如何按属性名筛选类列表？

Question

我想通过作为字符串的属性名筛选类的集合。假设我有一个名为Person的类，我有它的一个集合，或者是IEnumerable或者是List，我想过滤这个集合，但是我不知道确切的过滤器，我的意思是我不能使用：

person.Where(x => x.Id == 1);

让我举一个例子。

public class Person
{
    public int Id { get; set; }
    public string Name { get; set; }
    public int YearOfBorn {get; set;}    
}

List<Person> p = new List<Person>();

public List<Person> Filter(string propertyName, string filterValue, List<Person> persons)

Answer 1

从技术上讲，您可以尝试使用反射：

using System.Reflection;

... 

// T, IEnumerable<T> - let's generalize it a bit
public List<T> Filter<T>(string propertyName, string filterValue, IEnumerable<T> persons) {
  if (null == persons)
    throw new ArgumentNullException("persons");
  else if (null == propertyName)
    throw new ArgumentNullException("propertyName");

  PropertyInfo info = typeof(T).GetProperty(propertyName);

  if (null == info)
    throw new ArgumentException($"Property {propertyName} hasn't been found.", 
                                 "propertyName");

  // A bit complex, but in general case we have to think of
  //   1. GetValue can be expensive, that's why we ensure it calls just once
  //   2. GetValue as well as filterValue can be null
  return persons
    .Select(item => new {
      value = item,
      prop = info.GetValue(item),
    })
    .Where(item => null == filterValue
       ? item.prop == null
       : item.prop != null && string.Equals(filterValue, item.prop.ToString()))
    .Select(item => item.value)
    .ToList();
}