返回完整结果linq分组查询

Question

I'm trying to group and still retrieve all the data in the table. I'm still pretty new to Linq and can't seem to tell what I'm doing wrong. I not only want to group the results but I still want to retrieve all the columns in the table. Is this possible?

    (from r in db.Form
     orderby r.CreatedDate descending
     group r by r.Record into myGroup
     where myGroup.Count() > 0
     where (r.CreatedDate > lastmonth)
     where r.Name == "Test Name"
     select new { r, myGroup.Key, Count = myGroup.Count() }
    )

Some how "r" loses its context or since I grouped "r" it has been replaced. Not sure.

Answer 1

You need to split your task into two steps to accomplish what you want.

Group data

var groupedData = db.Form.Where(item=>item.CreatedDate > lastMonth && item.Name == "Test Name")
                    .OrderByDescending(item=>item.item.CreatedDate)
                    .GroupBy(item=>item.Record)
                    .Select(group => new {Groups = group, Key = group.Key, Count = group.Count()})
                    .Where(item => item.Groups.Any());

From the grouped data select Form elements

var formElements = groupedData.SelectMany(g => g.Groups).ToList();

Answer 2

Since you're filtering on individual records, you should filter them before grouping rather than after:

(
    from r in db.Form
    where r.CreatedDate > lastMonth)
    where r.Name == "Test Name"
    orderby r.CreatedDate descending
    group r by r.Record into myGroup
    where myGroup.Count() > 0
    select new { Groups = myGroup, myGroup.Key, Count = myGroup.Count() }
)
// Groups is a collection of db.Form instances