I'm making the transition from webforms to MVC (I know, 3 years late) and I "get it" for the most part, but there's a few things I'd like advice and clarification on:
First off, what happens if you want to dynamically add inputs to a view? for example, in an old webform for generating invoices I had a button with a server-side click event handler that added an extra 5 invoice item rows. The stateful nature of webforms meant the server handled the POST event "safely" without altering the rest of the page.
In MVC I can't think how I'd do this without using client-side scripting (not a showstopper, but I would like to support clients that don't have scripting enabled).
The second problem relates to the invoices example. If my Model has a List, how should I be generating inputs for it?
I know data binding is a possible solution, but I dint like surrendering control.
Finally, back to the "stateful pages" concept - say I've got a Dashboard page that has a calendar on it (I wrote my own calendar Control class, the control itself is stateless, but can use the webform viewstate to store paging information) - how could a user page through the calendar months? Obviously POST is inappropriate, so it would have to be with GET with a querystring parameter - how can I do this in MVC? (don't say AJAX).
Thanks!
In MVC you design your actions to accommodate your needs. For example, if you wanted to be able to add 5 rows to an invoice NOT using client-side scripting, you'd probably have your GET action for the invoice generation take a nullable int parameter for the number of rows. Store the current number of rows in the view model for the page and generate a link on the page to your GET action that has the parameter value set to 5 more than the current value. The user clicks the link and the GET view generates the page with the requested number of rows.
Controller
[HttpGet]
public ActionResult Invoice( int? rows )
{
rows = rows ?? 5; // probably you'd pull the default from a configuration
...
viewModel.CurrentRows = rows;
return View( viewModel );
}
View
#Html.ActionLink( "Add 5 Lines", "invoice", new { rows = Model.CurrentRows + 5 }, new { #class = "add-rows" } )
You would probably also add some script to the page that intercepts the click handler and does the same thing via the script that your action would do so that in the general case the user doesn't have to do a round trip to the server.
<script type="text/javascript">
$(function() {
$('.add-rows').click( function() {
...add additional inputs to the invoice...
return false; // abort the request
});
});
</script>
Likewise for your calendar. The general idea is you put enough information in your view model to generate all the actions that you want to perform from your view. Construct the links or forms (yes you can have multiple forms!) in your view to do the action. Use parameters to communicate to the controller/action what needs to be done. In the rare case where you need to retain state between actions, say when performing a wizard that takes multiple actions, you can store the information in the session or use TempData (which uses the session).
For things like a calendar you'd need the current date and the current view type (month/day/year). From that you can construct an action that takes you to the next month/day/year. For a paged list you need the current page, the current sort column and direction, the number of items per page, and the number of pages. Using this information you can construct your paging links that call back to actions expecting those parameters which simply do the right thing for the parameters with which they are called.
Lastly, don't fear AJAX, embrace it. It's not always appropriate (you can't upload files with it, for example), but your users will appreciate an AJAX-enabled interface.
In MVC you can store application state in various ways. In your controller you have direct access to the Session object and you can also store state to the database.
your view can contain basic control flow logic, so, if your model has a list you can iterate over it in the view and, for example, render an input control for each item in the list. you could also set a variable in a model to be the maximum number of rows on the viewpage and then render a row in a table for the number specified by the model.
paging is basically the same thing. you can create a partial view (user control in the webform world) that shows page numbers as links, where each link calls an action that fetches the data for that page of results.
i'm not sure what your beef is with ajax or javascript
Related
I have cascading dropdowns in my MVC partial view. DD1 drives the values in DD2. When I select DD1 I want DD2 to be populated with, based on a DB table, the correct values based on DD1's value.
My thought was to make DD2 a partial view and nest in my form. Then, with ajax, I can tell the partial view to refresh and pass it the value of DD1.
The problem is, when I submit the whole view (with both DD1 and DD2 and a bucnh of other stuff, how do I get the value that is in DD2?
I'm trying to solve this problem using MVC, rather than triggering a javascript function on change of DD1 to make a JSON call to get the options and then using javascript to modify DD2 to the correct values.
How should I do this?
How big are your value sets for each drop down?
I was attempting to do this same thing a few years ago. DD1 was United States and Canada, and DD2 was the associated States and Provinces. If your data set is relatively small, you're better off just putting all the select list markup for both cases in the page, and then swapping it out with javascript (jQuery). You'll be saving yourself the request round trip, regardless of whether you go ajax or a full page refresh.
If the data set is large and it doesn't make sense to put all values in the markup, and you want to use MVC views instead of modifying the DOM with an ajax call, then just refresh the entire page. If you want to go ajax, then just modify the DOM with jQuery; you don't need a partial view to accomplish this.
You are going to have to use javascript unless you want to do an entire page postback. For this type of thing, javascript/ajax is the way to go. I personally had a hard time when I switched to MVC having to accept that all this business logic was happening outside of the MVC model. But in the end, it's whatever makes the website work best (user doesn't see your code and know how pretty it is).
Anyway, partials won't work either unless you post the whole page since without using javascript, the partial is rendered as part of that page/form.
I would just add a onchange event to the first dropdown that triggers a json call to a method in the same controller...something like
...jquery...
$("#mydropdown").change(function() {
$.post("/Controller/DropdownChangedJSON", { firstdropdownvalue: $("#mydropdown").val() }, function(data) {
$("#seconddropdown").empty();
// loop through "data" to populate dropdown
}); //post
}); //mydropdown_change()
and in your controller:
public JsonResult DropdownChangedJSON(string firstdropdownvalue) {
//get results
List<datamodel> myarray = //something
return new JsonResult { Data = new { success = true, rows = myarray } };
}
hope this helps
I have a model that looks like this:
Business
- Branch
- Phone(*)
- Phone Type
- Number
- Opening hours (*)
- Days in week
- Working period (*)
- From time
- To time
- Custom field (*)
- Name
- Value
- Address
- Address line
- City
- State
- Zip
- Yada yada
I created Editor Templates for each of the class types above.
I want to have a common Business editor template with a submit form that posts the entire structure to a single action and saves it, both for an existing or new entity.
Is Editor Templates the right approach? How do I submit the form along its entire downline?
How do I make Add and Remove buttons to add/remove phone numbers within the form?
How do I order items in the collection (i.e. I want to have arrows near each phone number so the user can move it up or down in the client list, then handle the saving on server, for that I already have the solution).
Bottom line, my issue is how to get the right values posted back to the server, and how to modify the inner collections on the client. Once the proper data is on the server in this way or another I'll know how to deal with it. My problem is the client side and the correct way of data submission.
Update
I saw this answer, which basically answers the 1st part of my question, tho the latter two still remain (add-remove-order buttons - manage collections on client).
My problem is not how to add/remove/reorder rows at the client's DOM, but how to modify the client data and then receive it in the server in the action the looks like this:
[HttpPost]
public ActionResult Save(Business business)
{
/// blah blah
}
Update
Here is how I try to shove in the new data:
View:
#Ajax.ActionLink("Add", "AddCustomField", new AjaxOptions { UpdateTargetId = "customFields", InsertionMode = InsertionMode.InsertAfter })
Action:
public PartialViewResult AddOpeningTimes()
{
var ot = new OpeningTimes();
ot.WorkingPeriods.Add(new WorkingPeriod());
var e = EditorFor(ot);
//just here for debugging, the values are both empty strings
e.ViewData.TemplateInfo.HtmlFieldPrefix = ViewData.TemplateInfo.HtmlFieldPrefix;
return e;
}
//this method is on the base controller:
protected PartialViewResult EditorFor<TModel>(TModel model)
{
return PartialView("EditorTemplates/" + typeof(TModel).Name, model);
}
The thing is the name for the appropriate fields are not enumerated as needed (Branches[0].CustomField[0].Key), instead, it's just Key.
As far as i know, there is no 'simple' way to do this.
Add button - you have to wire javascript that creates a part of form (eg. phone type select and phone text box) and set its id/name. Basically you find the last item in the form, which will have name of Phone[x].PhoneType, and set the values on new part of form to appropriate values with x + 1.
An option to avoid generating the part the form by yourself is to create a hidden 'template' and copy that. Then change id and name.
Remove button - if you simply deleted items from DOM, you would create gaps in the sequence and MVC doesn't know how to deal with that. One possible approach is to mark items in the form as deleted using a hidden field, then handling that on the server.
Reordering - I would add a property called Order to whatever needs this feature, then render it as hidden and change using javascript when reordering. You also have to set it appropriately when adding an item.
Useful properties in these situations are also: IsNew, IsUpdated - along with IsDeleted allow for relatively easy processing on the server.
Of course, if you have nested collections each needing add/remove/reorder functionality it will be kind of difficult to do and debug.
UPDATE
The action rendering the partial view can't know what the html prefix should be, because it doesn't have the context (that the parent is Branch object etc.).
If you want to use AJAX, i would recommend sending the html field prefix as a parameter (public PartialViewResult AddOpeningTimes(string htmlPrefix)). htmlPrefix could be Branches[0].CustomField[last_custom_field + 1].. It's probably the cleanest way to achieve what you want, even if it's in fact not very clean.
What is the best ASP.NET MVC pattern for paging data when the data is filtered by form criteria?
This question is similar to: Preserve data in .net mvc but surely there is a better answer?
Currently, when I click the search button this action is called:
[AcceptVerbs(HttpVerbs.Post)]
public ActionResult Search(MemberSearchForm formSp, int? pageIndex, string sortExpression)
{}
That is perfect for the initial display of the results in the table.
But I want to have page number links or sort expression links re-post the current form data (the user entered it the first time - persisted because it is returned as viewdata), along with extra route params 'pageIndex' or 'sortExpression',
Can an ActionLink or RouteLink (which I would use for page numbers) post the form to the url they specify?
<%= Html.RouteLink("page 2", "MemberSearch", new { pageIndex = 1 })%>
At the moment they just do a basic redirect and do not post the form values so the search page loads fresh.
In regular old web forms I used to persist the search params (MemberSearchForm) in the ViewState and have a GridView paging or sorting event reuse it.
One possible solution is to attach a javascript click handler to the pager links that will submit the form by updating a hidden field containing the page number. This way you will get all the search criteria in the controller action.
Another possibility is to transform those pager links into submit buttons and place them inside the form.
A third possibility is to use the Session to persist search criteria.
You could perform a GET instead of a POST. if your request is to return search results, a GET might make more sense anyway. The benifit would be that all of your search fields are encoded into the URL. So, when you perform a page or sort on th exisiting URL, your data is perserved.
I have an example that using the MvcContrib Grid and Pager here:
http://weblogs.asp.net/rajbk/archive/2010/05/08/asp-net-mvc-paging-sorting-filtering-using-the-mvccontrib-grid-and-pager.aspx
You may thick that it is a silly question but I am confused!
I have a situation that I have a Lecture table.
And I want to store attendance of who have registered for it.
I have master table of People who will register, lecture table, and Important one table is attendance that stores P.k. as f.k. of rest of the table.
On Index view of lecture operator will select Attendance and enter attendance information.
My problem It show only one page for attendance entry and that page can also open open in EDIT mode, for editing attendance.
So what would be the design of the page and process flow of taking attendance?
Some of the ways:
You can use same page for editing and listing if you define block where are you rendering partial/dynamic block(user control). You need to extend HtmlHelper so you can pass name of a UserControl and you have to from controller pass to view(with ViewData) name of user control you want rendered. This way you can use same template(View/Page) with different actions and different response.
You can have editing on client. You can use jQuery UI library to popup dialog box for editing. For posting editing information back, you can use jquery .ajax method. As things happening on client and you request different actions on controller, it doesn't matter how you will approach this in design sense. You can use dialogs, you can transform existing elements on page etc.
Hope this helps
I have two forms on one page: a results form and a search form. The search form uses a partial view because it is displayed on several different pages. I want to be able to persist the data in the search form regardles of which button on which form the user clicks. The problem is that when the user clicks on a link or button from the results form, only the form values from the results form are posted, the values from the search form are not included. How can I maintain the values in the search form even when it is not the form that is submitted? I do not want to use any type of session state to maintain the form and I dont want to write the search values in hidden fields in the results form. I just want to be able to post them with the form values of the results form so that the users search criteria can be maintained accross any page that displays the search partial view. What am I missing?
The first thought that occured to me is to remove the form wrapping the search control and just let it be rendered into the form with the results data. I worry here about naming conflicts. What happens when the search from has a control with the same name as the results form, wouldn't this cause a naming conflict? I suppose that this could just be managed manually to ensure that there are unique names whenever rendering partial views into other views, perhaps even going so far as to prefix values with the partial view name, but that reminds me of the ugliness that is INamingContainer in web forms - plus makes for cumbersome field names in your model.
Is there some sort of elegant solution that will allow a form to persist state that I am missing? Thanks!
Normally, I persist the search criteria on the server side when the search is performed. If the user changes the search criteria after performing the search, then posts the form any changes are, of course, lost but that's arguably correct behavior since the search wasn't invoked. This is true whether the search is performed from a full post or via ajax. Handling it this way keeps the actions cleaner, I think as you don't need to handle the search data in the other actions.
If you absolutely need to have the search parameters included, you could consider having the second form post via javascript, pick up the search field values dynamically and add them to the second form (as hidden fields) prior to posting the second form. You wouldn't have to maintain the values in two places in synchronization, but you would have to copy them to the second form before posting.
At the moment i got it like this:
Forms which has search box, posts query (and additional data if needed) to search controller which then renders search view. Search view is made from search box and search results partial views. During this - search box form is reconstructed by posted data.
If i need search results form to perform another search request (for example, with specified page index), it goes through ajax, which posts search box form + page index from search results form. Take a look here for ideas (update that JS method with targetId parameter for updating specified div/form and post additional data if needed here like this:
form.serialize()+"&pageIndex=5"
In short: if you need to maintain state of form + update another in one page - consider using partial updates, otherwise you will end up inventing ViewState 2.0.
One caveat with this way - it's tricky to make search box contain something what is related with search results (i.e. - total count of found items). Before i managed to handle this, our designer did that - i just need to add div with appropriate class name ("sbsubst" or something) and it looks that it's inside search box. :)
When you have few forms at your page each form sends only its own data. In WebForms you had only one form (at least server-side) and each control was included into this form. In ASP.NET MVC you can use the same scenario and I'm afraid you will have to if you want to have the described behavior. Don't forget - partial forms don't have to be real forms. Moreover, RenderPartial is mostly used for "control-like" layout creation.
As for the second part of your question I would suggest naming your text boxes in search form with some normal prefix like "search" or something like that. For instance, if you have text box "text" and "language" in the form, you will have "searchText" and "searchLanguage". These names are quite unique and you will have normal names in your parameters.
I am not suggesting you populating the hidden values in your results form on POST event since you said it's not an option for you but still it may be the only way if you want to have two forms.
I think the best approach will be storing the text from search input when it changes in the query part of your second form action url. For example (not tested):
$('input#yourSearchInput').change(function()
{
var searchText = $(this).val();
// or? var searchText = encodeURIComponent($(this).val());
var secondForm = $('form#secondFormId');
var action = secondForm.attr('action');
var queryStart = action.lastIndexOf('?search=');
if(queryStart > -1) {
action = action.substring(1, queryStart);
}
action = action + "?search=" + searchText;
secondForm.attr('action', action);
});
In Controller (or custom filter):
protected override void OnActionExecuting(ActionExecutingContext filterContext)
{
var search = Request.QueryString["search"];
if(!String.IsNullOrEmpty(search)) {
ViewData["SearchFromPOST"] = search;
}
base.OnActionExecuting(filterContext);
}
In your Search Control:
<%= TextBox("yourSearchInputId", ViewData["SearchFromPOST"]) %>