C＃无法从对象列表中获取值

Question

I have my main Program class that calls the StronyElementuStrukt procedure

List<object> monthlyPages = new List<object>();
monthlyPages =  StronyElementuStrukt(loginGuid, "8B35134E10A8432DB1A8C06A58427988");

Here is the procedure - a method that builds a list of xml nodes and returns it to the main Program class:

public static List<object> StronyElementuStrukt(string LoginGUID, string LinkGUID)
{
    List<object> listPages = new List<object>();

    XmlDocument document = new XmlDocument(); // tworzenie nowego obiektu - dokument xml z odpowiedzia serwera
    document.LoadXml(response.Result); //wczytywanie xmla z odpowiedzia serwera do obiektu
    XmlNode pageNode = document.SelectSingleNode("/IODATA/PAGES/PAGE"); //deklaracja noda xmlowego

    if (pageNode != null) //jeżeli PAGE node istnieje
    {
        XmlNodeList nodeList = document.SelectNodes("//PAGE");

        foreach (XmlNode node in nodeList)
        {
            listPages.Add(node);
        }
        return listPages;
    }
}

In the main Program Class I need to pick up value of xml id attribute, I'm trying to do it like this:

foreach (object monthlyPage in monthlyPages)
{
    Console.WriteLine(monthlyPage.Attributes["id"].Value);
}

The problem is that when I try to get the id I get the following error:

Error 6 'object' does not contain a definition for 'Attributes' and no extension method 'Attributes' accepting a first argument of type 'object' could be found (are you missing a using directive or an assembly reference?)

Could you tell me how to reach to xml attributes in the foreach loop, please? Please ask if something is not clear enough.

Answer 1

Change the method to return a List<XmlNode> .

public static List<XmlNode> StronyElementuStrukt(string LoginGUID, string LinkGUID)
{
    List<XmlNode> listPages = new List<object>();

    XmlDocument document = new XmlDocument(); // tworzenie nowego obiektu - dokument xml z odpowiedzia serwera
    document.LoadXml(response.Result); //wczytywanie xmla z odpowiedzia serwera do obiektu
    XmlNode pageNode = document.SelectSingleNode("/IODATA/PAGES/PAGE"); //deklaracja noda xmlowego

    if (pageNode != null) //jeżeli PAGE node istnieje
    {
        XmlNodeList nodeList = document.SelectNodes("//PAGE");

        foreach (XmlNode node in nodeList)
        {
            listPages.Add(node);
        }
    }

    return listPages;
}

Then this will work.

List<XmlNode> monthlyPages = StronyElementuStrukt(
    loginGuid, 
    "8B35134E10A8432DB1A8C06A58427988");

foreach (XmlNode monthlyPage in monthlyPages)
{
    Console.WriteLine(monthlyPage.Attributes["id"].Value);
}

Note that you could just change the foreach to declare monthlyPage as XmlNode instead of object and it will do a cast for you. But it is better to be specific with the types you are putting into a generic collection.

Answer 2

I changed all occurences from List<object> to List<XmlNode> . So the code now looks like this: Main Program:

List<XmlNode> monthlyPages = new List<XmlNode>();
monthlyPages =  StronyElementuStrukt(loginGuid, "8B35134E10A8432DB1A8C06A58427988");
foreach (XmlNodemonthlyPage in monthlyPages)
{
    Console.WriteLine(monthlyPage.Attributes["id"].Value);
}

Procedure:

    public static List<XmlNode> StronyElementuStrukt(string LoginGUID, string LinkGUID)
{
        List<XmlNode> listPages = new List<XmlNode>();

        XmlDocument document = new XmlDocument(); // tworzenie nowego obiektu - dokument xml z odpowiedzia serwera
        document.LoadXml(response.Result); //wczytywanie xmla z odpowiedzia serwera do obiektu
        XmlNode pageNode = document.SelectSingleNode("/IODATA/PAGES/PAGE"); //deklaracja noda xmlowego

        if (pageNode != null) //jeżeli PAGE node istnieje
        {
            XmlNodeList nodeList = document.SelectNodes("//PAGE");

            foreach (XmlNode node in nodeList)
            {
                listPages.Add(node);
            }
            return listPages;
        }
    }