Pagination

(formerly https://code.google.com/p/source-pagination/)

Pagination allows easy control and deferred execution of specific pages in a LINQ request.

First, we'll create a model that extends Pagination.Models.PageRequestModel. Extending this class gives our model properties like RequestedPage (the page index requested by the user) and ItemsPerPage (the number of items to show per page). Our model will also inherit the method GetRequestValues, which can serialize the simple properties of the model to an IDictionary<string, object> of key-value pairs.

This model adds a single property, SearchText.

public class SearchModel : Pagination.Models.PageRequestModel {
    public string SearchText { get; set; }
}

Next, we'll create a simple data set of strings. In real life, this IQueryable<string> could come from a database through an ORM like EntityFramework. For simplicity's sake, though, we'll get a collection of all the types loaded in our application.

var types = AppDomain.CurrentDomain.GetAssemblies()
    .SelectMany(s => s.GetTypes())
    .Select(t => t.FullName)
    .AsQueryable();

Now let's make an instance of our model (again, in real life this instance could come from an MVC controller action parameter). Then we apply a Where clause to our data set according to it's SearchText value.

var model = new SearchModel { SearchText = 'Mvc' };
var searchText = model.SearchText;
if (!string.IsNullOrWhiteSpace(searchText)) types = types.Where(t => t.Contains(searchText));

We can use a Pagination.PageSourceFactory to create a Pagination.Models.IPageSourceModel. This is the object that will do the grunt work of paging the results of the request.

var factory = new Pagination.PageSourceFactory {
    MaxItemsPerPage = 50,
    DefaultItemsPerPage = 20
};
var source = factory.CreateSource(types, model);

Now we can get to work. The results object has properties like TotalPageCount (the total number of pages available to the query) and TotalItemCount (the total number of items on all pages in the query). The Results property is an IQueryable representing the actual items on the requested page.

var results = Model.OrderBy(s => s).Query();
var items = results.Results.Select(r => new { TypeName = r });

To create a collection of Pagination.Models.IPageLinkModel (a class that can be used to create an HTML link to a specific page in the request), use the LinkPages method.

var pages = results.LinkPages(PageLinker.CreateDynamic(true, "←", "→"));

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