Question

I am new to .NET and I am having some trouble implementing queries in LINQ to XML.

I have a XML file in a strange format:

<calendar>
    <event>
        <amount>1200</amount>
        <age>40</age>
        <country>FR</country>

        <amount>255</amount>
        <age>16</age>
        <country>UK</country>

        <amount>10524</amount>
        <age>18</age>
        <country>FR</country>

        <amount>45</amount>
        <age>12</age>
        <country>CH</country>
    <event>
    <event>
        <amount>1540</amount>
        <age>25</age>
        <country>UK</country>

        <amount>255</amount>
        <age>31</age>
        <country>CH</country>

        <amount>4310</amount>
        <age>33</age>
        <country>FR</country>

        <amount>45</amount>
        <age>17</age>
        <country>FR</country>
    <event>
</calendar>

From this file I want to compute the sum of every <amount> element value, where <age> is greater than ’20’ and <country> is either ‘FR’ or ‘CH’.

This operation is independent of the tag <event> (all <amount> elements that check the above conditions should be summed, whether they’re under the same or different <event> elements).

My problem is that I have no element tag that groups <amount>, <age> and <country> together… (I can’t change the XML format, I’m consuming it from a Web Service I can’t access).

If I had an hypothetical <transfer> tag grouping these triples together, I think the code would be simply:

XElement root = XElement.Load("calendar.xml");
IEnumerable<XElement> sum =
    from trf in root.Elements("events").Elements("transfers")
    where (decimal) trf.Element("age") > 20 &&
          ((string) trf.Element("Country") == "FR" ||
       (string) trf.Element("Country") == "cH")
    select trf.Element("Amount").Sum();

Should I programatically group these elements? Thanks in advance!

Answer 1

Try this:

var xe = XElement.Load(@"calendar.xml");
var langs = new List<string> { "FR", "CH" };

var sum = xe.Descendants("amount")
    .Where(e =>
           Convert.ToInt32(e.ElementsAfterSelf("age").First().Value) > 20 &&
           langs.Any(l => l == e.ElementsAfterSelf("country").First().Value))
    .Select(e => Convert.ToDouble(e.Value)).Sum();

I have tested the code. You also have to make sure that amount element must be the first element in the group.