This post walks you through creating a UI for paging, sorting and filtering a list of data items. It makes use of the excellent MVCContrib Grid and Pager Html UI helpers. A sample project is attached at the bottom. Our UI will eventually look like this. The application will make use of the Northwind database. The top portion of the page has a filter area region. The filter region is enclosed in a form tag. The select lists are wired up with jQuery
to auto post back the form. The page has a pager region at the top and bottom of the product list. The product list has a link
to display more details about a given product. The column headings are clickable for sorting and an icon shows the sort direction. Strongly Typed View Models The views are written
to expect strongly typed objects. We suffix these strongly typed objects with ViewModel since they are designed specifically for passing data down
to the view. The following listing shows the ProductViewModel. This class will be used
to hold information about a Product. We use attributes
to specify if the property should be hidden and what its heading in the table should be. This metadata will be used by the MvcContrib Grid
to render the table. Some of the properties are hidden from the UI ([ScaffoldColumn(false)) but are needed because we will be using those for filtering when writing our
LINQ query. public ActionResult Index(
string productName,
int? supplierID,
int? categoryID,
GridSortOptions gridSortOptions,
int? page)
{
var productList = productRepository.GetProductsProjected();
// Set default sort column
if (string.IsNullOrWhiteSpace(gridSortOptions.Column))
{
gridSortOptions.Column = "ProductID";
}
// Filter on SupplierID
if (supplierID.HasValue)
{
productList = productList.Where(a => a.SupplierID == supplierID);
}
// Filter on CategoryID
if (categoryID.HasValue)
{
productList = productList.Where(a => a.CategoryID == categoryID);
}
// Filter on ProductName
if (!string.IsNullOrWhiteSpace(productName))
{
productList = productList.Where(a => a.ProductName.Contains(productName));
}
// Create all filter data and set current values if any
// These values will be used
to set the state of the select list and textbox
// by sending it back
to the view.
var productFilterViewModel = new ProductFilterViewModel();
productFilterViewModel.SelectedCategoryID = categoryID ?? -1;
productFilterViewModel.SelectedSupplierID = supplierID ?? -1;
productFilterViewModel.Fill();
// Order and page the product list
var productPagedList = productList
.OrderBy(gridSortOptions.Column, gridSortOptions.Direction)
.AsPagination(page ?? 1, 10);
var productListContainer = new ProductListContainerViewModel
{
ProductPagedList = productPagedList,
ProductFilterViewModel = productFilterViewModel,
GridSortOptions = gridSortOptions
};
return View(productListContainer);
}
The following diagram shows the rest of the key ViewModels in our design.
We have a container class called ProductListContainerViewModel which has nested classes.
The ProductPagedList is of type IPagination<ProductViewModel>. The MvcContrib expects the IPagination<T> interface
to determine the page number and page size of the collection we are working with. You convert any IEnumerable<T> into an IPagination<T> by calling the AsPagination extension method in the MvcContrib library. It also creates a paged set of type ProductViewModel.
The ProductFilterViewModel class will hold information about the different select lists and the ProductName being searched on. It will also hold state of any previously selected item in the lists and the previous search criteria (you will recall that this type of state information was stored in Viewstate when working with WebForms). With MVC there is no state storage and so all state has
to be fetched and passed back
to the view.
The GridSortOptions is a type defined in the MvcContrib library and is used by the Grid
to determine the current column being sorted on and the current sort direction.
The following shows the view and partial views used
to render our UI. The Index view expects a type ProductListContainerViewModel which we described earlier.
<%Html.RenderPartial("SearchFilters", Model.ProductFilterViewModel); %>
<% Html.RenderPartial("Pager", Model.ProductPagedList); %>
<% Html.RenderPartial("SearchResults", Model); %>
<% Html.RenderPartial("Pager", Model.ProductPagedList); %>
The View contains a partial view “SearchFilters” and passes it the ProductViewFilterContainer. The SearchFilter uses this Model
to render all the search lists and textbox.
The partial view “Pager” uses the ProductPageList which implements the interface IPagination. The “Pager” view contains the MvcContrib Pager helper used
to render the paging information. This view is repeated twice since we want the pager UI
to be available at the top and bottom of the product list. The Pager partial view is located in the Shared directory so that it can be reused across Views.
The partial view “SearchResults” uses the ProductListContainer model. This partial view contains the MvcContrib Grid which needs both the ProdctPagedList and GridSortOptions
to render itself.
The Controller Action
An example of a request like this: /Products?productName=test&supplierId=29&categoryId=4. The application receives this GET request and maps it
to the Index method of the ProductController.
Within the action we create an IQueryable<ProductViewModel> by calling the GetProductsProjected() method.
/// <summary>
/// This method takes in a filter list, paging/sort options and applies
/// them
to an IQueryable of type ProductViewModel
/// </summary>
/// <returns>
/// The return object is a container that holds the sorted/paged list,
/// state for the fiters and state about the current sorted column
/// </returns>
public ActionResult Index(
string productName,
int? supplierID,
int? categoryID,
GridSortOptions gridSortOptions,
int? page)
{
var productList = productRepository.GetProductsProjected();
// Set default sort column
if (string.IsNullOrWhiteSpace(gridSortOptions.Column))
{
gridSortOptions.Column = "ProductID";
}
// Filter on SupplierID
if (supplierID.HasValue)
{
productList.Where(a => a.SupplierID == supplierID);
}
// Filter on CategoryID
if (categoryID.HasValue)
{
productList = productList.Where(a => a.CategoryID == categoryID);
}
// Filter on ProductName
if (!string.IsNullOrWhiteSpace(productName))
{
productList = productList.Where(a => a.ProductName.Contains(productName));
}
// Create all filter data and set current values if any
// These values will be used
to set the state of the select list and textbox
// by sending it back
to the view.
var productFilterViewModel = new ProductFilterViewModel();
productFilterViewModel.SelectedCategoryID = categoryID ?? -1;
productFilterViewModel.SelectedSupplierID = supplierID ?? -1;
productFilterViewModel.Fill();
// Order and page the product list
var productPagedList = productList
.OrderBy(gridSortOptions.Column, gridSortOptions.Direction)
.AsPagination(page ?? 1, 10);
var productListContainer = new ProductListContainerViewModel
{
ProductPagedList = productPagedList,
ProductFilterViewModel = productFilterViewModel,
GridSortOptions = gridSortOptions
};
return View(productListContainer);
}
The supplier, category and productname filters are applied
to this IQueryable if any are present in the request. The ProductPagedList class is created by applying a sort order and calling the AsPagination method. Finally the ProductListContainerViewModel class is created and returned
to the view.
You have seen how
to use strongly typed views with the MvcContrib Grid and Pager
to render a clean lightweight UI with strongly typed views. You also saw how
to use partial views
to get data from the strongly typed model passed
to it from the parent view. The code also shows you how
to use jQuery
to auto post back.
The sample is attached below. Don’t forget
to change your connection string
to point
to the server containing the Northwind database.
NorthwindSales_MvcContrib.zip
My name is Kobayashi. I work for Keyser Soze.
