Reading + Writing XML

Im pretty n00bish so im sure it's just a dumb mistake I did. But I can't read the xml and then write something on it.

static string LoadXML(String TheParent, String TheChild)
{
System.IO.StreamReader sr = new System.IO.StreamReader(@"SP.xml");
System.Xml.XmlTextReader xr = new System.Xml.XmlTextReader(sr);
System.Xml.XmlDocument SP = new System.Xml.XmlDocument();
SP.Load(xr);
System.Xml.XmlNodeList SPParent = SP.SelectNodes("XMLDoc/" + TheParent);
System.Xml.XmlNode SPChild = SPParent.Item(0).SelectSingleNode(TheChild);
return SPChild.InnerText;
}

public void WriteXML(String TheParent, String TheChild, String TheValue)
{
System.IO.StreamReader sr = new System.IO.StreamReader(@"SP.xml");
System.Xml.XmlTextReader xr = new System.Xml.XmlTextReader(sr);
System.Xml.XmlDocument SP = new System.Xml.XmlDocument();
SP.Load(xr);
System.Xml.XmlNodeList SPParent = SP.SelectNodes("XMLDoc/" + TheParent);
System.Xml.XmlNode SPChild = SPParent.Item(0).SelectSingleNode(TheChild);

System.Xml.XmlTextWriter Writer = new System.Xml.XmlTextWriter(TheValue, System.Text.UTF8Encoding.UTF8);
SP.WriteTo(Writer);
Writer.Flush();
}






private void button1_Click(object sender, EventArgs e)
{
int TestMe = Int32.Parse(LoadXML("Main", "Subjects")) + 1;
WriteXML("Main", "Subjects", TestMe.ToString());
Label1.Text = LoadXML("Main", "Subjects");
}


There are no errors, I can build it and perform the button click just fine. The XML looks like this:

<XMLDoc>
<Main>
<Subjects>3</Subjects>
</Main>
</XMLDoc>



When I call the button click, Label1.Text says there is still 3 for the subject. I also tried:

private void button1_Click(object sender, EventArgs e)
{
int TestMe = 15;
WriteXML("Main", "Subjects", TestMe.ToString());
Label1.Text = LoadXML("Main", "Subjects");
}


And it still shows 3 in Label1.text.

Anyone?

Ok I played around with it some more.. Came out to:

static string LoadXML(String TheParent, String TheChild)
{
System.IO.StreamReader sr = new System.IO.StreamReader(@"SP.xml");
System.Xml.XmlTextReader xr = new System.Xml.XmlTextReader(sr);
System.Xml.XmlDocument SP = new System.Xml.XmlDocument();
SP.Load(xr);
System.Xml.XmlNodeList SPParent = SP.SelectNodes("XMLDoc/" + TheParent);
System.Xml.XmlNode SPChild = SPParent.Item(0).SelectSingleNode(TheChild);
return SPChild.InnerText;
}

public void WriteXML(String TheParent, String TheChild, String TheValue)
{
System.IO.StreamReader sr = new System.IO.StreamReader(@"SP.xml");
System.Xml.XmlTextReader xr = new System.Xml.XmlTextReader(sr);
System.Xml.XmlDocument SP = new System.Xml.XmlDocument();
SP.Load(xr);
System.Xml.XmlNodeList SPParent = SP.SelectNodes("XMLDoc/" + TheParent);
System.Xml.XmlNode SPChild = SPParent.Item(0).SelectSingleNode(TheChild);
System.Xml.XmlTextWriter Writer = new System.Xml.XmlTextWriter("SP.xml", System.Text.UTF8Encoding.UTF8);
Writer.WriteStartElement("XMLDoc");
Writer.WriteStartElement(TheParent);
Writer.WriteStartElement(TheChild, TheValue);
SPChild.WriteTo(Writer);
Writer.Flush();
}






private void button1_Click(object sender, EventArgs e)
{
int TestMe = 15;// Int32.Parse(LoadXML("Main", "Subjects")) + 1;
WriteXML("Main", "Subjects", TestMe.ToString());
QsStr.Text = LoadXML("Main", "Subjects");
}



XML is in the debug and it looks like:

<XMLDoc>
<Main>
<Subjects>3</Subjects>
</Main>
</XMLDoc>


So now it's highlighting the line:

System.Xml.XmlTextWriter Writer = new System.Xml.XmlTextWriter("SP.xml", System.Text.UTF8Encoding.UTF8);



And it says that, "The process cannot access the file ... because it is being used by another process." ... Any ideas?

have you tried using XmlDocument and XmlElement?

to load ( i find this easier to use ) :)

Code:

---

XmlDocument doc = new XmlDocument();
doc.Load(filename);

---

i modified your code a bit

Code:

---


private string LoadXML(String TheParent, String TheChild )
{
                XmlDocument doc = new XmlDocument();
                doc.Load(@"SP.xml");
 
                XmlNode node = doc.DocumentElement;
                string data = "";
                if( node.LocalName == TheParent )
                {
                        IEnumerator rootIter = node.GetEnumerator();
                        while( rootIter.MoveNext() )
                        {
                                  XmlNode currentNode = (XmlNode)rootIter.Current;
                                  data = currentNode[TheChild ].InnerText;
                                  break;
                        }
 
                        return data;
                }
}

---

Aright so I changed my code to match yours, and tried changing the WriteXML() to sorta match the LoadXML() method. Came out to:

public static string LoadXML(String TheParent, String TheChild)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.Load(@"SP.xml");

System.Xml.XmlNode node = doc.DocumentElement;
string data = "";
{
if (node.LocalName == "XMLDoc")
{
node.SelectSingleNode(TheParent);
System.Collections.IEnumerator rootIter = node.GetEnumerator();
while (rootIter.MoveNext())
{
System.Xml.XmlNode currentNode = (System.Xml.XmlNode)rootIter.Current;
data = currentNode[TheChild].InnerText;
break;
}

//return data;
}
}
return data;
}


public void WriteXML(String TheParent, String TheChild, String TheValue)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.Load(@"SP.xml");

System.Xml.XmlNode node = doc.DocumentElement;
node.SelectSingleNode(TheParent);
System.Collections.IEnumerator rootIter = node.GetEnumerator();
while (rootIter.MoveNext())
{
System.Xml.XmlNode currentNode = (System.Xml.XmlNode)rootIter.Current;
currentNode[TheChild].SetAttribute(TheChild, TheValue);
break;
}






private void button1_Click(object sender, EventArgs e)
{
int TestMe = 15;// Int32.Parse(LoadXML("Main", "Subjects")) + 1;
WriteXML("Main", "Subjects", TestMe.ToString());
QsStr.Text = LoadXML("Main", "Subjects");
}


...Same thing. The LoadXML() works fine, and i'm even checking the .xml itself, and it isn't changing. Theres no error but it won't write the file. I also checked the debug folder and there is no extra file in there that it may have written to. =( Any ideas or suggestions?

Kk I updated it and came out to this:

public static string LoadXML(String TheParent, String TheChild)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.Load(@"SP.xml");

System.Xml.XmlNode node = doc.DocumentElement;
string data = "";
{
if (node.LocalName == "XMLDoc")
{
node.SelectSingleNode(TheParent);
System.Collections.IEnumerator rootIter = node.GetEnumerator();
while (rootIter.MoveNext())
{
System.Xml.XmlNode currentNode = (System.Xml.XmlNode)rootIter.Current;
data = currentNode[TheChild].InnerText;
break;
}

}
}
return data;
}


public void WriteXML(String TheParent, String TheChild, String TheValue)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.Load(@"SP.xml");

System.Xml.XmlNode node = doc.DocumentElement;
node.SelectSingleNode(TheParent);node.SelectSingleNode(TheChild);
System.Xml.XmlTextWriter Writer = new System.Xml.XmlTextWriter("SP.xml", System.Text.UTF8Encoding.UTF8);
Writer.WriteString(TheValue);
node.WriteTo(Writer);
doc.Save(@"SP.xml");
}





private void button1_Click(object sender, EventArgs e)
{
WriteXML("Main", "Subjects", "W00000000000T OMG IT WORKS!!!!!!!!!!!!!!!!");
}







And there are no build errors at first. I open it up after I build the prog, and it looks like:

W00000000000T OMG IT WORKS!!!!!!!!!!!!!!!!<XMLDoc><Main><Subjects>3</Subjects></Main></XMLDoc>


when it used to look like:

<XMLDoc>
<Main>
<Subjects>3</Subjects>
</Main>
</XMLDoc>


Then I build it again and there is an error message:

doc.Load(@"SP.xml");


Data at the root level is invalid. Line 1, position 1.








Not sure what this means.. Any ideas? I know LoadXML() works, but I can't figure out how to write my message inside the <Subjects> node. Thx.

sorry i forgot to write, the writing code

Code:

---

private void SetElement(XmlElement settingElement, string path, string value)
{
    if( settingElement[path].InnerText == value)
    {
          settingElement[path].InnerText = value;
    }
    else
    {
                XmlDocument doc = settingElement.OwnerDocument;
                XmlElement newElement = doc.CreateElement(path)
                newElement[path].InnerText = value
      }
   
}

---

Code:

---

private void WriteXml(string parent, string child, string value)
{
    XmlDocument doc = new XmlDocument();
    doc.Load(filename);

    XmlNode node = doc.DocumentElement;

IEnumerator rootIter = node.GetEnumerator();
    while( rootIter .MoveNext() )
    {
        XmlNode curnode = (XmlNode)rootIter .Current;
        if( curnode.LocalName == child )
        {
            SetElement(curnode, child, value);
            break;
        }
    }

    doc.Save(filename)

}

---

basically this is how i usually do it. Basically you need also to add some checking in the setting area if ever there is an exception.


// i have not compiled the code above, so there might be some syntax error
// hope it works..

Hey, so I played around with it - still having problems. This is what I have:

public void WriteXML(String TheParent, String TheChild, String TheValue)
{
System.Xml.XmlDocument doc = new System.Xml.XmlDocument();
doc.Load(@"SP.xml");

System.Xml.XmlNode node = doc.DocumentElement;

System.Collections.IEnumerator rootIter = node.GetEnumerator();
while( rootIter .MoveNext() )
{
System.Xml.XmlElement curNode = (System.Xml.XmlElement)rootIter.Current;
if (curNode.LocalName == TheChild)
{
SetElement(curNode, TheChild, TheValue);
break;
}
}

doc.Save(@"SP.xml");
}




private void SetElement(System.Xml.XmlElement settingElement, string path, string value)
{
if( settingElement[path].InnerText == value)
{
settingElement[path].InnerText = value;
}
else
{
System.Xml.XmlDocument doc = settingElement.OwnerDocument;
System.Xml.XmlElement newElement = doc.CreateElement(path);
newElement[path].InnerText = value;
}

}





WriteXML("Main", "Subjects", "W00000000000T OMG IT WORKS!!!!!!!!!!!!!!!!");




SP.xml
<XMLDoc>
<Main>
<Subjects>3</Subjects>
<Questions>18</Questions>
<Answered>12</Answered>
<Correct>9</Correct>
</Main>
</XMLDoc>






When I try to build it I get an error on:

if( settingElement[path].InnerText == value) Object reference not set to an instance of an object. Any ideas or suggestions?

I got it to work now =)

Check: http://www.dotnetforums.net/showthre...300#post458300