Question

public IEnumerable<User> GetUsers(string location, string role, bool excludeHeadOffice )
{
    var users = from u in DataContext.Users
        where
            (u.location == location || location == null) &&
            (u.role == role || role == null)

    return users;           
}

我想要做的是，还有一个像这样的额外过滤器：

(excludeHeadOffice && u.location != "ho")

如何将此表达式添加到现有的where子句？

更新的如果excludeHeadOffice为true，则应使用过滤器

(excludeHeadOffice && u.location != "ho")

否则它应该像以前一样使用：

 (u.location == location || location == null)

Answer 1

你只需要仔细思考并提出必要的布尔逻辑：

df = read.table(text = "shop_id,item_id,time,value
150,1,2015-07-10,3
150,1,2015-07-11,5
150,1,2015-07-13,2
150,2,2015-07-10,15
150,2,2015-07-12,12", header = TRUE, sep = ",")

Answer 2

这是你在找什么？

public IEnumerable<User> GetUsers(string location, string role, bool excludeHeadOffice = false)
{
    var users = from u in DataContext.Users
    where
        (u.location == location || location == null) &&
        (u.role == role || role == null)

    if(excludeHeadOffice)
    {
      return users.Where(u => u.location != "headOfficeLocation" && u.location !="ho");
    }
    return users;           
 }

Answer 3

在多个语句中构建您的查询。

使用扩展方法可以（可以说）更容易构建它：

var query = DataContext.Users.AsQueryable();

if (excludeHeadOffice)
    query = query.Where(x => x.location != "ho");
else if (location != null)
    query = query.Where(x => x.location == location);

if (role != null)
    query = query.Where(x => x.role == role);

return query;

这里的想法是你从一个基地开始＆＃34;让我得到一切＆＃34;查询，并继续添加if语句。

如何根据参数添加布尔过滤器

3 个答案: