Question

我正在尝试通过if语句调整我的查询，如下所示：

        IQueryable articles = null;

        if (User.IsInRole("Admin"))
        {
            articles = from s in db.Articles
                       select s;
        }
        if (User.IsInRole("Educator"))
        {
            articles = from s in db.Articles
                       where s.createdBy == WebSecurity.CurrentUserName
                       select s;

        }

这似乎没有给我任何错误。但是，当我尝试使用where子句进行更多过滤时，它无法识别该术语。我理解IQuerable不支持它，但有没有办法将“articles”设置为null，然后用if语句设置它？

if (!String.IsNullOrEmpty(searchString))
        {
            articles = articles.Where(s => s.title.ToUpper().Contains(searchString.ToUpper())
                                   || s.content.ToUpper().Contains(searchString.ToUpper()));
        }
        switch (sortOrder)
        {
            case "name_desc":
                articles = articles.OrderByDescending(s => s.title);
                break;
            case "Date":
                articles = articles.OrderBy(s => s.dateCreated);
                break;
            case "date_desc":
                articles = articles.OrderByDescending(s => s.dateCreated);
                break;
            case "rating_desc":
                articles = articles.OrderByDescending(s => s.finalReview);
                break;
            case "Rating":
                articles = articles.OrderBy(s => s.finalReview);
                break;
            case "Views":
                articles = articles.OrderBy(s=>s.numViews);
                break;
            case "views_desc":
                articles = articles.OrderByDescending(s => s.numViews);
                break;
            case "Educators":
                articles = articles.OrderBy(s => s.educatorCRUD);
                break;
            case "educators_desc":
                articles = articles.OrderByDescending(s => s.educatorCRUD);
                break;
            default:
                articles = articles.OrderBy(s => s.title);
                break;
        }

我知道我可以在一个大的if语句中执行此操作if（User.IsInRole（“Admin”））然后执行所有代码然后将相同的代码复制并粘贴到不同的if语句中（if（user.IsInRole（“Educator”））），但我认为这是多余且非常糟糕的编码实践。

干杯。

Answer 1

您的articles变量使用的是非泛型类型IQueryable，它实际上支持的很少。

您希望IQueryable<T>获得合适的<T>。例如：

IQueryable<Article> articles;
// Initialize as before

我个人会改变你的初始化方式：

IQueryable<Article> articles = db.Articles;
if (User.IsInRole("Admin"))
{
    // No change...
}
else if (User.IsInRole("Educator"))
{
    articles = articles.Where(s => s.createdBy == WebSecurity.CurrentUserName);
}
else
{
    // Throw an exception? What do you want to happen if they're neither an
    // educator nor an administrator?
}

Linq不包含＆＃39; Where＆＃39;的定义。

1 个答案: