DataTable转List<Model>通用类【实体转换辅助类】

/// <summary>

/// DataTable转List<Model>通用类【实体转换辅助类】

/// </summary>

public class ModelConvertHelper<T> where T : new()

{

public static IList<T> ConvertToModel(DataTable dt)

{

// 定义集合

IList<T> ts = new List<T>();

// 获得此模型的类型

Type type = typeof(T);

string tempName = "";

foreach (DataRow dr in dt.Rows)

{

T t = new T();

// 获得此模型的公共属性

PropertyInfo[] propertys = t.GetType().GetProperties();

foreach (PropertyInfo pi in propertys)

{

tempName = pi.Name; // 检查DataTable是否包含此列

if (dt.Columns.Contains(tempName))

{

// 判断此属性是否有Set

if (!pi.CanWrite) continue;

object value = dr[tempName];

if (value != DBNull.Value)

pi.SetValue(t, value, null);

}

}

ts.Add(t);

}

return ts;

}

}

//方法二：使用emit实现
public static List<TResult> ToList<TResult>(this DataTable dt) where TResult : class, new()

{

List<TResult> list = new List<TResult>();

if (dt == null) return list;

DataTableEntityBuilder<TResult> eblist = DataTableEntityBuilder<TResult>.CreateBuilder(dt.Rows[0]);

foreach(DataRow info in dt.Rows) list.Add(eblist.Build(info));

dt.Dispose(); dt = null;

return list;

}

public class DataTableEntityBuilder<Entity>

{

private static readonly MethodInfo getValueMethod = typeof(DataRow).GetMethod("get_Item", new Type[] { typeof(int) });

private static readonly MethodInfo isDBNullMethod = typeof(DataRow).GetMethod("IsNull", new Type[] { typeof(int) });

private delegate Entity Load(DataRow dataRecord);

private Load handler;

private DataTableEntityBuilder() { }

public Entity Build(DataRow dataRecord) {

return handler(dataRecord);

}

public static DataTableEntityBuilder<Entity> CreateBuilder(DataRow dataRecord) {

DataTableEntityBuilder<Entity> dynamicBuilder = new DataTableEntityBuilder<Entity>();

DynamicMethod method = new DynamicMethod("DynamicCreateEntity", typeof(Entity), new Type[] { typeof(DataRow) }, typeof(Entity), true);

ILGenerator generator = method.GetILGenerator();

LocalBuilder result = generator.DeclareLocal(typeof(Entity));

generator.Emit(OpCodes.Newobj, typeof(Entity).GetConstructor(Type.EmptyTypes));

generator.Emit(OpCodes.Stloc, result);

for (int i = 0; i < dataRecord.ItemArray.Length; i++) {

PropertyInfo propertyInfo = typeof(Entity).GetProperty(dataRecord.Table.Columns[i].ColumnName);

Label endIfLabel = generator.DefineLabel();

if (propertyInfo != null && propertyInfo.GetSetMethod() != null) {

generator.Emit(OpCodes.Ldarg_0);

generator.Emit(OpCodes.Ldc_I4, i);

generator.Emit(OpCodes.Callvirt, isDBNullMethod);

generator.Emit(OpCodes.Brtrue, endIfLabel);

generator.Emit(OpCodes.Ldloc, result);

generator.Emit(OpCodes.Ldarg_0);

generator.Emit(OpCodes.Ldc_I4, i);

generator.Emit(OpCodes.Callvirt, getValueMethod);

generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);

generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod());

generator.MarkLabel(endIfLabel);

}

}

generator.Emit(OpCodes.Ldloc, result);

generator.Emit(OpCodes.Ret);

dynamicBuilder.handler = (Load)method.CreateDelegate(typeof(Load));

return dynamicBuilder;

}

}