IGrouping does not contain a definition for Sum

Question

Would anyone have an idea what's up here? I'm loading an XML file, parsing it and using LINQ to get some summary info. Here's the XML document:

<?xml version="1.0" encoding="utf-8"?>
<root>
  <Ticker>
    <Name>MSFT</Name>
    <PurchaseDate>
      2009-01-01
    </PurchaseDate>
    <Shares>44</Shares>
  </Ticker>
  <Ticker>
    <Name>MSFT</Name>
    <PurchaseDate>
      2009-03-01
    </PurchaseDate>
    <Shares>33</Shares>
  </Ticker>
  <Ticker>
    <Name>GOOG</Name>
    <PurchaseDate>
      2009-03-01
    </PurchaseDate>
    <Shares>122</Shares>
  </Ticker>
  <Ticker>
    <Name>AAPL</Name>
    <PurchaseDate>
      2019-03-01
    </PurchaseDate>
    <Shares>89</Shares>
  </Ticker>
</root>

My code:

var xmlStr = File.ReadAllText("ClientInfo.xml");
var Summary = XElement.Parse(xmlStr);
var data = from acct in Summary.Elements("Ticker")
       select new
       {
           Ticker = (string)acct.Element("Name"),
           Shares = (int)acct.Element("Shares")
       };

var groupedDataByTicker = from acct in data
                          group acct by acct.Ticker into g
                          select new
                          {
                              Ticker = g.Key,
                              Shares = g.Sum(),
                          };

Works fine but when I add the g.Sum() bit I get this message:

'IGrouping>' does not contain a definition for 'Sum' and the best extension method overload 'Queryable.Sum(IQueryable)' requires a receiver of type 'IQueryable'

I can't make sense of it, what am I doing wrong?

Answer 1

In your code, you are trying to find the sum of the group itself.

Instead, you should be summing by the Shares property:

var groupedDataByTicker = from acct in data
                          group acct by acct.Ticker into g
                          select new
                          {
                              Ticker = g.Key,
                              Shares = g.Sum(row => row.Shares),
                          };