I have a View that receives a List of an object and for each object in this list I generate a Partial View.
It's a seach result, such as Google. Each result will be wrapped in a form and each result will have its "save" post button.
So, when I post a form, I will lead user to another page where he will confirm the result he chose.
Some itens of the result I can save them to hidden fields and pass them in a FormCollection to this other page.
But, I was wondering if there's a way that I could pass this result object via post, in stead of creating hidden fields (?).
Thanks a lot!!
Hmmm, I think the answer is probably "no", but have a look at TempData and see if that might do the trick.
How about storing them in the database and assigning a resource identifier such as a GUID to the whole thing and only posting that?
You could write a custom serialize method in JS and then stuff the serialized object in a hidden field, like this:
<script type="text/javascript">
object; // from your search
var serialized = serialize(object);
$("#objectHidden").val(serialized);
</script>
Then on the ASP.NET MVC side, you would write a custom Deserialize() method and deserialize it into the object you want:
public ActionResult foo(FormCollection form)
{
MyObject object = MyObject.Deserialize(form["objectHidden"]);
}
This code is quick and dirty, but I hope it conveys the idea.
Related
i am teaching myself MVC and am struggling to work out the best solution to my problem. I have a search controller with a large amount of input fields. I will also have multiple overloads of the search fields eg basic search advanced search searchByCategory etc.
When the search form is posted i redirect to another action that displays the search results. If i press f5 the get action is fired again as opposed to the search results being refreshed in the action that my post redirects to. Ideally i would like to redirect to a search results Action Method without using the query string, or detect when refresh is hit and requery the database and just use different actions within the same search controller. I have read a lot of posts about this and the only 2 solutions i can find is using a session variable or TempData.Can anybody advise as to what is the best practice
From the Comments
Most of the time I prefer to use TempData in place of QueryString. This keeps the Url clean.
Question
Can anybody advise as to what is the best practice
Answer
Once the data is sent to Action Method to get the results from Database after then As per my knowledge you can use TempData to store the posted data. It is like a DataReader Class, once read, Data will be lost. So that stored data in TempData will become null.
var Value = TempData["keyName"] //Once read, data will be lost
So to persist the data even after the data is read you can Alive it like below
var Value = TempData["keyName"];
TempData.Keep(); //Data will not be lost for all Keys
TempData.Keep("keyName"); //Data will not be lost for this Key
TempData works in new Tabs/Windows also, like Session variable does.
You could use Session Variable also, Only major problem is that Session Variable are very heavy comparing with TempData. Finally you are able to keep the data across Controllers/Area also.
Hope this post will help you alot.
I think there is no need to even call Get Method after performing search although its good habit in case of if your are performing any add/update/delete operation in database. But in your case you can just return the View from your post method and no need to store data in tempdata or session until you really don't need them again. So do something like this:
[HttpPost]
public virtual ActionResult PerformSearch(SearchModel model)
{
// Your code to perform search
return View(model);
}
Hope this will help.
Hi thanks
I have had a chance to revisit this. the problem was i neglected to mention that i am using jQuery mobile which uses Ajax by default even for a normal Html.BeginForm. I was also returning a view which i have since learned will not updated the URL but only render new html for the current controller. my solution is to set the action, controller and html attributes in the Html.Beginformas follows :
#Html.BeginForm("Index", "SearchResults", FormMethod.Post, new { data_ajax = "false" })
inside the parameters for the index action of the searchResults controller I have a viewModel that represents the fieldset of the form that i am posting. The data-ajax="false" disables the Ajax on the form post and MVC takes care of matching the form post parameters to my model. This allows the url to update and when i press f5 to refresh the controller re-queries the database and updates the search results.
Thanks everybody for your help. I was aware of TempData but it is good to know that this is preferred over session data so i voted up your answer
In my ASP.NET MVC 3 app I have a page where, after its form is submitted I need to change a value from the form. If I do it in the ViewModel it has no effect, I have to do it use ModelState["Field"].Value.
The thing is that I actually have a lot of work I have to do on the ViewModel when the pages loads AND after the POST. So I have a method which receives the ViewModel and do all that work. But, as I said, after the POST, modifying the ViewModel object is useless. Why is that? The method on the controller is returning View(viewModel);. Shouldn't the view use the ViewModel values?
I'd like to understand why is useless to modify the ViewModel and also know if there is some method in the ModelState which "refresh" the fields values throw a ViewModel object.
Here is my controllers code:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Index(MyViewModel viewModel)
{
try
{
if (ModelState.IsValid)
//Do stuff and redirect
}
catch(Exception ex)
{
//Log and add error to the ModelState
}
someMethodWhichDoesALotOfThingsInTheViewModel(viewModel);
return View(viewModel);
}
I think the rest of the code is unnecessary, if anyone think it would help let me know!
Update
I don't want to lose any errors, not even those of the fields changed in the ViewModel. A good example would be a captcha, if the users makes any error in the form (only with the captcha field or only with any other fields and not with the captcha) I want to show him all his errors and also update the captcha. It makes no sense to render the form with the old captcha value inserted so I want to blank that field.
Update 2
I've opted to put #Value = Model.PropertyInViewModel in the HTML Attributes of each Html.TextBoxFor. But I'd prefer to avoid that nasty work so if someone comes out with any better solution please let me know.
The following will work:
ModelState.Remove("MyProperty");
viewModel.MyProperty = "new value";
You need to remove it from the model state because HTML helpers first look in there when binding their value.
All I could came out with is to add #Value = Model.PropertyInViewModel to each Html.TextBoxFor that is going to be modified in the ViewModel.
Another way, as #Darin Dimitrov said, would be to make my own helpers.
If you decide to remove modelstate values to prevent round-tripping take a look at this RemoveFor() extension method I made to remove ModelState errors without magic strings.
I have a controller post action that receives an IList<> as a parameter, and would like to iterate that list and TryUpdateModel for each item in the list. Like
[HttpPost]
public ActionResult SaveList(IList<Stuff> listOfStuff)
{
// Get existing list of Stuff objects
IList<Stuff> currentStuff = db.GetStuffList();
// iterate over list of Stuff
foreach (Stuff stuff in listOfStuff)
{
// I'd like to do something akin to this
TryUpdateModel(currentStuff[correspondingItem_to_stuff], stuff);
}
As you can see, I would like to be able to TryUpdateModel against each item in listOfStuff, but there is no direct way to make that call with the two Stuff objects. What is the best way of accomplishing this?
Thanks
If you want currentStuff to be the same as list of stuff you just have to UpdateModel(currentStuff). UpdateModel is for copying posted http request related values values into an object and not for copying the properties of two objects.
UpdateModel and TryUpdateModel must receive a type of ValueProvider (a FormCollection for example). validate the posted object in your controller or service layer and then let your DB layer handle the add/update by using attach() or applycurrentvalues() (if your using Entity Framework for example)
It looks like this is not supported directly. After some more searching I found a couple of links, the most useful of which was
Passing Controller a FormCollection and an IList
This post has a couple of other useful links in it. I ended up rolling it myself unfortunately, and using TempData as detailed here to recover in the case where saving the form data fails.
I am new to ASP.NET MVC, particularly ajax operations. I have a form with a jquery dialog for adding items to a drop-down list. This posts to the controller action.
If nothing (ie void method) is returned from the Controller Action the page returns having updated the database, but obviously there no chnage to the form. What would be the best practice in updating the drop down list with the added id/value and selecting the item.
I think my options are:
1) Construct and return the html manually that makes up the new <select> tag
[this would be easy enough and work, but seems like I am missing something]
2) Use some kind of "helper" to construct the new html
[This seems to make sense]
3) Only return the id/value and add this to the list and select the item
[This seems like an overkill considering the item needs to be placed in the correct order etc]
4) Use some kind of Partial View
[Does this mean creating additional forms within ascx controls? not sure how this would effect submitting the main form its on? Also unless this is reusable by passing in parameters(not sure how thats done) maybe 2 is the option?]
UPDATE:
Having looked around a bit, it seems that generating html withing the controller is not a good idea. I have seen other posts that render partialviews to strings which I guess is what I need and separates concerns (since the html bits are in the ascx). Any comments on whether that is good practice.
look at the ContentResult you can specify the mime type of what you return (text/html)
You could alternatively make a control that take a IEnumerable of whatever you put in the selectlist, and build it using the view engine. That way you keep the formatting of the html (in this case a list of options) into a view, and not in your code.
<%# Control Language="C#"Inherits="System.Web.Mvc.ViewUserControl<IEnumerable<Article>>"%>
<%foreach (var article in Model){%>
<option><%:article.Title %></option>
<%} %>
I think I would go for that second one
From what I understood, the jQuery dialog contains a form that, when submitted, will post to an action which updates the database with some information. You want to get the newly added database information and update the same form that was used to trigger the database update.
If that is the case, then I think the best clean and logical option is to return JSON serialization of the items to be put in the drop down right after you update the database. Then, using jQuery, you would clear the drop down and append option tags into it.
You can also write a new, seperate action that returns the JSON serialization of the database objects you need. You would have jQuery call another post to this action as a callback to your first ajax post (the one used to update the database).
Here is a quick snippet
public ActionResult UpdateDatabase(string something)
{
/// update the database
IEnumerable<Items> items = getItemsFromDatabase(); // or w/e
var vals = items.Select(x=> new { value = x.ID, text = x.Name }); // something similar
return Json(vals);
}
Personally, I would write a separate function that returns JSON. This ensure separation of concerns, and gives me a function I can use in many different places.
Returning a JsonResult with all the items is the most versatile and least-bandwidth intensive solution as long as you are happy to iterate through the list in jQuery and update your drop-down list.
Using a partial view is nice for HTML that you can .load(...) directly into your select, but less versatile.
I would go with the JsonResult.
In your Controller:
public JsonResult UpdateItem(string sItem)
{
// 1. Insert new item into database if not exist...
// {update code here}
// 2. retrieve items from database:
IEnumerable<Item> Items = GetItems();
// 3. return enumerable list in JSON format:
return new JsonResult{ Data = new {Items = Items, Result = "OK" }};
}
On client-side:
Iterate through Items array and add the items to your list.
Short: how does modelbinding pass objects from view to controller?
Long:
First, based on the parameters given by the user through a search form, some objects are retrieved from the database.
These objects are given meta data that are visible(but not defining) to the customer (e.g: naming and pricing of the objects differ from region to region).
Later on in the site, the user can click links that should show details of these objects.
Because these meta data are important for displaying, but not defining, I need to get the previously altered object back in the controller.
When I use the default asp.net mvc modelbinding, the .ToString() method is used. This off course doesn't return a relevant string for recreating the complete object.
I would have figured the ISerializable interface would be involved, but this is not so.
How should I go about to get the desired effect? I can't imagine I'm the first one to be faced with this question, so I guess I'm missing something somewhere...
The default model binding takes form parameters by name and matches them up with the properties of the type specified in the argument list. For example, your model has properties "Price" and "Name", then the form would need to contain inputs with ids/names "Price" and "Name" (I suspect it does a case insensitive match). The binder uses reflection to convert the form values associated with these keys into the appropriate type and assigns it to the properties of a newly created object of the type specified by the parameter (again derived by reflection).
You can actually look at (and download) the source for this at http://www.codeplex.com/aspnet, although you'll have to drill down into the MVC source from there. I'd give a link to the DefaultModelBinder source, but the way they are constructed, I believe the link changes as revisions are introduced.
So, to answer your question, you need to have parameters (could be hidden) on your form that correspond to the properties of the object that you want to recreate. When you POST the form (in the view) to the controller, the binder should reconstitute an object of the specified type using the form parameters. If you need to do translation from the values in the form parameter to the object properties, you'll probably need to implement your own custom model binder.
[EDIT] In response to your second post:
Let's say that we want to have a link back to an action that uses a customized object. We can store the customized object in TempData (or the Session if we need it to last more through more than one postback) with a particular key. We can then construct the action link and provide the key of the object as value to the ActionLink in an anonymous class. This will pass back the key as a Request parameter. In our action we can use the key from this parameter to retrieve the object from TempData.
<%= Html.ActionLink( ViewData["CustomObject1",
"Select",
new { TempDataKey = ViewData["CustomObject1_Key"] }
) %>
public ActionResult Select()
{
Entity custObj = null;
string objKey = Request.Params["TempDataKey"];
if (!string.IsNullOrEmpty(objKey))
{
custObj = (Entity)TempData[objKey];
}
... continue processing
}
#tvanfosson
Thanks for your explanation, but what about links? (no forms involved)
Currently the Html.ActionLink(c=>c.Action(parameter), "label") takes objects as parameter. These have to be translated into URL parts. For this, MVC ALWAYS goes to the .ToString() method. I don't want to serialize my object in the ToString method.
Shouldn't I be able to somehow help the framework serialize my object? Say through the ISerialize interface or something?