Improve company productivity with a Business Account.Sign Up

x
  • Status: Solved
  • Priority: Medium
  • Security: Public
  • Views: 978
  • Last Modified:

how to append a xml file in c# if exists, or make new if not?

i am adding tracing for audit purposes of a simple process i have built as an .exe and set in the scheduler to run every 10 minutes. i want to have the application output the results into an xml file.

if the file exists then open and append data to it, if it does not exist i want to create a new xml file that will be persisted and used on next run.

here is my code now, what do i need to add, how do i open the xml file (on c:/file.xml) and use it to append nodes to?

also i think my code is like a newbs, so some help in showing me the correct streamlined way would help me learn best practice with C#/ XML

string err = "";
        XmlDocument doc = new XmlDocument();// Create the XML Declaration, and append it to XML document

        XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", null, null);
        doc.AppendChild(dec);// Create the root element

        XmlElement root = doc.CreateElement("STATS");
        doc.AppendChild(root);

        // Create URL's            
        XmlElement urlNode = doc.CreateElement("keepalive");
        urlNode.SetAttribute("runTime", DateTime.Now.ToString());

        try
        {
            WebProxy wp = new WebProxy("http://proxy.ml.com:8083/");
            WebClient w = new WebClient();
            w.Proxy = wp;

            if (w.DownloadString("http://wwww.idealcoding.com") != "")
                urlNode.SetAttribute("result", "UP");
            else
                urlNode.SetAttribute("result", "DOWN");
        }
        catch (Exception ex)
        {
            err = ex.Message;
            urlNode.SetAttribute("result", "DOWN");
        }
        finally {
            root.AppendChild(urlNode);
            doc.Save("c:/keepAlive.xml");
        }

Open in new window



this is my XML file:
 
<STATS>
  <keepalive runTime="11/22/2010 9:40:43 AM" result="UP" /> 
 </STATS>

Open in new window

0
realcoding
Asked:
realcoding
  • 3
  • 2
  • 2
2 Solutions
 
Carl TawnSystems and Integration DeveloperCommented:
What is it you want to add to the file, a new <STATS /> everytime it runs or a new <keepalive /> adding to STATS?
0
 
realcodingAuthor Commented:
i want to just add keepalive nodes, such that each run of the app will log the time it ran and result.
if the file exists i want to load it into the xml object and add a keepalive node with the current runs info and so on... if the xml file does not exist then do as i do here and create a new one.

but as it stands every run of the app creates and over-writes the xml file leaving only one node , not very useful.
0
 
Richard LeeSoftware EnthusiastCommented:
Okay the approach I would take here, and its a slightly different thinking from you is that I would have a Xml Serializable Audit object. I would then read the contents of the file and deserialize into and instance of the Audit class and then add the new entries to this object and overwrite the existing file.

Xml Serializer and Deserializer class:
http://avantprime.com/articles/view-article/13/xml-serialization-and-de-serialization-helper-class-using-generics

Use the StreamReader and StreamWriter classes to manipulate the file on disk.
http://www.c-sharpcorner.com/UploadFile/puranindia/StreamReaderStreamWriterClasses11242009235459PM/StreamReaderStreamWriterClasses.aspx

DaTribe
0
Upgrade your Question Security!

Your question, your audience. Choose who sees your identity—and your question—with question security.

 
Carl TawnSystems and Integration DeveloperCommented:
OK, try replacing these four lines:
        XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", null, null);
        doc.AppendChild(dec);// Create the root element

        XmlElement root = doc.CreateElement("STATS");
        doc.AppendChild(root);

Open in new window

With:
    XmlElement root;

   if (File.Exists(@"c:\keepAlive.xml"))
   {
         doc.Load(@"c:\keepAlive.xml");
         root = doc.SelectSingleNode("/STATS");
   }
   else
   {
        XmlDeclaration dec = doc.CreateXmlDeclaration("1.0", null, null);
        doc.AppendChild(dec);// Create the root element

        root = doc.CreateElement("STATS");
        doc.AppendChild(root);
   }

Open in new window


You may also want to move the filename into a variable to save you typing it over and over again.
0
 
Richard LeeSoftware EnthusiastCommented:
Also to handle when this file gets very large I would write to a new write each hour / day. You could create folders for further organization. File would be suffixed with Date & Time. Folders would be suffixed with Date.

DaTribe
0
 
realcodingAuthor Commented:
why would you use a serializable object? whats the gain?
0
 
Richard LeeSoftware EnthusiastCommented:
The gain for me would be simply manipulating this object easily with c# and then in the end simply turning it back to XML. Avoid the hassles with XML plus another huge bonus would be I could add or remove properties from the Audit class and deserialization would still be successful and as the file contents are over-written when saving then there would be no problem saving the new structure.

I save myself development time and hassles. More maintainable solution. In this instance as its every 10 minutes mission critical performance is not required - still some of the suggestions I provided work around that.

DaTribe
0
Question has a verified solution.

Are you are experiencing a similar issue? Get a personalized answer when you ask a related question.

Have a better answer? Share it in a comment.

Join & Write a Comment

Featured Post

Free Tool: Subnet Calculator

The subnet calculator helps you design networks by taking an IP address and network mask and returning information such as network, broadcast address, and host range.

One of a set of tools we're offering as a way of saying thank you for being a part of the community.

  • 3
  • 2
  • 2
Tackle projects and never again get stuck behind a technical roadblock.
Join Now