private void Clear()
{
SqlBuilder.Clear();
JoinRelations.Clear();
WhereClause.Clear();
Parameters.Clear();
OrderByFields.Clear();
GroupByFields.Clear();
SelectFields.Clear();
}
protected override Expression VisitMethodCall(MethodCallExpression methodExp)
{
if (methodExp.Method.Name == "OrderByDescending" || methodExp.Method.Name == "ThenByDescending")
{
OrderByFields.Clear();
OrderBy = "DESC";
Expression obj = this.Visit(((LambdaExpression)methodExp.Arguments[1]).Body);
OrderByFieldsStack.Insert(0, OrderByFields.ToString().TrimEnd(','));
OrderByFields.Clear();
if (methodExp.Arguments[0].NodeType == ExpressionType.Call)
{
this.Visit(methodExp.Arguments[0]);
}
return(methodExp);
}
else if (methodExp.Method.Name == "OrderBy" || methodExp.Method.Name == "ThenBy")
{
OrderByFields.Clear();
OrderBy = "ASC";
Expression obj = this.Visit(((LambdaExpression)methodExp.Arguments[1]).Body);
OrderByFieldsStack.Insert(0, OrderByFields.ToString().TrimEnd(','));
OrderByFields.Clear();
if (methodExp.Arguments[0].NodeType == ExpressionType.Call)
{
this.Visit(methodExp.Arguments[0]);
}
return(methodExp);
}
else
{
Expression obj = this.Visit(methodExp.Object);
object result = Expression.Lambda(methodExp).Compile().DynamicInvoke();
var r = Expression.Constant(result, methodExp.Method.ReturnType);
this.Visit(r);
return(r);
}
throw new NotSupportedException(string.Format("lambda表达式不支持使用此'{0}'方法", methodExp.Method.Name));
}