Convert a standard EF list to a nested JSON - asp.net

Question

I have a WEB Method in my ASPX page that retrieves a List from SQL DB using Entity Framework.
Using rep As New RBZPOSEntities
q = rep.getSalesByLocation(fDate, tDate).ToList
End Using
Thereafter i use javascriptserializer to convert this list into a JSON string
Dim jss As JavaScriptSerializer = New JavaScriptSerializer()
Dim json As String = jss.Serialize(q)
So the above works great and i can use AJAX on the client side to display the results successfully.
The problem i am having now is converting a Flat List into a Nested JSON string.
So consider a list like:
locationName as string
MonthName as string
totalAmount as string
Which needs to be converted into a JSON like this:
[{locationName:'Tokyo',totalAmount:[100,200,300,400]},
{locationName:'New York',totalAmount:[500,600,700,800]}]
So the totalAmount values in the above case correspond to totalAmounts for a Location for a specific month. E.g. Tokyo total amount in January is 100, in February is 200 and etc.
What i can do:
I can create a nested list and populate it with results from EF and then serialize to JSON.
What i am asking:
Is there any other cleaner way to do it.
Thank you

Answer 1

As Todd has already said you need to convert your flat list into a list of another intermediate type. Let's call your existing Type the "InputType" and the Type you want the "OutputType"
Public Class InputClass
Public locationName as String
Public MonthName as String
Public totalAmount as String
End Class
Public Class OutputClass
Public LocationName As String
Public TotalAmount As List(Of String)
Public Sub New(groupedInputClass As IGrouping(Of String, InputClass))
LocationName = groupedInputClass.Key
TotalAmount = groupedInputClass.Select(Function(x) x.totalAmount).ToList()
End Sub
End Class
Then all you need to do is transform a List of InputType into a List of OutputType which is really easy with LINQ.
Public Class MappingHelper
Public Function Map (inputList as List(Of InputClass)) As List(Of OutputClass)
Dim groupedByLocation = inputList.GroupBy(Function(k) k.LocationName)
Dim nestedLocations = groupedByLocation.Select(Function(x) new OutputClass(x)).ToList()
Return nestedLocations
End Function
End Class

Answer 2

If you use an intermediate type, it may be helpful. Something like:
class RbzposInfo {
public string Location {get;set;}
public List<MonthlyRevenue> Monthlies {get;set;}
}
class MonthlyRevenue {
public string Month {get;set;}
public int Revenue {get;set;}
}
var result = new List<RbzposInfo>();
foreach (var r in q) { // q from your code
var info = new RbzposInfo();
// TODO: put r values into info.
result.Add(info);
}
Dim json As String = jss.Serialize(result);
(PS, sorry I mixed .NET languages on you. My code is C#.)