我正在尝试根据动态条件加载数据。
string tempQry = string.Empty;
if (!string.IsNullOrEmpty(cusid) && !string.IsNullOrEmpty(mktid))
tempQry = "x=>x.MarketID==" + mktid + "&& x.MasterCustomerID==" + cusid;
if (string.IsNullOrEmpty(cusid))
tempQry = "x=>x.MarketID==" + mktid;
if (string.IsNullOrEmpty(mktid))
tempQry = "x=>x.MasterCustomerID==" + cusid;
_lstOptInInterest = new LinkedList<OptInInterestArea>(
(from a in _lstOptInInterest
join b in _marketoEntities.CustCommPreferences.Where(tempQry)
on new { CODE = a.Code, SUBCODE = a.SubCode } equals new { CODE = b.Option_Short_Name, SUBCODE = b.Option_Short_Subname }
into leftGroup
from b in leftGroup.DefaultIfEmpty()
select new OptInInterestArea()
{
Code = a.Code,
SubCode = a.SubCode,
SubCodeDescription = a.SubCodeDescription,
CodeDescription = a.CodeDescription,
PrevOptIn = b != null && b.OptedIn == true
}).ToList());
它给出编译错误Where(tempQry)
.
'System.Data.Entity.DbSet<Market.Data.CustCommPreference>' does not contain a definition for 'Where' and the best extension method overload 'System.Linq.Queryable.Where<TSource>(System.Linq.IQueryable<TSource>, System.Linq.Expressions.Expression<System.Func<TSource,bool>>)' has some invalid arguments
这要怎么处理呢?
Where
等待 lambda 形式而不是字符串形式的条件,因此您必须稍微重构一下代码(只是下面的一个想法):
IQueryable<CustCommPreference> query = _marketoEntities.CustCommPreferences.AsQueryable();
if (!string.IsNullOrEmpty(cusid))
query = query.Where(x => x.MasterCustomerID == cusid);
if (!string.IsNullOrEmpty(mktid))
query = query.Where(x => x.MarketID == mktid);
然后使用它:
...
join b in query
...
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