如何使用匿名类型的动态OrderBy变量?

时间:2011-11-24 04:32:07

标签: c# linq dynamic .net-3.5

我在主页上有几个网站并加载文章。我可以在文章上设置排名,以不同的顺序显示它们,但文章的各个网站的排序可能不同。

我必须订购文章的代码为所有网站设置相同的订单:

    string officeLocation = "";
    // office location could be either World, Europe, Africa, America, Asia, Pacific

    var result = articles.Select(a => new
    {
        Title = a.Title,
        Url = a[SPBuiltInFieldId.FileRef],
        Byline = a[Constants.FieldNames.Byline],
        ArticleDate = a[Constants.FieldNames.ArticleStartDate],
        RankWorld = a[Constants.FieldNames.World],
        RankEurope = a[Constants.FieldNames.RankEurope],
        RankAfrica = a[Constants.FieldNames.RankAfrica],
        RankAmerica = a[Constants.FieldNames.RankAmerica],
        RankAsia = a[Constants.FieldNames.RankAsia],
        RankPacific = a[Constants.FieldNames.RankPacific],
    });

    rptArticles.DataSource = result.OrderBy(a => a.RankWorld);
    rptArticles.DataBind();

代码将所有排名设置为RankWorld(1-6)。

如果字符串officeLocation(传递给方法)是欧洲,那么我想按a.RankEurope排序,如果officeLocation是a.RankAsia的亚洲顺序,依此类推。< / p>

我怎样才能最好地实现这一目标(.NET 3.5)?

提前致谢。

1 个答案:

答案 0 :(得分:2)

假设您有一组固定的位置(按照定义,您必须拥有匿名类型),那么您可以使用一个开关:

string officeLocation = "";
// office location could be either World, Europe, Africa, America, Asia, Pacific

var result = articles.Select(a => new
{
    Title = a.Title,
    Url = a[SPBuiltInFieldId.FileRef],
    Byline = a[Constants.FieldNames.Byline],
    ArticleDate = a[Constants.FieldNames.ArticleStartDate],
    RankWorld = a[Constants.FieldNames.World],
    RankEurope = a[Constants.FieldNames.RankEurope],
    RankAfrica = a[Constants.FieldNames.RankAfrica],
    RankAmerica = a[Constants.FieldNames.RankAmerica],
    RankAsia = a[Constants.FieldNames.RankAsia],
    RankPacific = a[Constants.FieldNames.RankPacific],
});

switch (officeLocation)
{
    case "World": result = result.OrderBy(a => a.RankWorld); break;
    case "Europe": result = result.OrderBy(a => a.RankEurope); break;
    case "Africa": result = result.OrderBy(a => a.RankAfrica); break;
    case "America": result = result.OrderBy(a => a.RankAmerica); break;
    case "Asia": result = result.OrderBy(a => a.RankAsia); break;
    case "Pacific": result = result.OrderBy(a => a.RankPacific); break;
    default: throw new Exception("Unexpected location: " + officeLocation);
}

rptArticles.DataSource = result.OrderBy(a => a.RankWorld);
rptArticles.DataBind();

显然,您需要决定如何最好地处理意外的位置。

请注意,理想情况下,我刚刚将OrderBy功能分配给Func<T,R>,但只有一个OrderBy来电,但由于此处你不能这样做匿名类型。