/// <summary>
/// 分页查询，基础方法，参数：页面大小，页码，主键，查询字段，表达式，排序，数据总条数
/// </summary>
/// <param name="pageSize">页面大小</param>
/// <param name="pageIndex">页码</param>
/// <param name="primaryKey">主键</param>
/// <param name="selectFields">查询字段</param>
/// <param name="express">表达式</param>
/// <param name="orderBy">排序</param>
/// <param name="recordCount">数据总条数</param>
/// <returns></returns>
private List <TEntity> Search(int pageSize, int pageIndex, string primaryKey, string selectFields, List <Expression> express, string orderBy, ref int recordCount)
{
//获取参数和条件
CoreFrameworkEntity CoreFrameworkEntity = GetParaListAndWhere(express);
//条件
string where = CoreFrameworkEntity.where;
//参数列表
List <SqlParameter> listPara = CoreFrameworkEntity.paraList;
selectFields = selectFields == "" ? "*" : selectFields;//查询字段
Pager page = new Pager();
IDataReader sdr = page.GetPagerInfo(tableName, primaryKey, selectFields, pageSize, pageIndex, where, orderBy, ref recordCount, listPara);
return(DynamicBuilder <TEntity> .GetList(sdr, columnAttrList));
}
/// <summary>
/// 不分页查询,基础方法
/// </summary>
/// <param name="count">显示总数，空则全部显示</param>
/// <param name="selectFields">查询字段</param>
/// <param name="express">表达式</param>
/// <param name="orderBy">排序,为空则不排序</param>
/// <returns></returns>
private List <TEntity> Search(int?count, string selectFields, List <Expression> express, string orderBy)
{
//获取参数和条件
CoreFrameworkEntity CoreFrameworkEntity = GetParaListAndWhere(express);
//条件
string where = CoreFrameworkEntity.where;
//参数列表
List <SqlParameter> listPara = CoreFrameworkEntity.paraList;
selectFields = selectFields == "" ? "*" : selectFields; //查询字段
orderBy = orderBy == "" ? "" : "order by " + orderBy; //排序
string topStr = count.HasValue == false ? "" : " top " + count + " ";
string cmdText = "select " + topStr + selectFields + " from " + tableName + " where " + where + " " + orderBy;
IDataReader sdr = new SqlConvertHelper().ExecuteReader(cmdText, listPara);
return(DynamicBuilder <TEntity> .GetList(sdr, columnAttrList));
}
public static DynamicBuilder <T> CreateBuilder(IDataRecord dataRecord, List <EntityPropColumnAttributes> attributeList)
{
DynamicBuilder <T> dynamicBuilder = new DynamicBuilder <T>();
//定义一个名为DynamicCreate的动态方法，返回值typof(T)，参数typeof(IDataRecord)
DynamicMethod method = new DynamicMethod("DynamicCreate", typeof(T), new Type[] { typeof(IDataRecord) }, typeof(T), true);
ILGenerator generator = method.GetILGenerator(); //创建一个MSIL生成器，为动态方法生成代码
LocalBuilder result = generator.DeclareLocal(typeof(T)); //声明指定类型的局部变量 可以T t;这么理解
//The next piece of code instantiates the requested type of object and stores it in the local variable. 可以t=new T();这么理解
generator.Emit(OpCodes.Newobj, typeof(T).GetConstructor(Type.EmptyTypes));
generator.Emit(OpCodes.Stloc, result);
for (int i = 0; i < dataRecord.FieldCount; i++)//数据集合，熟悉的for循环 要干什么你懂的
{
var list = attributeList.Where(w => w.fieldName.ToLower() == dataRecord.GetName(i).ToLower());
if (list.Count() > 0)
{
T t = System.Activator.CreateInstance <T>(); //typeof(T)
PropertyInfo propertyInfo = t.GetType().GetProperty(list.First().propName); //根据列名取属性 原则上属性和列是一一对应的关系
Label endIfLabel = generator.DefineLabel();
if (propertyInfo != null && propertyInfo.GetSetMethod() != null)//实体存在该属性 且该属性有SetMethod方法
{
/*The code then loops through the fields in the data reader, finding matching properties on the type passed in.
* When a match is found, the code checks to see if the value from the data reader is null.
*/
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, isDBNullMethod);//就知道这里要调用IsDBNull方法 如果IsDBNull==true contine
generator.Emit(OpCodes.Brtrue, endIfLabel);
/*If the value in the data reader is not null, the code sets the value on the object.*/
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ldarg_0);
generator.Emit(OpCodes.Ldc_I4, i);
generator.Emit(OpCodes.Callvirt, getValueMethod); //调用get_Item方法
generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod()); //给该属性设置对应值
generator.MarkLabel(endIfLabel);
//if (propertyInfo.PropertyType.FullName != "System.Guid")
//{
//}
//else
//{
// generator.Emit(OpCodes.Ldloc, result);
// generator.Emit(OpCodes.Ldarg_0);
// generator.Emit(OpCodes.Ldc_I4, i);
// generator.Emit(OpCodes.Callvirt, getGuidValueMethod);//调用get_Item方法
// generator.Emit(OpCodes.Unbox_Any, propertyInfo.PropertyType);
// generator.Emit(OpCodes.Callvirt, propertyInfo.GetSetMethod());//给该属性设置对应值
// generator.MarkLabel(endIfLabel);
// //propertyInfo.SetValue(t, Convert.ChangeType(propertyInfo.GetSetMethod(),propertyInfo.PropertyType),null);
//}
}
}
}
/*The last part of the code returns the value of the local variable*/
generator.Emit(OpCodes.Ldloc, result);
generator.Emit(OpCodes.Ret);//方法结束，返回
//完成动态方法的创建，并且创建执行该动态方法的委托，赋值到全局变量handler,handler在Build方法里Invoke
dynamicBuilder.handler = (Load)method.CreateDelegate(typeof(Load));
return(dynamicBuilder);
}