【转】C# 遍历类的属性并取出值

遍历一个实体，得到实体的名称和类型：

namespace WeiXinApi.CommonCS
{
    public class ForeachClass
    {
        /// <summary>
        /// C#反射遍历对象属性
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="model">对象</param>
        public static void ForeachClassProperties<T>(T model)
        {
            Type t = model.GetType();
            PropertyInfo[] PropertyList = t.GetProperties();
            foreach (PropertyInfo item in PropertyList)
            {
                string name = item.Name;
                object value = item.GetValue(model, null);
            }
        }
    }
}

改：

/// <summary>
        /// C#反射遍历对象属性
        /// </summary>
        /// <typeparam name="T">对象类型</typeparam>
        /// <param name="model">对象</param>
        public static void ForeachClassProperties<T>(T model)
        {
            Type t = model.GetType();
            PropertyInfo[] PropertyList = t.GetProperties();
            foreach (PropertyInfo item in PropertyList)
            {
                string name = item.Name;
                object value = item.GetValue(model, null);
                
                Console.WriteLine(name);

                if (item.PropertyType.IsGenericType && item.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
                {
                    // If it is NULLABLE, then get the underlying type. eg if "Nullable<int>" then this will return just "int"
                    var columnType = item.PropertyType.GetGenericArguments()[0];
                    Console.WriteLine(columnType);
                }
                else
                {
                    Console.WriteLine(item.PropertyType.Name);
                }
                Console.WriteLine();
            }
        }

在我们的应用程序中我们使用类描述我们的业务对象，为我们产生一些报表之类的，那就依赖大量不同的对象，我们创建一个帮助方法来转换我们的业务对象，或是一个List的业务对象到DataTables.

由于数据库表中字段可为null,对应.net 2.0以后我们可用Nullable类型来实现，那当我们业务对象类中字段有null时，并需要转换为DataTable时，这个场景产生，你可能用到以下方法：

/// <summary>
 /// Converts a Generic List into a DataTable
 /// </summary>
 /// <param name="list"></param>
 /// <param name="typ"></param>
 /// <returns></returns>
 private DataTable GetDataTable(IList list, Type typ)
 {
     DataTable dt = new DataTable();

     // Get a list of all the properties on the object
     PropertyInfo[] pi = typ.GetProperties();

     // Loop through each property, and add it as a column to the datatable
     foreach (PropertyInfo p in pi)
     {
         // The the type of the property
         Type columnType = p.PropertyType;

         // We need to check whether the property is NULLABLE
         if (p.PropertyType.IsGenericType && p.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
         {
             // If it is NULLABLE, then get the underlying type. eg if "Nullable<int>" then this will return just "int"
             columnType = p.PropertyType.GetGenericArguments()[0];
         }

         // Add the column definition to the datatable.
         dt.Columns.Add(new DataColumn(p.Name, columnType));
     }

     // For each object in the list, loop through and add the data to the datatable.
     foreach (object obj in list)
     {
         object[] row = new object[pi.Length];
         int i = 0;

         foreach (PropertyInfo p in pi)
         {
             row[i++] = p.GetValue(obj, null);
         }

         dt.Rows.Add(row);
     }

     return dt;
 }

上面的代码的关键点：

• 用 PropertyType.IsGenericType 决定property是否是generic类型
• 用 ProprtyType.GetGenericTypeDefinition() == typeof(Nullable<>) 检测它是否是一个nullable类型
• 用 PropertyType.GetGenericArguments() 获取基类型。

下面让我们来应用一下：

public class Person
{
    public string Name { get; set; }
    public DateTime DateOfBirth { get; set; }
    public DateTime? DateOfDeath { get; set; }
}

public class Example
{
    public static DataTable RunExample()
    {
        Person edward = new Person() { Name = "Edward", DateOfBirth = new DateTime(1900, 1, 1), DateOfDeath = new DateTime(1990, 10, 15) };
        Person margaret = new Person() { Name = "Margaret", DateOfBirth = new DateTime(1950, 2, 9), DateOfDeath = null };
        Person grant = new Person() { Name = "Grant", DateOfBirth = new DateTime(1975, 6, 13), DateOfDeath = null };

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

        people.Add(edward);
        people.Add(margaret);
        people.Add(grant);

        DataTable dt = GetDataTable(people, typeof(Person));

        return dt;
    }
}

将返回的DataTable像下面的内容: