using GetElementsByTagName with multi tags

Question

I have many tags in my XML

is there a way I can select all tags by name at once something like

xmlnode = xmldoc.GetElementsByTagName("group1:White, group2:Blue, group3:Brown");

Bandook · Accepted Answer

Ok. so as mentioned by Sajid in your other post - the group1 and group2 are not declared in the posted XML. Ignoring that for now (you'll need to provide us means on how those groups have been declared or manage it by yourself), there is a way to do what you need - instead of your method to get element by the multiple names, you can get all children of a specific node by -

using System.Xml.Linq;    
XDocument xdoc = XDocument.Parse(xmlString);
List elements = xdoc.Descendants("specificNodeName").DescendantNodes().OfType();

If you want all XElements within the root -

List elements = xdoc.Root.DescendantNodes().OfType();

Doing this will also give you the "cas:Null" tag, but you can ignore it with a simple condition.

If you require to get the attributes, you can then -

foreach(XElement element in elements)
{
    string attrValue = element.Attribute("attributeNameHere").Value;
}

Also, if you want all the XElement Names as a list of strings, then you can -

List elementNames = xdoc.Root.DescendantNodes().OfType().Select(x => x.Name).ToList()

This will give you a list of strings - "Black", "White", "Pink" etc.

If you want further idea on getting element names within another element or getting unique values have a look at my other post - How to get nodes from XML file without its attribute and put to a List of string

Note - you might need to manage namespace - there is plenty of help on that in SO e.g. How to parse XML with namespace

Hope this helps.

Edit

If you still want to do it in your style you'll need to create an extension method, something to this effect -

public static class MyXmlExtensions
{
    public static List GetElementsByName (this XElement main, List requiredElements)
    {
        List ElementsByName = new List();
        foreach(string reqElement in requiredElements)
        {
            List nodes = main.Descendants(reqElement);
            ElementsByName.AddRange(nodes);
        }
        return ElementsByName;
    }     
}

You can then use that -

List requiredElements = new List () { "group1:White", "group2:Blue", "group3:Brown" };
List myElements = xdox.Root.GetElementsByName(requiredElements);

If you do not want to create a list and pass it, you can directly use the params keyword in your extension method - https://learn.microsoft.com/en-us/dotnet/csharp/language-reference/keywords/params if you need help with that let me know

using GetElementsByTagName with multi tags

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