Reading and Writing to XML file

[shalan99]

Hi everyone,

I've been doin some reading on using the XML Designer in VS.NET to create an XSD schema, create an XML document based on that schema, and generate a dataset from that schema.

I now want to know how to read/write/update/delete data to/from that XML file using VB in WinForms.

Please could someone point me in the direction of a good and thorough tutorial?

I googled for it, but I'm still drawing a blank!

Much thanx
Shalan99

 

[cjard]

I dont quite understand.. But if you use the dataset designer to make an XML file representing your dataset, you can save and load it with teh ReadXml and WriteXml methods

 

[shalan99]

Hi again cjard & thanx 4 the response!
(in advance Please forgive me 4 any elementary comments that I may make!!)

A friend shared some video tutorials with me on How to use the XML Designer in VS.NET, from which I've managed 2 create a schema, create an XML file for the data to be stored in, and create a dataset based on that schema.

I am used to using SQL Server DBs to store data, but instead want to use an XML file. I am quite new to data access in .NET so I am still learning as I go along. I want 2 create and distribute a Windows application, so I don't know if using a SQL Express db would be feasible. Cjard, is there a major difference with regards to performance if I use an XML file instead of a relational db like SQL Express?

Also, with regards to your last point, would I not read/write to the dataset which will automatically read/write to the XML file?

 

[cjard]

Hi again cjard & thanx 4 the response!
(in advance Please forgive me 4 any elementary comments that I may make!!)

A friend shared some video tutorials with me on How to use the XML Designer in VS.NET, from which I've managed 2 create a schema, create an XML file for the data to be stored in, and create a dataset based on that schema.

I am used to using SQL Server DBs to store data, but instead want to use an XML file. I am quite new to data access in .NET so I am still learning as I go along. I want 2 create and distribute a Windows application, so I don't know if using a SQL Express db would be feasible. Cjard, is there a major difference with regards to performance if I use an XML file instead of a relational db like SQL Express?

Also, with regards to your last point, would I not read/write to the dataset which will automatically read/write to the XML file?

Err.. I dont really recall seeing anything that uses an XML file like a database. ReadXml and WriteXml are ways of saving a dataset to disk. THey are in NO WAY a replacement for a relational database management system. If you need to store data, use a database. If its only a small amount of read only data, then sure, use a dataset that you read and write out of an xml file

Dont try to use a dataset as a database for complex or large things; even an access database would be preferable to that..

 

[shalan99]

oops! now im quite embarrassed! sorry about that. but its ok...its a learning curve for me.

Agreed about the relational database bit tho. I think I need to do a lot more reading on this subject, and more 2 understand datasets and how 2 use them with databases or XML files. I know that a dataset is a local representation of database objects. With that in mind, would I be interacting with a Data Source (DB or XML) in a disconnected fashion thru the dataset?

I do intend to store 2 small sets of data...typically i would have done so in 2 different tables, with one foreign key relation between them. Can i still use an XML file for this?

regards

 

[cjard]

With that in mind, would I be interacting with a Data Source (DB or XML) in a disconnected fashion thru the dataset?

Correct

I do intend to store 2 small sets of data...typically i would have done so in 2 different tables, with one foreign key relation between them. Can i still use an XML file for this?

regards

You can. For example I have a small app that needs to store a moderate amount of data. It is too much for the Settings, and not enough to warrant a DB, so i store it all in a dataset, and just read and write that dsataset xml from and to disk at app startup and shutdown respectively..

I dont think youll find random access of XML files works speedily.. ie using them like a database is a nono.. But they can be used well to store a dataset in between program runs. Ask over in the XML forum.. JohnH will know.

 

[shalan99]

not enough to warrant a DB, so i store it all in a dataset, and just read and write that dsataset xml from and to disk at app startup and shutdown respectively..

My scenario sounds very similar. Ok, so my understanding is as follows:

• datasets work with data sources in a sort of localised, disconnected way
• doing this helps with db security & also improves performance by not having to connect to the datasource all the time (esp if I had to read data in a timer tick event every 5 minutes for example)
• I can work with the data itself via the dataset

In that regard I guess where I am lacking in knowledge is how to use the Dataset syntax itself in my code-behind for writing/writing back to/from the dataset or iterating thru "rows" in the dataset to look for a specific values in a "column". I think that is where I need to find a walkthru or tutorial on.

Thank u for all your help tho cjard, u have been very patient with me! I will enquire more from JohnH on XML matters and also look into the ADO.NET forum section.

Cheers!
shalan99

 

[shalan99]

sorry...typo...ment to say "writing/reading to/from the dataset"