[普通]a question about XmlTextReader.ReadBase64()

clip · #1 (**permalink**) 2004-08-26

Hi, I am new to xml, so if I ask something stupid or funny, pls don't laugh.
my problem is like this:
I have a data structure like this

代码:

class mydata
{
	byte[] data;
};
// I wrote it to xml like this
	XmlTextureWriter writer;
	writer.WriteStartElement("MyData");
	writer.WriteAttributeString("Length",md.data.Length.ToString());
	writer.WriteBase64(md.data,0,md.data.Length);
	writer.WriteEndElement();

// I want to read it out 
XmlTextReader reader;
while(reader.Read())
{
	switch(reader.NodeType)
	{
		case XmlNodeType.Element:
			MyData md = new MyData();
			while(reader.MoveToNextAttribute())
			{
				if(reader.Value == "Length")
				md.data = new byte[Int32.Parse(reader.Value)];
			}
			reader.MoveToContent();
			reader.ReaderBase64(md.data,0,md.data.Length);
		break;
		case XmlNodeType.EndElement:
			
		break;
	
	}
}

Anyone has any suggestion?
Thanks a lot!

PingDong · #2 (**permalink**) 2004-08-26

Sorry, I don't know what you want.Save some data in XML file, then read it?

You need a schema or DTD to define data structure first. It will like attachment. Sometime, data and schema save in same file, some time not.

XML data structure it isn't like the way you define class. It isn't define separately with the application.

clip · #3 (**permalink**) 2004-08-27

Sorry for the confusion.
What I wanted to do is save a data structure (i used to do that by save it as a binary file), this time I try to save it as xml. Since I am not familizr with xml at all, so possibly I have choose a stupid way doing this. I attach a simplified project to show how I do that. If there is more sophisticated or simpler way you can show me, it's very appreciated.

Please ignore my previous question, it's due to my understading of "EndElement".

PingDong · #4 (**permalink**) 2004-08-27

This sunday, I'm going to write a sample.

The easy way to handle XML is treat it as DataSet. You can simple import XML to DataSet. Then you use it like retrieve from Database.

clip · #5 (**permalink**) 2004-08-28

great! what I most care is write a data struture into xml and the read from it. if you can give an example of standard way doing it. that will be great. thx!

PingDong · #6 (**permalink**) 2004-08-28

Here is a very simple demo source. When you click button - loadXML, it will load XML file's contents into a dataset. Then display it. After that you click button - SaveXML, it gonna save a new xml file named new_customer.xml. It very simple. But it show a quick way and mostly used way to handle XML contents.

After loaded Customers, it will append their name in TextBox, I use some XML concept to do that, XPath to get all names.

The XML source is also simple, I didn't write a schema for it. In real world, most XML come with a DTD or schema to tell you the XML content's structure.

The way you used, WriteStartElement.., it is like we create a HTTP stream from coding. But you know, we never create a website by that way. Mostly we create HTML sepearately and with some professional tools, and use some app to read it or save it. To XML, we do the same thing.

PingDong · #7 (**permalink**) 2004-08-28

MS hide tech behind that. Read XML as its structure(we common call it schema) it did by XML parser.

I think, for user, XPath is a great and interested thing. XPath is the way to find what you want in XML file.

clip · #8 (**permalink**) 2004-08-29

thx.
I can read and write xml from/to data structure now,see the attached code. The problem is anytime I change the data structure, I had to remember change both place. hope there is a better way.

PingDong · #9 (**permalink**) 2004-08-29

I guess, you use C++ a long time and a smart guy. You are glad to do everything by your own code.

I just brief your code. I think you want to save instances of a Class in the XML file. Am I right? If yes, why don't you use XML serialize?

Check XmlSerializer Class in MSDN.

clip · #10 (**permalink**) 2004-08-29

thanks a lot.
this is exactly what I am looking for.

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