list.orderby 动态指定排序列与类型
public List<Abc> Get(string Order,string Sort)
{
//如果这样写,就默认是按ModuleTypeId进行ASC排序
List<Abc> listAbc = Abc.GetAll().OrderBy(k => k.AbcId).ToList();
return listAbc;
//用什么办法可以根据传进来的Order参数确定排序的列,根据Sort确定排序类型?
}
public List<Abc> Get(string Order, string Sort)
{
//如果这样写,就默认是按ModuleTypeId进行ASC排序
List<Abc> listAbc = Abc.GetAll().OrderBy(k => string.Compare(Sort, "xxxxx") == 0 ? k.AbcId : k.ModuleTypeId).ToList();
return listAbc;
}
var param = Expression.Parameter(typeof(ABC), "k");
var body = Expression.MakeMemberAccess(param, typeof(ABC).GetProperty(Sort));
var lambdaexpr = Expression.Lambda(param, body);
return List<Abc> listAbc = Abc.GetAll().OrderBy(lambdaexpr.Compile() as Func<Abc, ICompareable>).ToList();
class Pet
{
public string Name{get;set;}
public int Age{get;set;}
}
void Main()
{
Pet[] pets = { new Pet { Name="Tim", Age=18 },
new Pet { Name="Allen", Age=22 },
new Pet { Name="Bill", Age=20 } };
//如果我们想根据Age进行排序 很容易想到这样来写:
var query= from p in pets
orderby p.Age
select p;
query.ToList().ForEach(q=>Console.WriteLine(q.Name +" "+q.Age));
/* 得到结果:
Tim 18
Bill 20
Allen 22
*/
}
//但是有时项目内有多个排序条件 如有时要根据Name排序 有时要根据Age排序
//这时我们就要用到动态排序:
void Main()
{
Pet[] pets = { new Pet { Name="Tim", Age=18 },
new Pet { Name="Allen", Age=22 },
new Pet { Name="Bill", Age=20 } };
Console.WriteLine("Before Orderby:/r/n");
pets.ToList().ForEach(p=>Console.WriteLine(p.Name +" "+p.Age));
var query= from p in pets
orderby GetPropertyValue(p,"Age")
select p;
Console.WriteLine("/r/nAfter Orderby:/r/n");
query.ToList().ForEach(q=>Console.WriteLine(q.Name +" "+q.Age));
/*
Before Orderby:
Tim 18
Allen 22
Bill 20
After Orderby:
Tim 18
Bill 20
Allen 22
*/
}
private static object GetPropertyValue(object obj, string property)
{
System.Reflection.PropertyInfo propertyInfo=obj.GetType().GetProperty(property);
return propertyInfo.GetValue(obj, null);
}