend the container control's name and adds an index. For example, in a Repeater the form elements inside would be named (something like) RepeaterName_Element1, RepeaterName_Element2. When you go to get the elements out, you have to use FindControl or something of the sort.
Depending on the binders you are using, this should work:
<%var i = 0;
foreach (var product (IList<ProductSelection>)ViewData["products"]) {%>
<%=Html.Hidden(string.Format("products[{0}].Id", i), product.Id)%>
<%=Html.Checkbox(string.Format("products[{0}].Selected", i))%>
<%=product.Name%><br/>
<%}%>
...which will result in HTML something like this (notice the array notation on the names):
<input name="products[0].Id" type="hidden" value="123">
<input name="products[0].Selected" type="checkbox">
Widget
<input name="products[1].Id" type="hidden" value="987">
<input name="products[1].Selected" type="checkbox">
Gadget
...and the controller method that handles the post:
public ActionResult SelectProducts(IList<ProductSelection> products)
{
...
}
Upon binding, products parameter will contain two instances of ProductSelection.
One caveat is that I have not used the new default binding for complex objects. Rather I am using either the NameValueDeserializer or CastleBind, both from MvcContrib. They both behave this way. I am guessing binding in the Beta will work the same way.
Depending on your data, you could either output a 'CheckboxList' (which is not possible in the newer versions any more) and use a string[] parameter, or you could set up multiple forms and just modify the action.