/// <summary>
/// 通过Lambed Expression获取属性名称
/// </summary>
/// <param name="expr">查询表达式</param>
/// <returns></returns>
public static List <string> GetPiList <T>(Expression <Func <T, object> > expr)
{
List <string> result = new List <string>();
if (expr.Body is NewExpression)
{ // t=>new{t.Id,t.Name}
NewExpression nexp = expr.Body as NewExpression;
if (nexp.Members != null)
{
result = nexp.Members.Select(member => member.Name).ToList();
}
}
else if (expr.Body is NewObjectExpression)
{ // t=>new{t.Id,t.Name}
NewObjectExpression nexp = expr.Body as NewObjectExpression;
if (nexp.Members != null)
{
result = nexp.Members.Select(member => member.Name).ToList();
}
}
else if (expr.Body is UnaryExpression)
{ //t=>t.Id
UnaryExpression uexp = expr.Body as UnaryExpression;
MemberExpression mexp = uexp.Operand as MemberExpression;
result.Add(mexp.Member.Name);
}
else if (expr.Body is MemberExpression)
{ //t=>t.Id T为子类时
MemberExpression mexp = expr.Body as MemberExpression;
result.Add(mexp.Member.Name);
}
else
{
throw new System.Exception("不支持的Select lambda写法");
}
return(result);
}
/// <summary>
/// Expression And
/// NewExpression 合并
/// </summary>
/// <param name="expr"></param>
/// <returns></returns>
public static Expression <Func <T, object> > Add <T>(this Expression <Func <T, object> > expr, Expression <Func <T, object> > expandExpr)
{
Expression <Func <T, object> > result = null;
ParameterExpression parameter = Expression.Parameter(typeof(T), "p");
List <MemberInfo> memberInfoList = new List <MemberInfo>();
#region 处理原expr
if (expr.Body is NewExpression)
{ // t=>new{t.Id,t.Name}
NewExpression newExp = expr.Body as NewExpression;
if (newExp.Members != null)
{
memberInfoList = newExp.Members.ToList();
}
}
else if (expr.Body is NewObjectExpression)
{
NewObjectExpression newExp = expr.Body as NewObjectExpression;
if (newExp.Members != null)
{
memberInfoList = newExp.Members.ToList();
}
}
else if (expr.Body is UnaryExpression)
{ //t=>t.Id
UnaryExpression unaryExpression = expr.Body as UnaryExpression;
MemberExpression memberExp = unaryExpression.Operand as MemberExpression;
memberInfoList.Add(memberExp.Member);
}
else if (expr.Body is MemberExpression)
{ //t=>t.Id T为子类时
MemberExpression memberExp = expr.Body as MemberExpression;
memberInfoList.Add(memberExp.Member);
}
#endregion
#region 处理扩展expr
if (expandExpr.Body is NewExpression)
{ // t=>new{t.Id,t.Name}
NewExpression newExp = expandExpr.Body as NewExpression;
for (int i = 0; i < newExp.Members.Count; i++)
{
MemberExpression memberExp = Expression.Property(parameter, newExp.Members[i].Name);
if (!memberInfoList.Any(member => member.Name == newExp.Members[i].Name))
{
memberInfoList.Add(newExp.Members[i]);
}
}
}
else if (expr.Body is NewObjectExpression)
{
NewObjectExpression newExp = expr.Body as NewObjectExpression;
if (newExp.Members != null && newExp.Members.Count > 0)
{
for (int i = 0; i < newExp.Members.Count; i++)
{
MemberExpression memberExp = Expression.Property(parameter, newExp.Members[i].Name);
if (!memberInfoList.Any(member => member.Name == newExp.Members[i].Name))
{
memberInfoList.Add(newExp.Members[i]);
}
}
}
}
else if (expandExpr.Body is UnaryExpression)
{ //t=>t.Id
UnaryExpression unaryExpression = expandExpr.Body as UnaryExpression;
MemberExpression memberExp = unaryExpression.Operand as MemberExpression;
if (!memberInfoList.Any(exp => exp.Name == memberExp.Member.Name))
{
memberInfoList.Add(memberExp.Member);
}
}
#endregion
NewObjectExpression newObjExpression = new NewObjectExpression(typeof(object).GetConstructors()[0], null, memberInfoList);
result = Expression.Lambda <Func <T, object> >(newObjExpression, parameter);
return(result);
}
/// <summary>
/// Expression Remove
/// NewExpression 合并
/// </summary>
/// <param name="expr"></param>
/// <returns></returns>
public static Expression <Func <T, object> > Remove <T>(this Expression <Func <T, object> > expr, Expression <Func <T, object> > expandExpr)
{
Expression <Func <T, object> > result = null;
ParameterExpression parameter = Expression.Parameter(typeof(T), "p");
List <MemberInfo> memberInfoList = new List <MemberInfo>();
List <MemberInfo> removeMemberInfoList = new List <MemberInfo>();
#region 处理原expr
if (expr.Body is NewExpression)
{ // t=>new{t.Id,t.Name}
NewExpression newExp = expr.Body as NewExpression;
if (newExp.Members != null)
{
memberInfoList = newExp.Members.ToList();
}
}
else if (expr.Body is NewObjectExpression)
{
NewObjectExpression newExp = expr.Body as NewObjectExpression;
if (newExp.Members != null)
{
memberInfoList = newExp.Members.ToList();
}
}
else if (expr.Body is UnaryExpression)
{ //t=>t.Id
UnaryExpression unaryExpression = expr.Body as UnaryExpression;
MemberExpression memberExp = unaryExpression.Operand as MemberExpression;
memberInfoList.Add(memberExp.Member);
}
#endregion
#region 处理扩展expr
if (expandExpr.Body is NewExpression)
{ // t=>new{t.Id,t.Name}
NewExpression newExp = expandExpr.Body as NewExpression;
for (int i = 0; i < newExp.Members.Count; i++)
{
MemberExpression memberExp = Expression.Property(parameter, newExp.Members[i].Name);
if (!removeMemberInfoList.Any(member => member.Name == newExp.Members[i].Name))
{
removeMemberInfoList.Add(newExp.Members[i]);
}
}
}
else if (expr.Body is NewObjectExpression)
{
NewObjectExpression newExp = expr.Body as NewObjectExpression;
if (newExp.Members != null && newExp.Members.Count > 0)
{
for (int i = 0; i < newExp.Members.Count; i++)
{
MemberExpression memberExp = Expression.Property(parameter, newExp.Members[i].Name);
if (!removeMemberInfoList.Any(member => member.Name == newExp.Members[i].Name))
{
removeMemberInfoList.Add(newExp.Members[i]);
}
}
}
}
else if (expandExpr.Body is UnaryExpression)
{ //t=>t.Id
UnaryExpression unaryExpression = expandExpr.Body as UnaryExpression;
MemberExpression memberExp = unaryExpression.Operand as MemberExpression;
if (!memberInfoList.Any(exp => exp.Name == memberExp.Member.Name))
{
removeMemberInfoList.Add(memberExp.Member);
}
}
#endregion
for (int i = memberInfoList.Count - 1; i >= 0; i--)
{
if (removeMemberInfoList.Any(member => member.Name == memberInfoList[i].Name))
{
memberInfoList.Remove(memberInfoList[i]);
}
}
if (memberInfoList.Count <= 0)
{
throw new System.Exception("Expression Remove Error.All Properties are removed.");
}
NewObjectExpression newObjExpression = new NewObjectExpression(typeof(object).GetConstructors()[0], null, memberInfoList);
result = Expression.Lambda <Func <T, object> >(newObjExpression, parameter);
return(result);
}
