/// <summary>
/// lambda表达式转换sql
/// 支持的方法:
/// Contains(支持List.Contains字段与字段Contains字符串),
/// StartsWith,EndsWith,=,!=,>,>=,小于,小于等于
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="select"></param>
/// <param name="query"></param>
/// <param name="orderByClauseList"></param>
/// <param name="pager"></param>
/// <param name="unSelect"></param>
/// <returns></returns>
private void FillFilter <T>(
Expression <Func <T, bool> > query = null,
Expression <Func <T, object> > select = null,
List <OrderByClause> orderByClauseList = null,
Pager pager = null,
Expression <Func <T, object> > unSelect = null) where T : class, new()
{
dtoDbMapping = DtoMappingHelper.GetDtoMapping <T>();
#region 处理查询条件
if (query != null)
{
Expression exp = query.Body as Expression;
HandleFilterExpression(exp);
}
#endregion
#region 处理排序
if (orderByClauseList != null && orderByClauseList.Count > 0)
{
for (int i = 0; i < orderByClauseList.Count; i++)
{
filter.AddOrderBy(orderByClauseList[i].FieldName, orderByClauseList[i].Order);
}
}
#endregion
#region 处理分页
if (pager != null)
{
filter.InitPage(pager.PageIndex, pager.PageSize);
}
#endregion
#region 处理查询属性
filter.Select = select;
filter.UnSelect = unSelect;
#endregion
}
/// <summary>
/// IL生成SetValueMethod内容
/// 独立出来为共用代码
/// </summary>
/// <typeparam name="T"></typeparam>
/// <param name="il"></param>
public static void ILGenerateSetValueMethodContent <T>(ILGenerator il)
{
LocalBuilder result = il.DeclareLocal(typeof(T));
il.Emit(OpCodes.Newobj, typeof(T).GetConstructor(Type.EmptyTypes));
il.Emit(OpCodes.Stloc, result);
//取出dr中所有的列名集合
il.DeclareLocal(typeof(DataColumnCollection));
il.Emit(OpCodes.Ldarg_0);
il.Emit(OpCodes.Callvirt, typeof(DataRow).GetMethod("get_Table"));
il.Emit(OpCodes.Callvirt, typeof(DataTable).GetMethod("get_Columns"));
il.Emit(OpCodes.Stloc_1); //var columns = dr.Table.Columns
List <PiMap> piMapList = DtoMappingHelper.GetPiMapList <T>();
foreach (PiMap piMap in piMapList)
{
if (piMap.IsIgnore || piMap.Pi.SetMethod == null)
{
continue;
}
//去掉关键词转义
string fieldName = piMap.FieldName.Replace("\"", "").Replace("'", "").Replace("[", "").Replace("]", "");
//加入判断条件 if (columns.Contains("Id") && !dataRow.IsNull("Id"))
var endIfLabel = il.DefineLabel();
il.Emit(OpCodes.Ldloc_1); //columns
il.Emit(OpCodes.Ldstr, fieldName); //Id
il.Emit(OpCodes.Callvirt, typeof(DataColumnCollection).GetMethod("Contains", new Type[] { typeof(string) }));
il.Emit(OpCodes.Brfalse, endIfLabel); //判断columns.Contains("Id")
il.Emit(OpCodes.Ldarg_0); //dr
il.Emit(OpCodes.Ldstr, fieldName); //Id
il.Emit(OpCodes.Callvirt, typeof(DataRow).GetMethod("IsNull", new Type[] { typeof(string) }));
il.Emit(OpCodes.Brtrue, endIfLabel); //判断dr.IsNull("Id")
//自DataReader中读取值 调用get_Item方法 dataRow["Id"]
il.Emit(OpCodes.Ldloc, result); //result
il.Emit(OpCodes.Ldarg_0); //dataRow
il.Emit(OpCodes.Ldstr, fieldName); //Id
il.Emit(OpCodes.Callvirt, typeof(DataRow).GetMethod("get_Item", new Type[] { typeof(string) }));
Type type = piMap.PropertyType; //拆箱
if (type.IsValueType)
{ //直接拆箱 可空类型,也可以直接拆箱
if (piMap.IsEnum)
{
if (type.GenericTypeArguments.Length > 0)
{ //如果为可空枚举类型,抛出异常
Type realType = type.GenericTypeArguments[0];
throw new Exception($"对象{typeof(T).Name}属性{piMap.Pi.Name}[{realType.Name}]转换异常.不支持可空枚举类型.");
}
}
il.Emit(OpCodes.Unbox_Any, type);
}
else
{ //引用类型
il.Emit(OpCodes.Castclass, type);
}
//给该属性设置对应值
il.Emit(OpCodes.Callvirt, piMap.Pi.GetSetMethod());
il.MarkLabel(endIfLabel);
}
/*给本地变量（result）返回值*/
il.Emit(OpCodes.Ldloc, result);
il.Emit(OpCodes.Ret);
}
