c#中利用委托反射將DataTable轉換為實體集的代碼

2020-01-24 03:41:05

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類泛型的約束：

復制代碼代碼如下:

public static class ToModel<T> where T : class, new()

定義委托：

復制代碼代碼如下:

public delegate void SetString(string value);

創建委托方法：

復制代碼代碼如下:

 
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：

復制代碼代碼如下:

 
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：

復制代碼代碼如下:

public delegate void SetString<PT>(PT value)

創建委托方法（這里有問題，不知如何處理）：

復制代碼代碼如下:

 
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：

復制代碼代碼如下:

 
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：

復制代碼代碼如下:

 
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; 
} 
} 
} 