Update a specific XML node

[Alain R.]

Hi,

I have the following XML file :
<?xml version='1.0' encoding='UTF-8'?>
<Database>
<ConnectionString Type="PostgreSQL v8.2.x">
<DBName>c2st</DBName>
<Host>127.0.0.1</Host>
<Port>5432</Port>
<Username>user</Username>
<Password>pwd</Password>
</ConnectionString>
<ConnectionString Type="MySQL v4.x">
<DBName>dbtest</DBName>
<Host>127.0.0.1</Host>
<Port>5432</Port>
<Username>myuser</Username>
<Password>mypwd</Password>
</ConnectionString>
</Database>

How can i update only 1 particular node of this XML file without
browsing the whole nodes ?

for example, i would like to change <PortinnerXML value (5432) to 1258
for MySQL v4.x connection string.

All methods i've read till now are browsing the whole nodes and this i
would like to avoid as much as possible.

thanks a lot,

Alain

[Jon Skeet [C# MVP]]

On Aug 13, 7:50 am, "Alain R." <[e-mail]:

<snip>

How can i update only 1 particular node of this XML file without
browsing the whole nodes ?

for example, i would like to change <PortinnerXML value (5432) to 1258
for MySQL v4.x connection string.

All methods i've read till now are browsing the whole nodes and this i
would like to avoid as much as possible.

What exactly do you mean by "browsing the whole nodes"? The easiest
way is probably to use an XPath expression to find the element you
want, and then update it. However, I don't know whether that would
count as "browsing the whole nodes" in your view.

If you want to update the file, you'll have to rewrite the whole thing
though.

Jon

[Jon Skeet [C# MVP]]

On Aug 13, 10:07 am, "Alain R." <[e-mail]:

I did that (see below) and it works well...i'm just scared when XMl file
will be huge.

So how big do you expect your files to be, and have you tested it with
a file that large?

It's better to have evidence under your belt than to be scared of
something that may not be a problem.

Jon

[Alain R.]

for now XML is les than 1 kb as i just started to work on it.

but i expect it will reach 600 kb.
Jon Skeet [C# MVP] wrote:

On Aug 13, 10:07 am, "Alain R." <[e-mail]:

>I did that (see below) and it works well...i'm just scared when XMl file
will be huge.

So how big do you expect your files to be, and have you tested it with
a file that large?

It's better to have evidence under your belt than to be scared of
something that may not be a problem.

Jon

[Jon Skeet [C# MVP]]

On Aug 13, 10:35 am, "Alain R." <[e-mail]:

for now XML is les than 1 kb as i just started to work on it.

but i expect it will reach 600 kb.

600K is still relatively small. By the time it's loaded into memory it
will be significantly bigger of course, but unless you're loading and
saving thousands of these on a very frequent basis, I wouldn't expect
it to be a problem.

To be confident, however, you should see if you can create or find a
file of that size, and see how it performs.

Jon

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Alain R. wrote:

for now XML is les than 1 kb as i just started to work on it.

but i expect it will reach 600 kb.

I think DOM in memory size typical is about 5 times on disk size.

In that case it is just 3 MB.

Arne

[Jon Skeet [C# MVP]]

Arne Vajhøj <ar**@vajhoej.dkwrote:

It is not a 100 times.

So have you found the worst cases and measured it?

No - I don't really see any point in it.

If the worst case is known to be okay for the OP's situation, then
there's no need to try a representative file. Otherwise, however, it
*is* a good idea to try one.

You're assuming that *all* of the XML is like the sample posted. 600K
just of database connections is an awful lot - maybe there'll be other
data...

Sure.

But almost by definition I would expect that to be more close
to average than the worst case possible to create.

True - but without knowing how bad the worst case is, that's not much
comfort.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too

[=?ISO-8859-1?Q?Arne_Vajh=F8j?=]

Jon Skeet [C# MVP] wrote:

Arne Vajhøj <ar**@vajhoej.dkwrote:

>>You're assuming that *all* of the XML is like the sample posted. 600K
just of database connections is an awful lot - maybe there'll be other
data...

Sure.

But almost by definition I would expect that to be more close
to average than the worst case possible to create.

True - but without knowing how bad the worst case is, that's not much
comfort.

Why not. If real XML files are <10 it does not matter much if is
possible to construct an example with 17 or 27.

Arne

[Jon Skeet [C# MVP]]

Arne Vajhøj <ar**@vajhoej.dkwrote:

Jon Skeet [C# MVP] wrote:

Arne Vajhøj <ar**@vajhoej.dkwrote:

>You're assuming that *all* of the XML is like the sample posted. 600K
just of database connections is an awful lot - maybe there'll be other
data...
Sure.

But almost by definition I would expect that to be more close
to average than the worst case possible to create.

True - but without knowing how bad the worst case is, that's not much
comfort.

Why not. If real XML files are <10 it does not matter much if is
possible to construct an example with 17 or 27.

But the point is that we didn't know what the genuine XML file would be
like. We hadn't experimented to find out *either* what it would be like
with real data *or* what a worst case would be. Using samples of other
XML files which may or may not be anything like the real one isn't
enough, IMO.

--
Jon Skeet - <sk***@pobox.com>
http://www.pobox.com/~skeet Blog: http://www.msmvps.com/jon.skeet
If replying to the group, please do not mail me too