从列表中查找丢失的ID <int> 在数据表中

Question

I have a List and a DataTable which contains a column to match the IDs in the list. I need to identify all IDs in my list that are not in the DataTable. I tried getting an IEnumberable DataRow and joining that to the list but I'm not able to identify the missing ones.

Here is my code and what I've tried...

List<int> JobIdList = (from i in EntryItems select i.JobID.Value).ToList<int>();
IEnumerable<DataRow> rowInfo = JobBLL.JobsExist(JobIdList).AsEnumerable();

var MissingList = (from rec in rowInfo
                    join id in JobIdList
                    on rec.Field<int>("JobID") equals id
                    into grouping
                    from id in grouping.DefaultIfEmpty()
                    select new { id }).ToList();

if (MissingList.Count > 0) { // Show message and exit }

The problem is that this returns the items in the data table that ARE found. Let's say I have 1, 2, and 3 in my list but my data table only has 1 and 3. I want to have 2 in MissingList.

Any thoughts?

Answer 1

var jobIdList = new HashSet<int>(from i in EntryItems select i.JobID.Value);
var rows = JobBLL.JobsExist(jobIdList).AsEnumerable();

var foundIds = (from x in rows select x.Field<int>("JobID")).ToList();
var missingIds = jobIdList.Except(foundIds);

Answer 2

您需要将以下代码行添加到您的代码中。

var missingIds = JobIdList.Except(MissingList);