類泛型的約束：
public static class ToModel<T> where T : class, new()
定義委托：
public delegate void SetString(string value);
創建委托方法：
private static SetString CreateStringDelegate(T model, string propertyName)
{
MethodInfo mi = model.GetType().GetProperty(propertyName).GetSetMethod();
Type type = typeof(SetString);
return Delegate.CreateDelegate(type, model, mi) as SetString;
}
利用反射和委托將DataTable轉換為實體集：
public static IList<T> GetDelegate_ToModelList(DataTable dt)
{
IList<T> list = new List<T>();
if (dt == null || dt.Rows.Count < 1) return list;
SetString setDelegateString;
foreach (DataRow dr in dt.Rows)
{
T model = new T();
foreach (DataColumn dc in dt.Columns)
{
setDelegateString = CreateStringDelegate(model, dc.ColumnName);
setDelegateString(dr[dc.ColumnName].ToString());
}
list.Add(model);
}
return list;
}
這樣寫問題就來了，因為委托定義的參數時string類型的，因為我們實體中可能有int或者DateTime類型的，這時就需要用上泛型委托了
如果這樣定義委托：
public delegate void SetString<PT>(PT value)
創建委托方法（這里有問題，不知如何處理）：
private static SetString CreateStringDelegate(T model, string propertyName)
{
MethodInfo mi = model.GetType().GetProperty(propertyName).GetSetMethod();
Type type = typeof(model).GetProperty(propertyName).PropertyType;
return Delegate.CreateDelegate(type, model, mi) as SetString<type>;
}
利用反射和委托將DataTable轉換為實體集：
public static IList<T> GetDelegate_ToModelList(DataTable dt)
{
IList<T> list = new List<T>();
if (dt == null || dt.Rows.Count < 1) return list;
foreach (DataRow dr in dt.Rows)
{
T model = new T();
foreach (DataColumn dc in dt.Columns)
{
SetString<typeof(T).GetProperty(dc.ColumnName).PropertyType> setDelegateString = CreateStringDelegate(model, dc.ColumnName);
setDelegateString(dr[dc.ColumnName].ToString());
}
list.Add(model);
}
return list;
}
一直疑惑著，希望有人幫我解決疑惑，直接反射的方法我也有，但是這個問題不解決，心里一直有疙瘩，希望有人幫幫忙，謝謝
泛型可以動態構建的，你了解了這個，就能解決了，附上我的簡略代碼：
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Data;
using System.Reflection;
namespace RftToModel {
class Program {
static void Main(string[] args) {
var result = ToModel<TestModel>.GetDelegate_ToModelList(BuildSampleTable());
foreach (var item in result) {
Console.WriteLine(item);
}
Console.Read();
}
static DataTable BuildSampleTable() {
DataTable result = new DataTable();
result.Columns.Add("ID", typeof(int));
result.Columns.Add("Name", typeof(string));
result.Columns.Add("IsDeleted", typeof(bool));
result.Rows.Add(new object[] { 1, "M.K", false });
result.Rows.Add(new object[] { 2, "B.G", true });
return result;
}
}
public class TestModel {
public int ID { get; set; }
public string Name { get; set; }
public bool IsDeleted { get; set; }
public override string ToString() {
return string.Format("ID:{0} Name:{1} IsDeleted:{2}", ID, Name, IsDeleted);
}
}
public delegate void SetValue<T>(T value);
public static class ToModel<T> where T : class, new() {
private static Delegate CreateSetDelegate(T model, string propertyName) {
MethodInfo mi = model.GetType().GetProperty(propertyName).GetSetMethod();
//這里構造泛型委托類型
Type delType = typeof(SetValue<>).MakeGenericType(GetPropertyType(propertyName));
return Delegate.CreateDelegate(delType, model, mi);
}
private static Type GetPropertyType(string propertyName) {
return typeof(T).GetProperty(propertyName).PropertyType;
}
public static IList<T> GetDelegate_ToModelList(DataTable dt) {
IList<T> list = new List<T>();
if (dt == null || dt.Rows.Count < 1) return list;
Delegate setDelegate;
foreach (DataRow dr in dt.Rows) {
T model = new T();
foreach (DataColumn dc in dt.Columns) {
setDelegate = CreateSetDelegate(model, dc.ColumnName);
//這里改變類型
setDelegate.DynamicInvoke(Convert.ChangeType(dr[dc.ColumnName], GetPropertyType(dc.ColumnName)));
}
list.Add(model);
}
return list;
}
}
}
謝謝，我剛修改了，我傳進去SqlDataReader和DataTable都可以轉換了，當時只想著每次返回一個特定類型等委托都不知道如何下手，看著你的方法解決了
沒想到DynamicInvoke這個方法，算是學習了，你的代碼寫著層次好清晰，看了是一種享受，向你學習?。?
