使用XML节点作为页面列表。 添加编号的XML节点，然后重新排序。 Visual C＃

Question

I was hoping that someone could help me with roadblock I've hit with my project. I am beginner to programming in general and I'm learning C# (WinForms). I'm making a simple text editor. I have a rich text file and a XML file to store other information. Inside the XML file I have a pages node that I want to use to store line numbers. I have a button that will scroll a rich text box to the next page's line number stored in the XML file. For example:

<pages>
  <page1>0</page1>
  <page2>32</page2>
</pages>

I have another button that will add a page to the pages node. When adding the new page, I need my app to add the new node with the correct name and in the correct place in the pages node. For example, Adding a new page for line 16, the file will then look like this;

<pages>
  <page1>0</page1>
  <page2>16</page2>
  <page3>32</page3>
</pages>

I have got as far a adding a new node into the XML file and getting the selected line number, but I can't figure out the next step. Firstly, How do I get the new node's (in the case above, page2) to have the correct number in its name? If you clicked on the add page button again on line 8, it would become page2, line 16 would become page3, line 32 would become page4 and so on. See comment 1 in following code which is from the main form.cs file.

string xmlFile = @"C:/test.xml";

private void bottomBarAddPageButton_Click(object sender, EventArgs e)
    {
        int cursorPosition = mainTextbox.SelectionStart;
        int lineIndex = mainTextbox.GetLineFromCharIndex(cursorPosition);
        XmlNode pagesNodes = XmlReader.SelectSingleNode("root/pages");
        XmlNode pageNodeCreate = XmlReader.CreateElement("page"); // Comment 1: Needs to add correct page number here 
        pageNodeCreate.InnerText = Convert.ToString(lineIndex);
        pagesNodes.AppendChild(pageNodeCreate);
        XmlReader.Save(xmlFile);
    }

The following is what the XML file currently looks like. Clicking bottomBarAddPageButton adds a new node called page with the inner text as the selected line number (lineIndex).

<root>
  <otherNodes>
  <pages>
    <page>0</page>
    <page>28</page>
    <page>32</page>
    <page>8</page>
    <page>76</page>
    <page>10</page>
  </pages>
</root>

Secondly, After a new node is added, how do I then reorder all the child nodes within pages so the XML file looks like this?

<root>
  <otherNodes>
  <pages>
    <page1>0</page1>
    <page2>8</page2>
    <page3>10</page3>
    <page4>28</page4>
    <page5>32</page5> 
    <page6>76</page6>       
  </pages>
</root>

I also need to be able to do the reverse when a page is removed. For example, if one clicks on the remove page button on line 19 of the rich text box, page3 (node containing line 10) would be removed so that page2 would be from line 8 through to line 27. page3 would be from line28 through to line 32 and so on.

As I said at the start, I beginner with C# and I have no idea how to do this, what the best method is or if I'm going down that right road. So I was hoping that someone out there would be able to help me. I hope I have explained what I'm trying to do clearly enough and that my question makes sense.

Thank you so much for your time and with any help.

Morgan

PS Please forgive me for posting such a huge question but I wanted to give as much info as I could.

Answer 1

I think best approach would be to have class named Page and list of those pages. Then, you can serialize class to xml (and deserialize xml to class again). That way you can manipulate Page collection without fiddling with xml.

I would make it like this:

Classes

[Serializable]
[XmlRoot("root")]
public class Data
{

    [XmlArray("Pages")]
    [XmlArrayItem(ElementName = "Page", Type = typeof(Page))]
    public List<Page> Pages { get; set; }

    //add as many properties as needed
    public int SomeIntNode { get ; set; }

    //using [XmlElement] attribute, you can change how the element will be named in xml 
    [XmlElement("otherName")]
    public string Name { get; set; }

}

[Serializable]
public class Page
{
    [XmlAttribute]
    public int Value { get; set; }

    //you can add additional attributes if needed.
    //just make a property and add [XmlAttribute] attrib, like this:
    //[XmlAttribute]
    //public sting SomeText { get; set; }
    //so it will be written as <Page Value="123" SomeText="abc" />
}

Class Data is just container which contains Pages collection. You can add addition properties to Data class if you also want them serialized.

Page is class that contains value (row in your RichTextBox ).

Attributes like [XmlArray("Pages")] and [XmlArrayItem(ElementName = "Page", Type = typeof(Page))] are used as additional description for serializer (class that converts and writes data to xml format). First tells serializer how to name collection and second how to name an element and it's type. Attribute [Serializable] tells that class can be serialized.

Usage

Make an instance of Data class and add pages to it's Pages collection. Write data, and load it again when necessary. Once loaded, you can iterate thru Pages by index or using foreach or using for loop. Then, you can add one or more pages to collection and sort it again.

public void Test()
{ 

    //create data and write it to xml
    CreateData();
    //load data from xml
    Data data = LoadData();
    //iterate thru collection if needed
    foreach (Page page in data.Pages)
    {
        System.Diagnostics.Debug.WriteLine(string.Format("page number {0}, value: {1}",(data.Pages.IndexOf(page) + 1), page.Value));
        //or, you can write to debug window like this:
        //System.Diagnostics.Debug.WriteLine("page number " + (data.Pages.IndexOf(page) + 1).ToString() + ", value: " + page.Value.ToString());
        //or fill some listbox
        //listBox1.Items.Add("page number " + (data.Pages.IndexOf(page) + 1).ToString() + ", value: " + page.Value.ToString());
        //...
    }
    //access second page (by index... index 1 is page 2)
    var specificPage = data.Pages[1];
    //add additional page and sort it by value
    data.Pages.Add(new Page() { Value = 15 });
    data.Pages.OrderBy(x => x.Value);
    //write again if needed
    WriteToXml(data);

}

private void CreateData()
{
    Data data = new Data();
    data.Pages = new List<Page>();             
    data.Pages.Add(new Page() { Value = 10 });
    data.Pages.Add(new Page() { Value = 20 });
    data.Pages.Add(new Page() { Value = 30 });

    //other properties
    data.SomeIntNode = 100;
    data.Name = "here is name";

    WriteToXml(data);

}

private void WriteToXml(Data data)
{
    XmlSerializer xSer = new XmlSerializer(typeof(Data));
    using (TextWriter writer = new StreamWriter(@"c:\temp\pages.xml"))
    {
        XmlSerializerNamespaces ns = new XmlSerializerNamespaces();
        ns.Add("", "");
        xSer.Serialize(writer, data, ns);
    }
}

private Data LoadData()
{
    XmlSerializer xSer = new XmlSerializer(typeof(Data));
    using (TextReader reader = new StreamReader(@"c:\temp\pages.xml"))
    {
        return xSer.Deserialize(reader) as Data;
    }
}

xml data (EDIT: updated because of new properties and with new root name)

<?xml version="1.0" encoding="utf-8"?>
<root>
  <Pages>
    <Page Value="10" />
    <Page Value="20" />
    <Page Value="30" />
    <Page Value="15" />
  </Pages>
  <SomeIntNode>1000</SomeIntNode>
  <otherName>here is name</otherName>
</root>

If you have some questions, feel free to ask.

EDIT: renamed data element to root (to be more like your sample) and added new properties in Data class to show how other data can be added (look in CreateData() ).