Question

I’m looking to implement a few nicer ways to use List in a couple of apps I’m working on. My current implementation looks like this.

MyPage.aspx.cs

protected void Page_Load(object sender, EventArgs e)
{
    BLL.PostCollection oPost = new BLL.PostCollection();
    oPost.OpenRecent();
    rptPosts.DataSource = oArt;
    rptPosts.DataBind();
}

BLL Class(s)

public class Post
{
    public int PostId { get; set; }
    public string PostTitle { get; set; }
    public string PostContent { get; set; }
    public string PostCreatedDate { get; set; }

    public void OpenRecentInitFromRow(DataRow row)
    {
        this.PostId = (int) row["id"];
        this.PostTitle = (string) row["title"];
        this.PostContent = (string) row["content"];
        this.PostCreatedDate = (DateTime) row["createddate"];
    }
}
public class PostCollection : List<Post>
{
    public void OpenRecent()
    {
        DataSet ds = DbProvider.Instance().Post_ListRecent();
        foreach (DataRow row in ds.Tables[0].Rows)
        {
            Post oPost = new Post();
            oPost.OpenRecentInitFromRow(row);
            Add(oPost);
        }
    }
}

Now while this is working all well and good, I’m just wondering if there is any way to improve it, and just make it cleaner that having to use the two different classes do to something I think can happen in just one class or using an interface.

Answer 1

For one thing, I wouldn’t derive from List<T> – you aren’t really specializing the behaviour.

I’d also suggest that you could make Post immutable (at least externally), and write a static method (or constructor) to create one based on a DataRow:

public static Post FromDataRow(DataRow row)

Likewise you can have a list method:

public static List<Post> RecentPosts()

which returns them. Admittedly that might be better as an instance method in some sort of DAL class, which will allow mocking etc. Alternatively, in Post:

public static List<Post> ListFromDataSet(DataSet ds)

Now, as for the use of List<T> itself – are you using .NET 3.5? If so, you could make this considerably neater using LINQ:

public static List<Post> ListFromDataSet(DataSet ds)
{
    return ds.Tables[0].AsEnumerable()
                       .Select(row => Post.FromDataRow(row))
                       .ToList();
}