Question

I get the following:

Cannot implicitly convert type System.Collections.Generic.Dictionary<System.DateTime?,double?> to System.Collections.Generic.Dictionary<System.DateTime,double>

When I try to use a stored procedure within Entity Framework

Here is the code that I have:

    private Dictionary<DateTime, double> GetData(string columnName)
    {
        return db.SysReading(columnName, Convert.ToString(LocId)).
            ToDictionary( a => a.DateCollected, a => a.ElementReading);

    }

I am using a call to a Stored Procedure called SysReading. When I convert it to a dictionary, the return type is nullable which I do not want.

Answer 1

Well it sounds like a.DateCollected is a DateTime? property instead of DateTime. If you believe all keys will have values, you can just use:

private Dictionary<DateTime, double> GetData(string columnName)
{
    return db.SysReading(columnName, Convert.ToString(LocId))
             .ToDictionary(a => a.DateCollected.Value, a => a.ElementReading);
}

Or you could filter and then convert:

private Dictionary<DateTime, double> GetData(string columnName)
{
    return db.SysReading(columnName, Convert.ToString(LocId))
             .Where(a => a.DateCollected.HasValue)
             .ToDictionary(a => a.DateCollected.Value, a => a.ElementReading);
}

Alternatively, change your method to return a Dictionary<DateTime?, double>.