where子句

Question

我试图创建一个LINQ查询where子句是根据用户的选择构造的可变

if (!string.IsNullOrEmpty(txbbox.Text)) 
{ 

    query = "s.date== DateTime.Parse(txbbox.Text)"; 
} 

if (!string.IsNullOrEmpty(txbbox.Text)) 
{ 
    query = query + " & (s.type.Contains(txbbox.Text))"; 
} 

有一种方法通过内置在where子句中的变量在LINQ查询C＃的LINQ ？

Stemp = (from s in SList 
       where ***query*** 
       orderby s.DataScadenza 
       select s).ToList(); 

Answer 1

是;在这种情况下很简单，实际上是：

IEnumerable<Whatever> query = SList; // avoid var here, as will impact later assignment 
    if (!string.IsNullOrEmpty(txbbox.Text)) 
    { 
     var when = DateTime.Parse(txbbox.Text); // to avoid parsing per item 
     query = query.Where(s => s.date == when); 
    } 
    if (!string.IsNullOrEmpty(txbbox.Text)) 
    { 
     query = query.Where(s => s.type.Contains(txbbox.Text)); 
    } 
    Stemp = query.OrderBy(s => s.DateScadenze).ToList();