Skip to main content

A DD4T.net Implementation - Pagination (Views)

In previous post Pagination (Models), I presented a way of modeling the server-side code to display dynamic lists of Dynamic Component Presentations (DCP) using AJAX.

In this post, I present the server-side view logic in context of MVC .net architecture and using Razor CSHTML views.

As presented in the previous post, the Controller creates a model class that contains the paginated list, and it then attaches this model to the ViewBag. In the example it was DeviceController, that created model DocumentPartial which contained a paginated list of documents.

We now need to display this list of paginated items in a Razor view. In order to make the logic reusable and succinct, I implemented the paginated view as partial view. The Component view corresponding to the controller includes the partial view and passes to it the model previously saved in the ViewBag. This makes the partial view generic and reusable from other contexts.

To continue our earlier example, the view corresponding to DeviceController is Device.cshtml and contains roughly the code below. The idea is to first check wether the ViewBag contains our model and if so, then call the partial view _PartialDocument.cshtml with the DocumentPartial model.

@model Device

<!-- markup goes here -->

@if (ViewBag.DocumentPartial != null)
{
    @Html.Partial("_PartialDocument", (DocumentPartial)ViewBag.DocumentPartial)
}

<!-- more markup here -->

The main view logic is contained in the partial view. In our example, _PartialDocument.cshtml, processes the PagedItems property and displays the items in that list according to some input parameters. The input parameters can be the current page to display (the page number) or the page size (the number of items per page). Additionally, the partial view displays some kind of page iterator that allows for navigation between pages of items (such as next page, previous page, or jumping to a specific page number). The outline of the Razor partial code is shown below:

@model DocumentPartial
@using PagedList.Mvc;

<div class="paged-section">
    Viewing @Model.PagedItems.Count of @Model.PagedItems.TotalItemCount documents

    @if (Model.IsPostback)
    {
        foreach (Asset asset in Model.PagedItems)
        {
            //Display logic goes here
        }

        <div>
            Page @(Model.PagedItems.PageCount < Model.PagedItems.PageNumber ?
                0 : Model.PagedItems.PageNumber)
            of @Model.PagedItems.PageCount
        </div>

        @Html.PagedListPager(Model.PagedItems, pageNumber => Model.GetPagerUrl(pageNumber))
    }
</div>

Note the usage of the Html.PagedListPager -- this extension method provided by PagedList.Mvc will generate a page iterator similar to the one below:

<div class="pagination-container">
    <ul class="pagination">
        <li class="active"><a>1</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/2.ajax">2</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/3.ajax">3</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/4.ajax">4</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/5.ajax">5</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/6.ajax">6</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/7.ajax">7</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/8.ajax">8</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/9.ajax">9</a></li>
        <li><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/10.ajax">10</a></li>
        <li class="disabled PagedList-ellipses"><a>&#8230;</a></li>
        <li class="PagedList-skipToNext"><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/2.ajax" rel="next">»</a></li>
        <li class="PagedList-skipToLast"><a href="http://my.server.com/Device/Index/123/456/Device/_PartialDocument/23.ajax">»»</a></li>
    </ul>
</div>

In the next post Pagination (AJAX), I present the client-side Javascript solution that calls these server-side components and that completes the pagination topic.


Comments

Popular posts from this blog

Toolkit - Dynamic Content Queries

This post if part of a series about the  File System Toolkit  - a custom content delivery API for SDL Tridion. This post presents the Dynamic Content Query capability. The requirements for the Toolkit API are that it should be able to provide CustomMeta queries, pagination, and sorting -- all on the file system, without the use third party tools (database, search engines, indexers, etc). Therefore I had to implement a simple database engine and indexer -- which is described in more detail in post Writing My Own Database Engine . The querying logic does not make use of cache. This means the query logic is executed every time. When models are requested, the models are however retrieved using the ModelFactory and those are cached. Query Class This is the main class for dynamic content queries. It is the entry point into the execution logic of a query. The class takes as parameter a Criterion (presented below) which triggers the execution of query in all sub-criteria of a Criterio

A DD4T.net Implementation - Custom Binary Publisher

The default way to publish binaries in DD4T is implemented in class DD4T.Templates.Base.Utils.BinaryPublisher and uses method RenderedItem.AddBinary(Component) . This produces binaries that have their TCM URI as suffix in their filename. In my recent project, we had a requirement that binary file names should be clean (without the TCM URI suffix). Therefore, it was time to modify the way DD4T was publishing binaries. The method in charge with publishing binaries is called PublishItem and is defined in class BinaryPublisher . I therefore extended the BinaryPublisher and overrode method PublishItem. public class CustomBinaryPublisher : BinaryPublisher { private Template currentTemplate; private TcmUri structureGroupUri; In its simplest form, method PublishItem just takes the item and passes it to the AddBinary. In order to accomplish the requirement, we must specify a filename while publishing. This is the file name part of the binary path of Component.BinaryConten

Scaling Policies

This post is part of a bigger topic Autoscaling Publishers in AWS . In a previous post we talked about the Auto Scaling Groups , but we didn't go into details on the Scaling Policies. This is the purpose of this blog post. As defined earlier, the Scaling Policies define the rules according to which the group size is increased or decreased. These rules are based on instance metrics (e.g. CPU), CloudWatch custom metrics, or even CloudWatch alarms and their states and values. We defined a Scaling Policy with Steps, called 'increase_group_size', which is triggered first by the CloudWatch Alarm 'Publish_Alarm' defined earlier. Also depending on the size of the monitored CloudWatch custom metric 'Waiting for Publish', the Scaling Policy with Steps can add a difference number of instances to the group. The scaling policy sets the number of instances in group to 1 if there are between 1000 and 2000 items Waiting for Publish in the queue. It also sets the