我下面用linq去过滤数据报 转换格式错误

[c___s__d_n]

DataTable 数据如上图。。我下面用linq去过滤数据报 转换格式错误。。请教大家。。

 List<int> callTypes = new List<int> { 2, 3 };
            var  query = from data in ds.Tables[0].AsEnumerable()
                         where callTypes.Contains(data.Field<int>("CallType"))
                         group data by new { t1 = data.Field<int>("Ent_ID"), t2 = data.Field<string>("SDate") } into m
                         select new
                         {
                             
                             Ent_ID = m.Key.t1,
                             SDate = m.Key.t2,
                             CallAll = m.Select(x => x.Field<string>("CallCode")).Distinct().Count()
                         };
        foreach (var item in query)  //这里就报错了。。。
            {
                WriteSysLog(item.Ent_ID + "..." + item.SDate + "..." + item.CallAll);
            }

 var query_Trs_Suc = from data in ds.Tables[0].AsEnumerable()
                                let ToLen = data.Field<int>("TotalLen")
                                where data.Field<int>("CallType") == 2 && data.Field<string>("Called").Length > 5
                                && ToLen>0
                         group data by new { t1 = data.Field<int>("Ent_ID"), t2 = data.Field<string>("SDate") } into m
                         select new
                         {

                             Ent_ID = m.Key.t1,
                             SDate = m.Key.t2,
                             CallIn_TRS_Suc = m.Select(x => x.Field<string>("CallCode")).Distinct().Count()
                         };
            foreach (var item_trs_suc in query_Trs_Suc)
            {
                WriteSysLog(item_trs_suc.Ent_ID + "..." + item_trs_suc.SDate + "..." + item_trs_suc.CallIn_TRS_Suc);
            }

[Andy__Huang]

foreach (var item in query) 改为： foreach (var item in query.ToList())

[c___s__d_n]

引用 1 楼 hdhai9451 的回复:

foreach (var item in query) 改为： foreach (var item in query.ToList())

foreach (var item in query.ToList()) { WriteSysLog(item.Ent_ID + "..." + item.SDate + "..." + item.CallAll); } 改了，还是报一样错。。

[q107770540]

很明显，你的数据中 data.Field<int>("Ent_ID") 有NULL的情况

[q107770540]

var query = from data in ds.Tables[0].AsEnumerable() where callTypes.Contains(data.Field<int>("CallType")) group data by new { t1 = data.Field<int?>("Ent_ID"), t2 = data.Field<string>("SDate") } into m select new { Ent_ID = m.Key.t1.HasValue?m.Key.t1.Value:0, SDate = m.Key.t2, CallAll = m.Select(x => x.Field<string>("CallCode")).Distinct().Count() };

[c___s__d_n]

引用 4 楼 q107770540 的回复:

var query = from data in ds.Tables[0].AsEnumerable()
where callTypes.Contains(data.Field<int>("CallType"))
group data by new { t1 = data.Field<int?>("Ent_ID"), t2 = data.Field<string>("SDate") } into m
select new
{

Ent_ID = m.Key.t1.HasValue?m.Key.t1.Value:0,
SDate = m.Key.t2,
CallAll = m.Select(x => x.Field<string>("CallCode")).Distinct().Count()
};

试了下，还是报格式转换错误。。

我看出是因为 CallAll = m.Select(x => x.Field<string>("CallCode")).Distinct().Count()

报的错误

[q107770540]

仔细看我4楼的代码，我不止修改了一处： Ent_ID = m.Key.t1.HasValue?m.Key.t1.Value:0, 我觉得你的错误是在这里的tostring() WriteSysLog(item.Ent_ID.ToString() + "..." + item.SDate + "..." + item.CallAll.ToString());