看下面的代码我想用参数字段中接收的字段名替换USERNAME.这种方法必须能够对几个字段进行一些搜索.
谢谢,
public void Searching(string field,string stringToSearch)
{
var res =
from user in _dataContext.USERs where
user.USERNAME.Contains(stringToSearch)
select new
{
Id = user.ID,Username = user.USERNAME
};
}
解决方法
你需要忘记匿名类型,也许使用Tuple< int,string>代替;但是：怎么样：
IQueryable<Foo> source = // YOUR SOURCE HERE
// in-memory dummy example:
// source = new[] {
// new Foo {Id = 1,Bar = "abc"},// new Foo {Id = 2,Bar = "def"}
// }.AsQueryable();
string field = "Bar";
string stringToSearch = "d";
var param = Expression.Parameter(typeof (Foo),"x");
var predicate = Expression.Lambda<Func<Foo,bool>>(
Expression.Call(
Expression.PropertyOrField(param,field),"Contains",null,Expression.Constant(stringToSearch)
),param);
var projection = Expression.Lambda<Func<Foo,Tuple<int,string>>>(
Expression.Call(typeof(Tuple),"Create",new[] {typeof(int),typeof(string)},Expression.PropertyOrField(param,"Id"),field)),param);
Tuple<int,string>[] data = source.Where(predicate).Select(projection).ToArray();
