Develop Reference

How to resolve IOException "file used by another process" while saving XmlDocument?

When I'm trying to save the XML Document I edited the IOException "file used by another process" occured when I try to save that document.
Any ideas how to solve this?
Note: This method is called everytime a new element in the XmlDocument should be written.
public void saveRectangleAsXMLFragment()
{
XmlDocument doc = new XmlDocument();
doc.Load("test.xml");
XmlDocumentFragment xmlDocFrag = doc.CreateDocumentFragment();
String input = generateXMLInput();
xmlDocFrag.InnerXml = input;
XmlElement mapElement = doc.DocumentElement;
mapElement.AppendChild(xmlDocFrag);
input = null;
mapElement = null;
xmlDocFrag = null;
doc.Save("test.xml");
}

Its probably one of your other methods, or other part of the code which opened the file and didnt calose it well. Try to search for this kind of problem.

try this if your's application is only access that .xml file
1. Create a Object globally
object lockData = new object();
2.Use than object to lock statement where you save and load xml
lock(lockData )
{
doc.Load("test.xml");
}
lock(lockData )
{
doc.Save("test.xml");
}

From Jon Skeet's related answer (see https://stackoverflow.com/a/8354736/4151626)
There seems to be a bug in XmlDocument.Save()'s treatment of the file stream, where it becomes pinned and is neither Closed() nor Disposed(). By taking direct control of the creation and disposition of the stream outside of the XmlDocument.Save() I was able to get around this halting error.
//e.g.
XmlWriter xw = new XmlWriter.Create("test.xml");
doc.Save(xw);
xw.Close();
xw.Dispose();

Unable to save changes to XML document stored in Sharepoint 2010 Document Library

I am working on a project that requires all SQL connection and query information to be stored in XML files. To make my project configurable, I am trying to create a means to let the user configure his sql connection string information (datasource, catalog, username and password) via a series of text boxes. This input will then be saved to the appropriate node within the SQL document.
I can get the current information from the XML file, and display that information within text boxes for the user's review and correction, but I'm encountering an error when it comes time to save the changes.
Here is the code I'm using to update and save the xml document.
protected void submitBtn_Click(object sender, EventArgs e)
{
SPFile file = methods.web.GetFile("MyXMLFile.xml");
myDoc = new XmlDocument();
byte[] bites = file.OpenBinary();
Stream strm1 = new MemoryStream(bites);
myDoc.Load(strm1);
XmlNode node;
node = myDoc.DocumentElement;
foreach (XmlNode node1 in node.ChildNodes)
{
foreach (XmlNode node2 in node1.ChildNodes)
{
if (node2.Name == "name1")
{
if (node2.InnerText != box1.Text)
{
}
}
if (node2.Name == "name2")
{
if (node2.InnerText != box2.Text)
{
}
}
if (node2.Name == "name3")
{
if (node2.InnerText != box3.Text)
{
node2.InnerText = box3.Text;
}
}
if (node2.Name == "name4")
{
if (node2.InnerText != box4.Text)
{
}
}
}
}
myDoc.Save(strm1);
}
Most of the conditionals are empty at this point because I'm still testing.
The code works great until the last line, as I said. At that point, I get the error "Memory Stream is not expandable." I understand that using a memory stream to update a stored file is incorrect, but I can't figure out the right way to do this.
I've tried to implement the solution given in the similar question at Memory stream is not expandable but that situation is different from mine and so the implementation makes no sense to me. Any clarification would be greatly appreciated.

Using the MemoryStream constructor that takes a byte array as an argument creates a non-resizable instance of a MemoryStream. Since you are making changes to the file (and therefore the underlying bytes), you need a resizable MemoryStream. This can be accomplished by using the parameterless constructor of the MemoryStream class and writing the byte array into the MemoryStream.
Try this:
SPFile file = methods.web.GetFile("MyXMLFile.xml");
myDoc = new XmlDocument();
byte[] bites = file.OpenBinary();
using(MemoryStream strm1 = new MemoryStream()){
strm1.Write(bites, 0, (int)bites.Length);
strm1.Position = 0;
myDoc.Load(strm1);
// all of your edits to the file here
strm1.Position = 0;
// save the file back to disk
using(var fs = new FileStream("FILEPATH",FileMode.Create,FileAccess.ReadWrite)){
myDoc.Save(fs);
}
}
To get the FILEPATH for a Sharepoint file, it'd be something along these lines (I don't have a Sharepoint development environment set up right now):
SPFile file = methods.web.GetFile("MyXMLFile.xml")
var filepath = file.ParentFolder.ServerRelativeUrl + "\\" + file.Name;
Or it might be easier to just use the SaveBinary method of the SPFile class like this:
// same code from above
// all of your edits to the file here
strm1.Position = 0;
// don't use a FileStream, just SaveBinary
file.SaveBinary(strm1);
I didn't test this code, but I've used it in Sharepoint solutions to modify XML (mainly OpenXML) documents in Sharepoint lists. Read this blogpost for more information

You could look into using the XDocument class instead of XmlDocument class.
http://msdn.microsoft.com/en-us/library/system.xml.linq.xdocument.aspx
I prefer it because of the simplicity and it eliminates having to use Memory Stream.
Edit: You can append to the file like this:
XDocument doc = XDocument.Load('filePath');
doc.Root.Add(
new XElement("An Element Name",
new XAttribute("An Attribute", "Some Value"),
new XElement("Nested Element", "Inner Text"))
);
doc.Save(filePath);
Or you can search for an element and update like this:
doc.Root.Elements("The element").First(m =>
m.Attribute("An Attribute").Value == "Some value to match").SetElementValue(
"The element to change", "Value to set element to");
doc.Save('filePath');

Select xml file part with xpath and xdocument - C#/Win8

I am building a Windows 8 app, and I need to extract the whole XML node and its children as string from a large xml document, and the method that does that so far looks like this:
public string GetNodeContent(string path)
{
XmlReaderSettings settings = new XmlReaderSettings();
settings.IgnoreWhitespace = true;
settings.ConformanceLevel = ConformanceLevel.Auto;
settings.IgnoreComments = true;
using (XmlReader reader = XmlReader.Create("something.xml", settings))
{
reader.MoveToContent();
reader.Read();
XmlDocument doc = new XmlDocument();
doc.LoadXml(reader.ReadOuterXml());
IXmlNode node = doc.SelectSingleNode(path);
return node.InnerText;
}
}
When I pass any form of xpath, node gets the value of null. I'm using the reader to get the first child of root node, and then use XMLDocument to create one from that xml. Since it's Windows 8, apparently, I can't use XPathSelectElements method and this is the only way I can't think of. Is there a way to do it using this, or any other logic?
Thank you in advance for your answers.
[UPDATE]
Let's say XML has this general form:
<nodeone attributes...>
<nodetwo attributes...>
<nodethree attributes... />
<nodethree attributes... />
<nodethree attributes... />
</nodetwo>
</nodeone >
I expect to get as a result nodetwo and all of its children in the form of xml string when i pass "/nodeone/nodetwo" or "//nodetwo"

I've come up with this solution, the whole approach was wrong to start with. The problematic part was the fact that this code
reader.MoveToContent();
reader.Read();
ignores the namespace by itself, because it skips the root tag. This is the new, working code:
public static async Task<string> ReadFileTest(string xpath)
{
StorageFolder folder = await Package.Current.InstalledLocation.GetFolderAsync("NameOfFolderWithXML");
StorageFile xmlFile = await folder.GetFileAsync("filename.xml");
XmlDocument xmldoc = await XmlDocument.LoadFromFileAsync(xmlFile);
var nodes = doc.SelectNodes(xpath);
XmlElement element = (XmlElement)nodes[0];
return element.GetXml();
}

Reading large xml file makes the server stop working - out of memory

I have a piece of code which works well for normal files. But for really big files, it makes the server stop working.
Here it is:
XmlReader reader = null;
try
{
reader = XmlReader.Create(file_name + ".xml");
XDocument xml = XDocument.Load(reader);
XmlNamespaceManager namespaceManager = GetNamespaceManager(reader);
XElement root = xml.Root;
//XAttribute supplier = root.XPathSelectElement("//sh:Receive/sh:Id", namespaceManager).Attribute("Authority");
//string version = root.XPathSelectElement("//sh:DocumentId/sh:Version", namespaceManager).Value;
var nodes = root.XPathSelectElements("//eanucc:msg/eanucc:transact", namespaceManager);
return nodes;
}
catch
{ }
I think this is the part which causes the memory problem which happens on the server. How can I fix this?

It sounds like there's simply too much data to read in one go. You'll have to iterate over the elements one at a time, using XmlReader as a cursor, and converting one element to XElement at a time.
public static IEnumerable<XElement> ReadTransactions()
{
using (var reader = XmlReader.Create(file_name + ".xml"))
{
while (reader.ReadToFollowing("transact", eanuccNamespaceUri))
{
using (var subtree = reader.ReadSubtree())
{
yield return XElement.Load(subtree);
}
}
}
}
Note: this assumes there are never "transact" elements at any other level. If there are, you'll need to be more careful with your XmlReader than just calling ReadToFollowing. Also note that you'll need to find the actual namespace URI of the eanucc alias.
Don't forget that if you try to read all of this information in one go (e.g. by calling ToList()) then you'll still run out of memory. You need to stream the information. (It's not clear what you're trying to do with the elements, but you need to think about it carefully.)

Try putting the reader in a using(){} clause so it gets disposed of after use.
try
{
using(var reader = XmlReader.Create(file_name + ".xml"))
{
XDocument xml = XDocument.Load(reader);
XmlNamespaceManager namespaceManager = GetNamespaceManager(reader);
XElement root = xml.Root;
var nodes = root.XPathSelectElements("//eanucc:msg/eanucc:transact", namespaceManager);
return nodes;
}
}
catch
{ }

Process XML in C# using external entity file

I am processing an XML file (which does not contain any dtd or ent declarations) in C# that contains entities such as é and à. I receive the following exception when attempting to load an XML file...
XmlDocument xmlDoc = new XmlDocument();
xmlDoc.LoadXml(record);
Reference to undeclared entity
'eacute'.
I was able to track down the proper ent file here. How do I tell XmlDocument to use this ent file when loading my XML file?

In versions of the framework prior to .Net 4 you use ProhibitDtd of an XmlReaderSettings instance.
var settings = new XmlReaderSettings();
settings.ProhibitDtd = false;
string DTD = #"<!DOCTYPE doc [
<!ENTITY % iso-lat1 PUBLIC ""ISO 8879:1986//ENTITIES Added Latin 1//EN//XML""
""http://www.oasis-open.org/docbook/xmlcharent/0.3/iso-lat1.ent"">
%iso-lat1;
]> ";
string xml = string.Concat(DTD,"<xml><txt>rené</txt></xml>");
XmlDocument xd = new XmlDocument();
xd.Load(XmlReader.Create(new MemoryStream(
UTF8Encoding.UTF8.GetBytes(xml)), settings));
From .Net 4.0 onward use the DtdProcessing property with a value of DtdProcessing.Parse which you set on the XmlTextReader.
XmlDocument xd = new XmlDocument();
using (var rdr = new XmlTextReader(new StringReader(xml)))
{
rdr.DtdProcessing = DtdProcessing.Parse;
xd.Load(rdr);
}

I ran into the same problem, and not wanting to modify my XML (or DTD), I decided to create my own XmlResolver to add entities on the fly.
My implementation actually reads entities from the config file, but this should be enough to do what you're asking for. In this example, I'm converting a right single curly quote into an apostrophe.
class XmlEntityResolver : XmlResolver {
public override object GetEntity(Uri absoluteUri,
string role,
Type ofObjectToReturn)
{
if (absoluteUri.toString() == "-//MY PUB ID") {
MemoryStream ms = new MemoryStream();
StreamWriter sw = new StreamWriter(ms);
sw.Write("<!ENTITY rsquo \"'\">");
sw.Flush();
ms.Position = 0;
return ms;
}
else {
return base.GetEntity(absoluteUri, role, ofObjectToReturn);
}
}
}
Then, when you declare your XmlDocument, just set the resolver prior to load.
XmlDocument doc = new XmlDocument();
doc.XmlResolver = new XmlEntityResolver();
doc.Load(XML_FILE);

é is not a valid XML entity by default whereas it is a valid HTML entity by default.
You would need to define é as a valid XML entity for XML parsing purposes.
EDIT:
To add a reference to your external ent file you need to do that within the XML file itself. Save the ent file to disk and place it within the same directory as the document being parsed.
<!ENTITY % stuff SYSTEM "iso-lat1.ent">
%stuff;
If you want to go a different route check out the information on ENTITY declaration.

According to this, you have to reference them within the file; you cannot tell LoadXml to do this for you.

Your question has been answered in 2004 itself at MSDN Article........ You can find it here.......
http://msdn.microsoft.com/en-us/library/aa302289.aspx