How to safeguard losing XML file content?

[Nad]

Hello,

I need some help with this:

I am trying to update some data using XmlTextWriter. I instantiate first and
then do some validation and then copy data into the dataset. Finally I commit
the changes. As the following excerpt:

Now the problem is that if there is a validation failure for example,
control ends up in the catch{} block. So xmlWriter is created but nothing is
written into it. At this point it seems that the xml file becomes empty.
Because on the user interface when I exit application (without fixing my
validation error) I end up with an empty xml file. So I lose everything I had
in this file before. One solution I have is to instantiate xmlWriter just
before calling dataSet.WriteXml(xmlWriter) but still in this line an error
could occur and I will lose my data. What is the right solution to such
problem. Thanks a lot for your help.

try
{
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
// validation ...
// writing data into dataset
dataSet.AcceptChanges();
dataSet.WriteXml(xmlWriter);
catch
{
// handle exception ...
}
finally
{
xmlWriter.Close();
}

[James Mahoney]

So you want to load the dataset up (from myfile.xml), modify its contents and
then save the changes back to myfile.xml?

"Nad" wrote:

Hello,

I need some help with this:

I am trying to update some data using XmlTextWriter. I instantiate first and
then do some validation and then copy data into the dataset. Finally I commit
the changes. As the following excerpt:

Now the problem is that if there is a validation failure for example,
control ends up in the catch{} block. So xmlWriter is created but nothing is
written into it. At this point it seems that the xml file becomes empty.
Because on the user interface when I exit application (without fixing my
validation error) I end up with an empty xml file. So I lose everything I had
in this file before. One solution I have is to instantiate xmlWriter just
before calling dataSet.WriteXml(xmlWriter) but still in this line an error
could occur and I will lose my data. What is the right solution to such
problem. Thanks a lot for your help.

try
{
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
// validation ...
// writing data into dataset
dataSet.AcceptChanges();
dataSet.WriteXml(xmlWriter);
catch
{
// handle exception ...
}
finally
{
xmlWriter.Close();
}

[Nad]

Yes, and I wonder how I can prevent losing the whole content of the xml file
if something goes wrong when WriteXml fails. Because if it does in the
following code snippet I will lose the content. All I'm doing now is backing
up the file before I load it up, so at least I won't lose much.

// validation ...
// writing data into dataset
dataSet.AcceptChanges();
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
dataSet.WriteXml(xmlWriter);
"James Mahoney" wrote:

So you want to load the dataset up (from myfile.xml), modify its contents and
then save the changes back to myfile.xml?

"Nad" wrote:

Hello,

I need some help with this:

I am trying to update some data using XmlTextWriter. I instantiate first and
then do some validation and then copy data into the dataset. Finally I commit
the changes. As the following excerpt:

Now the problem is that if there is a validation failure for example,
control ends up in the catch{} block. So xmlWriter is created but nothing is
written into it. At this point it seems that the xml file becomes empty.
Because on the user interface when I exit application (without fixing my
validation error) I end up with an empty xml file. So I lose everything I had
in this file before. One solution I have is to instantiate xmlWriter just
before calling dataSet.WriteXml(xmlWriter) but still in this line an error
could occur and I will lose my data. What is the right solution to such
problem. Thanks a lot for your help.

try
{
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
// validation ...
// writing data into dataset
dataSet.AcceptChanges();
dataSet.WriteXml(xmlWriter);
catch
{
// handle exception ...
}
finally
{
xmlWriter.Close();
}

[Chris Lovett]

Write to a different file, then only if it was successful, delete the old
file and rename the new.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:70**********************************@microsof t.com...

Yes, and I wonder how I can prevent losing the whole content of the xml
file
if something goes wrong when WriteXml fails. Because if it does in the
following code snippet I will lose the content. All I'm doing now is
backing
up the file before I load it up, so at least I won't lose much.

// validation ...
// writing data into dataset
dataSet.AcceptChanges();
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
dataSet.WriteXml(xmlWriter);
"James Mahoney" wrote:

So you want to load the dataset up (from myfile.xml), modify its contents
and
then save the changes back to myfile.xml?

"Nad" wrote:

> Hello,
>
> I need some help with this:
>
> I am trying to update some data using XmlTextWriter. I instantiate
> first and
> then do some validation and then copy data into the dataset. Finally I
> commit
> the changes. As the following excerpt:
>
> Now the problem is that if there is a validation failure for example,
> control ends up in the catch{} block. So xmlWriter is created but
> nothing is
> written into it. At this point it seems that the xml file becomes
> empty.
> Because on the user interface when I exit application (without fixing
> my
> validation error) I end up with an empty xml file. So I lose everything
> I had
> in this file before. One solution I have is to instantiate xmlWriter
> just
> before calling dataSet.WriteXml(xmlWriter) but still in this line an
> error
> could occur and I will lose my data. What is the right solution to such
> problem. Thanks a lot for your help.
>
> try
> {
> XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
> Encoding.UTF8);
> // validation ...
> // writing data into dataset
> dataSet.AcceptChanges();
> dataSet.WriteXml(xmlWriter);
> catch
> {
> // handle exception ...
> }
> finally
> {
> xmlWriter.Close();
> }

[Nad]

Thanks for the solution. I don't like xml you know, it's never as safe as
databases.

"Chris Lovett" wrote:

Write to a different file, then only if it was successful, delete the old
file and rename the new.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:70**********************************@microsof t.com...

Yes, and I wonder how I can prevent losing the whole content of the xml
file
if something goes wrong when WriteXml fails. Because if it does in the
following code snippet I will lose the content. All I'm doing now is
backing
up the file before I load it up, so at least I won't lose much.

// validation ...
// writing data into dataset
dataSet.AcceptChanges();
XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml", Encoding.UTF8);
dataSet.WriteXml(xmlWriter);
"James Mahoney" wrote:

So you want to load the dataset up (from myfile.xml), modify its contents
and
then save the changes back to myfile.xml?

"Nad" wrote:

> Hello,
>
> I need some help with this:
>
> I am trying to update some data using XmlTextWriter. I instantiate
> first and
> then do some validation and then copy data into the dataset. Finally I
> commit
> the changes. As the following excerpt:
>
> Now the problem is that if there is a validation failure for example,
> control ends up in the catch{} block. So xmlWriter is created but
> nothing is
> written into it. At this point it seems that the xml file becomes
> empty.
> Because on the user interface when I exit application (without fixing
> my
> validation error) I end up with an empty xml file. So I lose everything
> I had
> in this file before. One solution I have is to instantiate xmlWriter
> just
> before calling dataSet.WriteXml(xmlWriter) but still in this line an
> error
> could occur and I will lose my data. What is the right solution to such
> problem. Thanks a lot for your help.
>
> try
> {
> XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
> Encoding.UTF8);
> // validation ...
> // writing data into dataset
> dataSet.AcceptChanges();
> dataSet.WriteXml(xmlWriter);
> catch
> {
> // handle exception ...
> }
> finally
> {
> xmlWriter.Close();
> }

[Chris Lovett]

XML is mostly for data-exchange, not storage. So yes, if the file system
isn't cutting it, switch to SQL Server. The new SQL Express you can
download from MSDN supports XML DataType with XQuery support over columns of
that type, so you get the best of both worlds.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:7D**********************************@microsof t.com...

Thanks for the solution. I don't like xml you know, it's never as safe as
databases.

"Chris Lovett" wrote:

Write to a different file, then only if it was successful, delete the old
file and rename the new.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:70**********************************@microsof t.com...

> Yes, and I wonder how I can prevent losing the whole content of the xml
> file
> if something goes wrong when WriteXml fails. Because if it does in the
> following code snippet I will lose the content. All I'm doing now is
> backing
> up the file before I load it up, so at least I won't lose much.
>
> // validation ...
> // writing data into dataset
> dataSet.AcceptChanges();
> XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
> Encoding.UTF8);
> dataSet.WriteXml(xmlWriter);
>
>
> "James Mahoney" wrote:
>
>> So you want to load the dataset up (from myfile.xml), modify its
>> contents
>> and
>> then save the changes back to myfile.xml?
>>
>> "Nad" wrote:
>>
>> > Hello,
>> >
>> > I need some help with this:
>> >
>> > I am trying to update some data using XmlTextWriter. I instantiate
>> > first and
>> > then do some validation and then copy data into the dataset. Finally
>> > I
>> > commit
>> > the changes. As the following excerpt:
>> >
>> > Now the problem is that if there is a validation failure for
>> > example,
>> > control ends up in the catch{} block. So xmlWriter is created but
>> > nothing is
>> > written into it. At this point it seems that the xml file becomes
>> > empty.
>> > Because on the user interface when I exit application (without
>> > fixing
>> > my
>> > validation error) I end up with an empty xml file. So I lose
>> > everything
>> > I had
>> > in this file before. One solution I have is to instantiate xmlWriter
>> > just
>> > before calling dataSet.WriteXml(xmlWriter) but still in this line an
>> > error
>> > could occur and I will lose my data. What is the right solution to
>> > such
>> > problem. Thanks a lot for your help.
>> >
>> > try
>> > {
>> > XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
>> > Encoding.UTF8);
>> > // validation ...
>> > // writing data into dataset
>> > dataSet.AcceptChanges();
>> > dataSet.WriteXml(xmlWriter);
>> > catch
>> > {
>> > // handle exception ...
>> > }
>> > finally
>> > {
>> > xmlWriter.Close();
>> > }

[Nad]

Well I am using xml as storage, but a small and simple one.

Thanks fa lot or the SQL Express hint, I'll give it a try.

"Chris Lovett" wrote:

XML is mostly for data-exchange, not storage. So yes, if the file system
isn't cutting it, switch to SQL Server. The new SQL Express you can
download from MSDN supports XML DataType with XQuery support over columns of
that type, so you get the best of both worlds.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:7D**********************************@microsof t.com...

Thanks for the solution. I don't like xml you know, it's never as safe as
databases.

"Chris Lovett" wrote:

Write to a different file, then only if it was successful, delete the old
file and rename the new.

"Nad" <Na*@discussions.microsoft.com> wrote in message
news:70**********************************@microsof t.com...
> Yes, and I wonder how I can prevent losing the whole content of the xml
> file
> if something goes wrong when WriteXml fails. Because if it does in the
> following code snippet I will lose the content. All I'm doing now is
> backing
> up the file before I load it up, so at least I won't lose much.
>
> // validation ...
> // writing data into dataset
> dataSet.AcceptChanges();
> XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
> Encoding.UTF8);
> dataSet.WriteXml(xmlWriter);
>
>
> "James Mahoney" wrote:
>
>> So you want to load the dataset up (from myfile.xml), modify its
>> contents
>> and
>> then save the changes back to myfile.xml?
>>
>> "Nad" wrote:
>>
>> > Hello,
>> >
>> > I need some help with this:
>> >
>> > I am trying to update some data using XmlTextWriter. I instantiate
>> > first and
>> > then do some validation and then copy data into the dataset. Finally
>> > I
>> > commit
>> > the changes. As the following excerpt:
>> >
>> > Now the problem is that if there is a validation failure for
>> > example,
>> > control ends up in the catch{} block. So xmlWriter is created but
>> > nothing is
>> > written into it. At this point it seems that the xml file becomes
>> > empty.
>> > Because on the user interface when I exit application (without
>> > fixing
>> > my
>> > validation error) I end up with an empty xml file. So I lose
>> > everything
>> > I had
>> > in this file before. One solution I have is to instantiate xmlWriter
>> > just
>> > before calling dataSet.WriteXml(xmlWriter) but still in this line an
>> > error
>> > could occur and I will lose my data. What is the right solution to
>> > such
>> > problem. Thanks a lot for your help.
>> >
>> > try
>> > {
>> > XmlTextWriter xmlWriter = new XmlTextWriter("myFile.xml",
>> > Encoding.UTF8);
>> > // validation ...
>> > // writing data into dataset
>> > dataSet.AcceptChanges();
>> > dataSet.WriteXml(xmlWriter);
>> > catch
>> > {
>> > // handle exception ...
>> > }
>> > finally
>> > {
>> > xmlWriter.Close();
>> > }