Problems with Linq/XML query-CodePudding

So I have this XML file:

<student_update date="2022-04-17" program="PMM" checksum="20021621">
    <transaction>
        <program>PMM</program>
        <student_no>10010800</student_no>
        <course_no>*</course_no>
        <registration_no>111</registration_no>
        <type>2</type>
        <grade>100</grade>
        <notes>Update Grade Test</notes>
    </transaction>
    <transaction>
        <program>PMM</program>
        <student_no>10010821</student_no>
        <course_no>M-50033</course_no>
        <registration_no>*</registration_no>
        <type>1</type>
        <grade>*</grade>
        <notes>Register Course Test</notes>
    </transaction>
</student_update>

And I am trying to run a query against it where the result set should only include transaction elements whose type element is 1 and grade element is “*”, OR whose type element is 2 and grade element is between 0 and 100 inclusive.

The query I have come up with so far is this:

XDocument xDocument = XDocument.Load(inputFileName);

  XElement root = xDocument.Element("student_update");

   IEnumerable<XElement> transactionElements = xDocument.Descendants().Where(x => x.Name == "transaction");

    IEnumerable<XElement> gradeForCourseElement = numTypeElement.Where(x => Int32.Parse(x.Element("type").Value) == 1 && x.Element("grade").Value == "*" ||
                                                                       Int32.Parse(x.Element("type").Value) == 2 && Int32.Parse(x.Element("grade").Value) <= 100);

but it doesn't seem to be liking my way of doing this. I am looking for some advice on how to achieve the requested results. Thanks!

CodePudding user response：

The main thing you've probably missed is that first of all you have to get all descendand elements of the document. Assuming that we want to query from a root element of a document, the code below should work.

This part int.Parse(_.Element("grade")?.Value) <= 100 must be written more carefully.

var xml = "%your xml goes here%";

using (var textReader = new StringReader(xml))
{
    using (var xmlTextReader = new XmlTextReader(textReader))
    {
        var xDoc = XDocument.Load(xmlTextReader);
        var result = xDoc.Descendants()
            .Where(_ => _.Name.LocalName == "transaction"
            &&
            (
                _.Element("type")?.Value == "1" && _.Element("grade")?.Value == "*"
                 ||
                 _.Element("type")?.Value == "2" && int.Parse(_.Element("grade")?.Value) <= 100
            )
            )
            .ToList();
    }
}