Question

I have been struggling with the XMLReaderClass in c# for some time now and just can’t seem to get the concept. Basically I want to loop through the XML File and if the category in the xml doc is the same as the category I have passed it in, I want to add its name to a List.

here is the xml

<?xml version="1.0" encoding="utf-8" ?>
<!-- Do not modify this xml file. -->
<Products>
    <product category="Food"  name="Baking potatoes" />
    <product category="Food" name="Chicken fillet" />
    <product category="Food" name="Chocolate gateau" />
    <product category="Food" name="Madras curry sauce" />
    <product category="Food" name="Organic carrots" />
    <product category="Food" name="Semi-skimmed milk" />
    <product category="Home" name="Washing powder" />
    <product category="Home" name="Rubber gloves" />
    <product category="Home" name="Spray wax" />
    <product category="Home" name="Dish soap" />
    <product category="Pet" name="Cat food" />
    <product category="Pet" name="Dog food" />
    <product category="Pet" name="Collar" />
    <product category="Pet" name="Leash" />
</Products>

and here is my code I have started to work on but didn’t get very far 🙁

public ReadOnlyCollection<string> GetProductsByCategory(string category)
    {
        List<string> returnList = new List<string>();

        using (XmlReader productsReader = GetProductsReader())
        {


            productsReader.MoveToContent();
            while (productsReader.Read())

                if(productsReader.NodeType == XmlNodeType.Element)
            {
                if (productsReader)
                {
                    if productsReader
                }
            }

        }

        return new ReadOnlyCollection<string>(returnList);
    }

Answer 1

Using an XmlReader here will just be a pain to use. Use LINQ to XML here using that API instead, it will make your life easier.

public static ReadOnlyCollection<string> GetProductsByCategory(string category)
{
    using (var reader = GetProductsReader())
    {
        var doc = XDocument.Load(reader);
        var results = doc.Element("Products")
            .Elements("product")
            .Where(e => (string)e.Attribute("category") == category)
            .Select(e => (string)e.Attribute("name"))
            .ToList();
        return new ReadOnlyCollection<string>(results);
    }
}

If for whatever reason you still wish to use the XmlReader, you could read it like this:

public static ReadOnlyCollection<string> GetProductsByCategory(string category)
{
    var results = new List<string>();
    var settings = new XmlReaderSettings
    {
        IgnoreWhitespace = true,
        IgnoreComments = true,
    };
    using (var reader = XmlReader.Create(GetProductsReader(), settings))
    {
        reader.MoveToContent();
        reader.ReadStartElement("Products");
        do
        {
            if (reader.IsStartElement("product"))
            {
                if (reader.MoveToFirstAttribute())
                {
                    string currentCategory = null;
                    string currentName = null;
                    do
                    {
                        switch (reader.Name)
                        {
                        case "category":
                            currentCategory = reader.ReadContentAsString();
                            break;
                        case "name":
                            currentName = reader.ReadContentAsString();
                            break;
                        }
                    } while (reader.MoveToNextAttribute());
                    if (currentCategory == category && currentName != null)
                        results.Add(currentName);
                }
            }
        } while (reader.ReadToNextSibling("product"));
    }
    return new ReadOnlyCollection<string>(results);
}