Question

linq如何实现动态多条件查询

例如可以按照一个条件查询 也可以2个条件 或者3个 4个, 是不固定的,表示层调数据访问层的方法 求解!

Answer 1

我的做法是判断，然后筛选条件

public MyInfoResult GetInfoes(int intPage, int intPageSize, int intFictionID, int intPID, string strKeyword, int intState,
DateTime? dateStart, DateTime? dateEnd, string strOrderby)
{
myInfoResult = new MyInfoResult();
try
{
Fiction myDal = new Fiction(_ConnectionString);
IQueryable<TblSectionInfo> query = myDal.TblSectionInfo;

List<int> infotreeids = new List<int>();

if (intFictionID != -1)
{
query = query.Where(i => i.FkFictionID == intFictionID);
}
if (intPID != -1)
{
query = query.Where(i => i.ParentID == intPID);
}
if (!string.IsNullOrEmpty(strKeyword))
{
query = query.Where(i => i.SectionName.Contains(strKeyword));
}
if (intState != -1)
{
query = query.Where(i => i.State == intState);
}
if (dateStart != null)
{
query = query.Where(i => i.AddDate >= dateStart);
}
if (dateEnd != null)
{
query = query.Where(i => i.AddDate <= dateEnd);
}

query = IQueryable.MyOrderBy(query, strOrderby);

myInfoResult.IsSuc = true;
myInfoResult.Message = query.AsEnumerable().Skip(intPage * intPageSize).Take(intPageSize).ToList();
myInfoResult.MsgCount = query.Count();
}
catch (Exception error)
{
myInfoResult.IsSuc = false;
myInfoResult.Message = error.Message;
}
return myInfoResult;
}

Answer 2

使用表达式树吧