Question

Im trying to use LINQ to sort data that is going to be used into a report. The report strucuture looks like this:

---

Developer name

Date | Hours | Project Name | Week Ending
Date | Hours | Project Name | Week Ending
Date | Hours | Project Name | Week Ending

Developer name

Date | Hours | Project Name | Week Ending
Date | Hours | Project Name | Week Ending

Developer name

Date | Hours | Project Name | Week Ending
Date | Hours | Project Name | Week Ending
Date | Hours | Project Name | Week Ending

---

I am bringing all that data from a .dbml file. For such sorting i have this linq query:

DataClasses1DataContext context = new DataClasses1DataContext();
        System.Data.Linq.ISingleResult<s_SummaryReportResult> res = context.s_timesheet_SummaryReport(startDate, endDate);

        var orb = from c in res
                  group c by c.developer
                  into devgroup
                  select new 
                  {   
                      Dev = devgroup.Key,
                      devData = from o in res
                                      select new {
                                        o.Date,
                                        o.Hours,
                                        o.projectname,
                                        o.week_ending
                                      }};

IDictionary dic_orb = orb.ToDictionary(result => result.Dev.ToString(), result => result.devData);


        foreach (KeyValuePair<string, object> item in dic_orb)
        {
          object brr =  item.Value;
        }

Sadly, on the foreach step i get an “InvalidCastException”.

Any clues in how i can resolve that foreach, or in a sense, how to group better that LINQ query?

Thanks in advance.

Answer 1

dic_orb is a Dictionary<string, IEnumerable<'a>> where 'a is the anonymous type defined in your query. The type KeyValuePair<string, IEnumerable<'a>> is not convertible to KeyValuePair<string, object> hence the invalid cast. The fix is to declare item using var in your foreach loop:

foreach (var item in dic_orb)
{
    object brr =  item.Value;
}

Since item.Value is an IEnumerable<'a> you can iterate it using

var brr = item.Value;
foreach(var b in brr)
{
}

If you just want to iterate all nested collections you can use

foreach(var b in dic_orb.SelectMany(kvp => kvp.Vaue))
{
}