c# - LINQ group by property 作为参数

Question

我有一个要使用 LINQ 查询的对象列表。我希望能够按属性对它们进行分组。

var query = from item in expense
    orderby item.ExpenseTime descending
    group item by item.Location;

var query = from item in expense
    orderby item.ExpenseTime descending
    group item by item.ExpenseType;

var query = from item in expense
    orderby item.ExpenseTime descending
    group item by item.Person;

有没有办法将属性指定为方法的参数？

public static void GetExpensesBy(List<Expense> expense, Property myGroupingProperty)
{
    var query = from item in expense
                orderby item.ExpenseTime descending
                group item by item.myGroupingProperty;

    // ....
}

请注意，查询之后是通用的代码，不关心组。

Answer 1

如果你修改你的 GetExpenseBy 如下

public static void GetExpensesBy<TKey>(List<Expense> expense, 
                                       Func<Expense, TKey> myGroupingProperty)
{
    var query = (from item in expense
                 orderby item.ExpenseTime descending
                 select item).GroupBy(myGroupingProperty);
    // ....
}

然后你可以调用这个函数作为

GetExpensesBy(expense, item => item.Location);
GetExpensesBy(expense, item => item.Person);
GetExpensesBy(expense, item => item.ExpenseType);