Re: Recursion to find an XML element - C# Discussion Boards

Re: Recursion to find an XML element [modified]

30-Dec-08 14:29

I am missing something small here. I'm writing a simple DB data transfer utility using a custom XML file as the config source (this is the first step, obtaining the DB schema).

Recursion fries my brain Dead | X|

Thanks! to anyone that can spot the IF statement I'm missing.

XML File...
<DbSync>
<Schema>
<SqlConnection Host="10.1.1.1" Database="DBName" Username="username" Password="password" />
<Output Path="C:\DbSync.schema" />
</Schema>
</DbSync>

Code...
internal class Program
{
private const string FILENAME = "Testfile.xml";

private static void Main(string[] args)
{

XmlDocument xmlDocument = new XmlDocument();
xmlDocument.Load(FILENAME);

// This line WORKS and finds the first XML Element node with the name "Schema".
XmlNode configNode = FindNode("Schema", xmlDocument.FirstChild);

// This line WORKS and finds the "SqlConnection" node in the document.
XmlNode connectionNode = FindNode("SqlConnection", configNode);

// This line WORKS and finds "NULL" because the element "Test" doesn't exist.
XmlNode nullNode = FindNode("Test", configNode);

// This line DOESN'T WORK. Element "Output" exists but it is not returning it from the document.
XmlNode outputNode = FindNode("Output", configNode);

#region Display Data
Console.Write(" ConfigNode : " + CheckValue(configNode) + Environment.NewLine);
Console.Write("ConnectionNode : " + CheckValue(connectionNode) + Environment.NewLine);
Console.Write(" NullNode : " + CheckValue(nullNode) + Environment.NewLine);
Console.Write(" OutputNode : " + CheckValue(outputNode) + Environment.NewLine);

Console.Write(Environment.NewLine + "Press Any Key" + Environment.NewLine);
Console.ReadKey(true);
#endregion
}

#region Used for displaying to console.
private static string CheckValue(object obj)
{
return obj == null ? "*** NULL ***" : "CONTAINS VALUE";
}
#endregion

// TODO: FIGURE OUT WHY I DON'T WORK IF I AM SEARCHING FOR THE 2nd, 3rd, etc... CHILDNODE. Seems to only work with the first childnode.
private static XmlNode FindNode(string nodename, XmlNode node)
{
if (node.Name == nodename)
{
return node;
}
else
{
foreach (XmlNode childNode in node.ChildNodes)
{
// Uses recursion to transverse the nodes in the Xml doc.
// I think the error is here. It is always returning the first
// child element even if there is more than 1 child element.
// I just can't figure out how to get around that (To check ALL child nodes).
// I think I need some type of if-then here but can't put my finger on it...
return FindNode(nodename, childNode);
}
}
return null;
}
}

Steven D. Foster30-Dec-08 14:52

30-Dec-08 14:52

I am using recursion instead of an XPath query because I wanted the configuration section nodes "<Schema> in this case" to be able to be placed in any XML file (At any location).

Or if anyone has an XML Element searcher function laying around. That works too.

Not Active30-Dec-08 15:55

Not Active

30-Dec-08 15:55

LnocaSteve wrote:
to be placed in any XML file (At any location).

You're just making it more difficult than it should be then. Look at the schema for web/app config files, they use a set schema to prevent this type of mess. What is your reasoning for the requirement.

only two letters away from being an asset

Steven D. Foster30-Dec-08 16:12

30-Dec-08 16:12

The program has multiple executables/services executing in different locations. I was trying to come up with a simplistic way for the application users (our sister locations) to use single XML config files for connections, and others for application settings. So if a site wanted to encrypt their connection info and/or program settings using their own encryption methodologies, it would give them the freedom to (vs say using an encrypted connection string in an App.config file).

This would also let users choose to use a single file for all of the services/executables or use individual connection information files stored separately.

Trying to avoid the redundancy in creating multiple separate config files, and instead use modular XML elements to store this information anywhere the admin chooses (by piping them via webservices, filesystem, database decrypt, etc.)

Does that help? Am I tying to implement these things in a terrible way?

Not Active30-Dec-08 16:33

Not Active

30-Dec-08 16:33

The concept is fine, I don't see a need for having your nodes in any place in the file. Having a defined schema will certainly make the configuration more maintainable. Again, look at web/app config files as an example.

You can always search for a node using XPath using the syntax "//[node name]", however, if this is a new app and using .NET 3.5 I'd use XElment or XDocument and Linq to XML.

only two letters away from being an asset

Steven D. Foster31-Dec-08 4:14

31-Dec-08 4:14

You are correct in using XPath. After seeing your and Christian Graus's comments, a simple XPath query expression definitely seems the way to go.

Thanks a ton for pointing me in the right direction (and not using my own crock pot coding to implement something that is already implemented.)

Thanks again!

Steven D. Foster30-Dec-08 16:55

30-Dec-08 16:55

private static XmlNode FindNode(string nodename, XmlNode node)
     {
         if (node.Name == nodename)
             return node;
         if (node.HasChildNodes)
             foreach (XmlNode childNode in node.ChildNodes)
             {
                 XmlNode returnNode = FindNode(nodename, childNode);
                 if (returnNode != null) return returnNode;
             }
         return null;
     }

Christian Graus30-Dec-08 18:01

Christian Graus

30-Dec-08 18:01

LnocaSteve wrote:
I am using recursion instead of an XPath query because I wanted the configuration section nodes "<schema> in this case" to be able to be placed in any XML file

That is insane. The Xpath //myNode/myChild will find those two nodes anywhere in the file. Use that syntax.

Christian Graus

Driven to the arms of OSX by Vista.

Steven D. Foster31-Dec-08 4:07

Recursion = BAD to find an XML element

31-Dec-08 4:07

AWSOME! You are absolutely correct. My recursion method is just stupid compared to the power of XPath! /bow

XPathDocument doc = new XPathDocument(filename);
XPathNavigator nav = doc.CreateNavigator();
XPathExpression expr = nav.Compile("//Schema/SqlConnection");
XPathNodeIterator iterator = nav.Select(expr);
XPathNavigator sqlConnection;
while (iterator.MoveNext())
    sqlConnection = iterator.Current.Clone();

(just a quick crude code example, I'll refine and post the full solution shortly)

I never used XPath queries in the past. I didn't know they were so powerful. Recursion is always such a resource hog.

I haven't started researching yet, but do you know of any significant drawbacks of using XPath queries, off the top of your head?

Again, Thanks!

Steven D. Foster31-Dec-08 4:45

How do i go about this... do i create a DataBind / DataSet ??? [modified]

31-Dec-08 4:45

This is a much easier way using XPath expression queries.

internal class Program
{
    private const string FILENAME = "Testfile.xml";
    private static readonly string[] SectionNames = new[] { "Schema" };
    private static readonly string[] ConfigItems = new[] { "SqlConnection", "Output" };

    private static void OutputNavigatorData(XPathNavigator navigator)
    {
        Console.WriteLine(navigator.Name);
        if (navigator.MoveToFirstAttribute())
        {
            Console.WriteLine(" - " + navigator.Name + " : " + navigator.Value);
            while (navigator.MoveToNextAttribute())
            {
                Console.WriteLine(" - " + navigator.Name + " : " + navigator.Value);
            }
        }
    }

    private static void Main(string[] args)
    {

        XmlDocument xmlDocument = new XmlDocument();
        xmlDocument.Load(FILENAME);

        XPathDocument doc = new XPathDocument(FILENAME);
        XPathNavigator nav = doc.CreateNavigator();

        foreach (var sSectionName in SectionNames)
        {
            foreach (var sConfigItem in ConfigItems)
            {
                XPathExpression expression = nav.Compile("//" + sSectionName + "/" + sConfigItem);
                XPathNodeIterator iterator = nav.Select(expression);
                while (iterator.MoveNext())
                {
                    OutputNavigatorData(iterator.Current);
                }
            }
        }
    }
}

cobalt-rose30-Dec-08 12:02

cobalt-rose

30-Dec-08 12:02

Hello i have altered my method of displaying my data since my last post and instead of a listview i am now using a datagrid as i thought it would be easier to use for what i want.

I now am stuck in terms of i do not have a clue how i am going to display the rest of the data from my table?

What i need to have is when the user clicks on a row of data e.g. 'client' all records are show in the tabbed page area?

(the picture will help to explain bettter)

Picture :

I have used a dataset to show the data when client is clicked but i dont think i can use that same dataset as it only retrieves four recods.

How can i have the four records displayed on one side of the page and then when highlighted display all infomation about the client in the seperat tabbed area?

My Code so far which displays client (when clicked) and contractor (when clicked)

using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.Data;
using System.Drawing;
using System.Linq;
using System.Text;
using System.Windows.Forms;
using MySql.Data.MySqlClient;

namespace Deroche_Consultants
{
	public partial class main_screen : Form
	{
		string dataCategory = null;
		DataSet myDataSet;

		public main_screen()
		
		{
			InitializeComponent();	  
		}

		private void client_pic_Click(object sender, EventArgs e)
			{
				ClientDataLoad();
			}

		private void client_label_Click(object sender, EventArgs e)
			{
				ClientDataLoad();
			}

		private void client_buttonBox_Click(object sender, EventArgs e)
			{
				ClientDataLoad();
			}

		private void ClientDataLoad()
		{
		   // string dataCategory = client;
			string connectionString = "Data Source=localhost" + "; Database=_consultants" + "; User ID=root" + "; Password=password;";
			MySqlConnection MySqlConn = new MySqlConnection(connectionString);
			string strSQL = ("SELECT company_id, company_name, contact_fname, contact_sname, employee_count FROM client");
			MySqlCommand mysqlCommand = new MySqlCommand(strSQL, MySqlConn);
			MySqlDataAdapter myDataAdapter = new MySqlDataAdapter(mysqlCommand);
			try
				{
					MySqlConn.Open();
					DataSet myDataSet = new DataSet();
					myDataSet.Clear();
					myDataAdapter.Fill(myDataSet, "client");
					dataGridView1.AutoGenerateColumns = true;
					dataGridView1.DataSource = myDataSet.Tables[0];
					MySqlConn.Close();
				}

			catch (Exception ex)
				{ 
					MessageBox.Show("Data Load Error "+ex.Message.ToString(),
					"Error",MessageBoxButtons.OK,MessageBoxIcon.Error);
					MySqlConn.Close();
				}
		}

		private void job_pic_Click(object sender, EventArgs e)
		{
		}

		private void job_label_Click(object sender, EventArgs e)
		{
		}

		private void job_boxButtons_Click(object sender, EventArgs e)
		{
		}
		//====================================== Contractor ======================================//

		private void contractor_pic_Click(object sender, EventArgs e)
			{
				ContractorDataLoad();
			}

		private void contractor_label_Click(object sender, EventArgs e)
			{
				ContractorDataLoad();
			}

		private void contractor_boxButton_Click(object sender, EventArgs e)
			{
				ContractorDataLoad();
			}

		private void ContractorDataLoad()
			{
			   // string dataCategory = contractor;
				string connectionString = "Data Source=localhost" + "; Database=_consultants" + "; User ID=root" + "; Password=password;";
				MySqlConnection MySqlConn = new MySqlConnection(connectionString);
				string strSQL = ("SELECT contractor_id, forename, surname, availability, daily_cost FROM contractor");
				MySqlCommand mysqlCommand = new MySqlCommand(strSQL, MySqlConn);
				MySqlDataAdapter myDataAdapter = new MySqlDataAdapter(mysqlCommand); 
			try
				{
					MySqlConn.Open();
					DataSet myDataSet = new DataSet();
					myDataSet.Clear();
					myDataAdapter.Fill(myDataSet, "contractor");
					myDataAdapter.Fill(myDataSet);
					dataGridView1.AutoGenerateColumns = true;
					dataGridView1.DataSource = myDataSet.Tables[0];
					MySqlConn.Close();
				}
				catch (Exception ex)
					{ 
						MessageBox.Show("Data Load Error "+ex.Message.ToString(),
						"Error",MessageBoxButtons.OK,MessageBoxIcon.Error);
						MySqlConn.Close();
					}
			}
		private void button1_Click(object sender, EventArgs e)
		{
			Form2 addclient = new Form2();
			addclient.Show();
		}

		private void button3_Click(object sender, EventArgs e)
		{
		}
}
}

Thanks in advance,
C~Rose

modified on Wednesday, December 31, 2008 4:36 AM

Re: How do i go about this... do i create a DataBind / DataSet ???

Not Active30-Dec-08 13:23

Not Active

30-Dec-08 13:23

What your're describing is a Master-Detail view. Try looking here for ideas http://www.codeproject.com/info/search.aspx?artkw=Master-Detail[^]

only two letters away from being an asset

Re: How do i go about this... do i create a DataBind / DataSet ???

Mycroft Holmes30-Dec-08 14:45

Mycroft Holmes

30-Dec-08 14:45

Also you need to split your app.

Shove all the DB connection stuff into another class so the connection is built only once and is local to the DB class.
Create a method for each of your load requirements that return a table (this is exactly the same code as you are using except it returns table[0])

This will start you on a better designed app that will be MUCH more readable and supportable.

Consider using stored procs instead of SQL strings (arguments for/against this are endless).

If, as Mark suggest, you want a parent child then you can move both tables into a dataset, create the relations and bind the dataset to the DGV.

Never underestimate the power of human stupidity
RAH

Re: How do i go about this... do i create a DataBind / DataSet ???

cobalt-rose1-Jan-09 13:25

cobalt-rose

1-Jan-09 13:25

Hello yer at the moment the code is all in one big chunk.... How doi go about shoving all the db connection stuff into a class so it is only built once

is this ok?:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using MySql.Data.MySqlClient;
namespace _Consultants
{
    class connectionStringClass
    {
        private void connectionString ()
        {
        string connectionString = "Data Source=localhost" + "; Database=_consultants" + "; User ID=root" + "; Password=password;";
        MySqlConnection MySqlConn = new MySqlConnection(connectionString);
        MySqlCommand mysqlCommand = new MySqlCommand(MySqlConn);
        }
    }
}

and then in the "main screen" class refer to it as a normal method right? like

connectionStringClass ();

App.config

s196675m30-Dec-08 11:34

s196675m

30-Dec-08 11:34

I am testing a dll by including it in a project.
In that project I have a App.config file where there is a sharedListeners tag with one or more custom listener.

Test is success in the case.
==============================

I am testing that dll in another project where there is a configuration file but name is not App.config instead name is xxxx.yyyy.config.
Test fail in this case. No log file generated from custom listener. Exact code inside both config file only name is different. Changing name to App.config works fine but this is not an option for me.

How can I configure the application, so that it will take the parameter from config file even though name is not App.config.

Any idea will be greately appreciated

Re: App.config

vaghelabhavesh30-Dec-08 13:08

vaghelabhavesh

30-Dec-08 13:08

Usually when you deploy the application, the app.config becomes xyz.exe.config where xyz.exe is the application executable name.

One more thing app.config should be in the same directory where the executable located.

Design time collection problem

kanchoette30-Dec-08 10:16

kanchoette

30-Dec-08 10:16

I am attempting to write my first custom component which requires a custom collection.

So far I have:

using System;
using System.Collections;
using System.ComponentModel;
using System.Windows.Forms;
using System.ComponentModel.Design;
using System.Drawing.Design;

namespace MultiColumnComboBox
{
    public partial class MultiColumnComboBox : ComboBox
    {
        
        
        public MultiColumnComboBox()
        {
            InitializeComponent();
        }

             
    }

    [Editor(typeof(ColumnCollectionEditor),UITypeEditor)]
        public ColumnCollection Columns
        {
            get { return Columns; }
            set { Columns = value; }
        }

    
    
    public class Column
    {
        #region private variables
        
        private bool _autoColumnWidth = false;
        
        #endregion

        #region public properties
        
        public bool AutoColumnWidth
        {
            get { return _autoColumnWidth; }
            set { _autoColumnWidth = value; }
        }
        
        #endregion
        
        
    }

    public class ColumnCollection : CollectionBase
    {
        public Column this[int index]
        {
            get { return (Column)List[index]; }
        }

        public void Add(Column column)
        {
            List.Add(column);
        }

        public void Remove(Column column)
        {
            List.Remove(column);
        }
    }

    public class ColumnCollectionEditor : CollectionEditor
    {
        public ColumnCollectionEditor(Type type)
            : base(type)
        {
        }

        protected override string GetDisplayText(object value)
        {
            Column item = new Column();
            item = (Column)value;
            return base.GetDisplayText(string.Format("{0}", item.AutoColumnWidth));
        }
    }
}

The compiler does not like the section:

[Editor(typeof(ColumnCollectionEditor),UITypeEditor)]
        public ColumnCollection Columns
        {
            get { return Columns; }
            set { Columns = value; }
        }

it highlights the ColumnCollection reference, but I don't understand why. Can an experienced C# coder please point me in the right direction of where I am failing?

It's hard being a simpleton Sniff | :^)

Wendelius30-Dec-08 10:44

Wendelius

30-Dec-08 10:44

kanchoette wrote:
The compiler does not like the section
it highlights the ColumnCollection reference

What is the error you get at compilation?

The need to optimize rises from a bad design.My articles[^]

kanchoette30-Dec-08 11:28

kanchoette

30-Dec-08 11:28

I get

"Expected class, delegate, enum, interface, or struct" and the ColumnCollection reference is highlighted (red wiggly line)

Wendelius30-Dec-08 11:41

Wendelius

30-Dec-08 11:41

It's been awhile since I last worked with editors but if I recall correctly, you should use typeuf on the second parameter also. And when using two types, the second parameter is used for the base class so perhaps something like:

[Editor(typeof(ColumnCollectionEditor), typeof(CollectionEditor))]

Does that help or change the error in anyway?

The need to optimize rises from a bad design.My articles[^]