Querying an Xml Document for elements using Linq

I am using XDocument to work with XML data. My Xml has the following structure

<Info>
 <ProductDetails>
    <ProductDetail>
      <ProductId>123</ProductId>
      <ProductName>Test</ProductName>
      <ProductType>1</ProductType>
      <AccountDetails>
        <AccountType>Single</AccountType>
        <AccountDetail>
          <AccountId>8564</AccountId>
        </AccountDetail>
      </AccountDetails>
    </ProductDetail>
  </ProductDetails>
</Info>

I want to retrieve the AccountDetails section in the XML based on a particular element Id and then replace it with some other XML content. I tried something like 

xdoc.Root.Element("ProductDetails").Element("ProductDetail").Element("ProductId").Value

What will be the best way to achieve this

Jon Skeet
people
quotationmark

It sounds like you want to find the first ProductDetail element with a given product ID. This would do the trick for that:

public XElement FindProduct(XDocument doc, int id)
{
    return doc.Descendants("ProductId")
              .Where(pid => (int) pid == id)
              .Select(pid => pid.Parent)
              .FirstOrDefault();
}

This will return null if it doesn't find the relevant product. Note that it will not detect the presence of multiple products with the same ID.

people

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