[2005] Best practices when saving my application's project data.

[maikeru-sama]

I am currently writing an application that accepts N number of files that will be processed. For each file, the user will be able to manipulate about 30 different pieces of information. Of course, I am allowing the user to save these files as one project, so they can re-load it for later use.

Right now, I am saving this information as a "txt" file. Here is what I am doing:

1) Line 1, I write "Project=MyProject". This is what I am using as one of the way to verify that the "txt" file is a genuine project made in my application.

2) For each subsequent line, I write out each individual file and its 30 pieces of information separated by the "|" symbol.

I want to make sure I am doing this the way most here would do it. Is there a better more efficient way to save project data, or is what I am doing fall in line with what people here would do?

[gnaver]

you could also create a class, make it Serializable, create a new object of this, with all the imformation an save it as i file ... that a pretty easy way of doing it..

or maybe save it as xml.

[maikeru-sama]

you could also create a class, make it Serializable, create a new object of this, with all the imformation an save it as i file ... that a pretty easy way of doing it..

or maybe save it as xml.

Hmmm, never thought about using xml before. The app is almost finished but I may have to look into that.

As far as a class, I thought extremely hard about that but I was a little worried about passing all those objects around in memory, but that may have been inconsequential as I will admit I am not sure about that aspect.

Right now the data is being saved in a Datatable, which may or may not have been the same as objects.

[maikeru-sama]

I will do some research on my own, but would I make the XML file by writing the elements out to a file or is there a .Net class that would help me make the XML structure?

[gnaver]

maybe you can use the xmltextWriter class, (Xml.XmlTextWriter)

[maikeru-sama]

Quick question, I found this example:
http://www.java2s.com/Code/VB/XML/Bu...MLDocument.htm

Unfortunately, it doesn't show how to write it out to a file. Based off of the example above is this the best method to write the data to a file:

'ms = MemoryStream Object

                'make file
                fr = New StreamReader(ms)
                ms.Seek(0, SeekOrigin.Begin)
                fw = New StreamWriter(FileName, False)
                fw.Write(fr.ReadToEnd())
                fw.Close()
                fr.Close()

I don't really like opening up a Stream-reader/writer, so I am wondering if there is a way to just use the streamwriter.

[gnaver]

Dim xml_text_writer As New Xml.XmlTextWriter("c:\yourfile.xml", System.Text.Encoding.ASCII)

[maikeru-sama]

gnaver, thanks I will try that out.

I have one other question for you. It is a basic XML question regarding empty values.

1) When I have value for a an element, it writes:
<Element> </Element>

2) When I have an empty value, it writes:
<Element />

When I trying to retrieve this element back, will this prevent me from getting the data if it is in form #2? If so, is there a way to write it out like #1 everytime?

[gnaver]

you cant retrieve that element as it is empty :S...

but you can stil read the xml file whit no problems..

[techgnome]

the second option there is the prefered way to write out an empty xml element.

Ok, here's how I'd do it: Create a class that contains all of the properties that you need to keep track of per project. Don't worry about passing around "all those objects" ... an object never gets passed, only a pointer (an address if you like) gets passed, and that's a lot smaller than say an array or a dozen string variables.

Next, I'd make the class serializable. That's as simple as adding the serializable namespace to the class, then decorating the class with the <serializable> tag.

Next thing to do would be to write a ReadProject and a WriteProject routine. At this point you have two choices - to write the data out in an XML file or write it out in binary format. Binary has the advantage of potentially being smaller, also since it write binary out, the file isn't easily readable except by your application. XML on the other had will be slightly larger (it is verbose after all) but it can also be modified in something as simple as notepad.

What you'll want to do at this point is to read up on XMLSerialization and BinarySerialization and decide which you want, then write the code (about 3-5 lines to write it to file, and 3-5 to read it back in). By using this method you don't have to parse anything, just write the file and read the file.

In either case, you can also give the files a new extension that you can then associate with your application, so that if a user double clicks it in file explorer, it opens your app then loads the file.

-tg

[gnaver]

to save a class to binary:

Private sub SaveYourClass(ByVal obj2Save As YourClass, ByVal fileName As String) As Boolean
 
        Try
            Dim bf As New Runtime.Serialization.Formatters.Binary.BinaryFormatter()
            Dim mem As New IO.MemoryStream
            bf.Serialize(mem, obj2Save)
            My.Computer.FileSystem.WriteAllText(fileName, Convert.ToBase64String(mem.ToArray()), False)
 
        Catch ex As ApplicationException
            MessageBox.Show(ex.Message)
        End Try
 
    End Sub

To load the binary again:

Private Function LoadClass(ByVal fileName As String) As YourClass
        Try
            Dim File As String = My.Computer.FileSystem.ReadAllText(fileName)
 
            Dim bf As New Runtime.Serialization.Formatters.Binary.BinaryFormatter()
            Dim mem As New IO.MemoryStream(Convert.FromBase64String(File))
            Return (DirectCast(bf.Deserialize(mem), YourClass))
 
        Catch ex As ApplicationException
            MessageBox.Show(ex.Message)
            Return Nothing
        End Try
 
    End Function

[maikeru-sama]

Question, as I told you all before, I have a datatable and each row has the information for the file, could I write that Datatable as binary?

Also, I have always been curious about file extensions. Do you have to make sure there isn't an extension that already exists? For example, if I wanted to use ".mdg", do I check and see if that is registered with a software app?

[gnaver]

you can save your datatable as binary ... use whatever you like, maybe dont use exe,bat etc.

[maikeru-sama]

It's official, you all are geniuses. I used the save/load binary functions with slight modifications and it worked like a charm.

I was extremely uneasy about doing it the way I described in the OP, so thank you all for helping me do things in a more efficient manner.