XMLReader skip current element

[Alex]

For example, i have some part of XML file.

<AppSettings>
<Object ClassVersion="1 .0.0.0" Type="AppSettin gs">
<Fields>
<Field Name="App_ID" Type="System.In t32">
<Value>
<int>-1</int>
</Value>
</Field>
<Field Name="AppDate Type="System.Da teTime">
<Value>
<dateTime>200 7-05-25T00:00:00</dateTime>
</Value>
</Field>
<Field Name="AppFileNa me" Type="System.St ring">
<Value>
<string>TEST 03222007.daf</string>
</Value>
</Field>
<Field Name="AppVersio n" Type="System.St ring">
<Value>
<string>1.0.3.3 </string>
</Value>
</Field>
<Field Name="_ClassVer sion" Type="System.St ring">
<Value>
<string>1.0.0.0 </string>
</Value>
</Field>
</Fields>
</Object>
</AppSettings>

As you can see, its corrupted, because AppDate doesn't gave second ".
I am getting exception when reader.MoveToCo ntent (after i read App_ID)
this all are in try..catch section...
and after that i am receiving smth like string fieldname == "AppDate
Type=";
I can't understand, how i can jump to AppFileName and skip corrupted
AppDate ?
so, how in catch section i can jump to next element ? (during
application's work, i dont know what is the name of next element)

Thanks

[Jon Skeet [C# MVP]]

On Jun 5, 4:29 pm, Alex <[e-mail] gwrote:

<snip>

As you can see, its corrupted, because AppDate doesn't gave second ".

Right. It's an invalid XML file. I would strongly recommend that you
completely reject such files - trying to cope with broken files like
this is a real pain, and I don't know whether XmlReader (or any of the
other .NET XML types) support it.

Jon

[Alex]

<snip>

>

As you can see, its corrupted, because AppDate doesn't gave second ".

Right. It's an invalid XML file. I would strongly recommend that you
completely reject such files - trying to cope with broken files like
this is a real pain, and I don't know whether XmlReader (or any of the
other .NET XML types) support it.

Jon

Sure, i made file to be invalid manually, because i want to add some
improvements to my code, to avoid or solve this problem.

This is just fragment, now file size is 100KB and will be bigger
later.
Also, this file is like XmlSerializatio n of some classes i want to be
serialized.
So, the data which stored are big, and i really don't want user to
fill out all again.

So, if there is some solution about this, i will be glad to here.

[Martin Honnen]

Alex wrote:

For example, i have some part of XML file.

<AppSettings>
<Object ClassVersion="1 .0.0.0" Type="AppSettin gs">
<Fields>
<Field Name="App_ID" Type="System.In t32">
<Value>
<int>-1</int>
</Value>
</Field>
<Field Name="AppDate Type="System.Da teTime">

As you can see, its corrupted, because AppDate doesn't gave second ".
I am getting exception when reader.MoveToCo ntent (after i read App_ID)
this all are in try..catch section...
and after that i am receiving smth like string fieldname == "AppDate
Type=";
I can't understand, how i can jump to AppFileName and skip corrupted
AppDate ?
so, how in catch section i can jump to next element ? (during
application's work, i dont know what is the name of next element)

XML has strict rules, the sample markup is not well-formed and therefore
the XML parser will not parse it but throw an exception. There is no way
to simply skip markup that is not well-formed. So you will not be able
to parse that markup successfully with XmlReader. You have to fix
whatever application generates the markup to produce well-formed XML.
With .NET using XmlWriter can help.
--

Martin Honnen --- MVP XML
http://JavaScript.FAQTs.com/

[Alex]

ok :(

is it possible to read in some another way, but a bit automatically,
and skip problem like that as i need ?
i mean not to use XmlReader, because it can't jump, but use smth else.
But for sure i dont want to write to xmlfile all-all fields manually
(this is just serialization of classes' fields i need).

but, if exception appears - skip field

?

[Peter Duniho]

On Tue, 05 Jun 2007 09:06:51 -0700, Alex <al**@mail.ruwr ote:

is it possible to read in some another way, but a bit automatically,
and skip problem like that as i need ?
i mean not to use XmlReader, because it can't jump, but use smth else.
But for sure i dont want to write to xmlfile all-all fields manually
(this is just serialization of classes' fields i need).

but, if exception appears - skip field

No. The general-purpose XML classes have no practical way to make
intelligent decisions about where to start looking again for valid data.
The only way to do what you want, even in some limited way, is to do
everything yourself.

You as a person can look at the file visually and tell where valid data
again starts, but that's because you have a LOT of "meta-information"
about the XML and can recognize things that would never appear inside
quoted text, but which are definitely part of the XML structure. If you
want your code to handle that, you will need to write it yourself, taking
advantage of this knowledge. If you do this, you will likely want to
implement your entire XML reading code from scratch, so that when you run
across something that doesn't make sense you can recover immediately based
on where you've already read.

Personally, I would not bother. As has been pointed out, the XML is
simply invalid. It's not going to be invalid unless some user hand-edits
the file and starts mucking it up, and once you assume users may do that,
it is impossible to ensure that you can in any sensible way recover from
their doings. You should definitely make sure that bad data doesn't bring
your application crashing down, but it's not reasonable for a user to
expect you to come up with some graceful way to reconstruct the invalid
data in the general case, and so you should probably not waste a lot of
time implementing code that does so.

Pete

[Jon Skeet [C# MVP]]

Alex <al**@mail.ruwr ote:

Right. It's an invalid XML file. I would strongly recommend that you
completely reject such files - trying to cope with broken files like
this is a real pain, and I don't know whether XmlReader (or any of the
other .NET XML types) support it.

Sure, i made file to be invalid manually, because i want to add some
improvements to my code, to avoid or solve this problem.

Is there any real reason why you need to handle an invalid XML file?
Most XML-based applications don't, as far as I'm aware. (Obviously XML
editors have to, but other than that...)

This is just fragment, now file size is 100KB and will be bigger
later.
Also, this file is like XmlSerializatio n of some classes i want to be
serialized.
So, the data which stored are big, and i really don't want user to
fill out all again.

So, if there is some solution about this, i will be glad to here.

Why would the user have to fill anything out again? Why are you
expecting invalid XML?

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

[Peter Duniho]

On Tue, 05 Jun 2007 10:47:27 -0700, Jon Skeet [C# MVP] <sk***@pobox.co m>
wrote:

Is there any real reason why you need to handle an invalid XML file?
Most XML-based applications don't, as far as I'm aware. (Obviously XML
editors have to, but other than that...)

Well, and in fact I'm not sure that XML editors have to either. As an
imprecise but similar example, consider Visual Studio's code editor. If
you miss some sort of closing quote, comment closure, closing bracket,
etc. the editor makes no attempt to recover from that. It just shows you
that there's a problem, treating the file as "valid" all the way up to the
point where it knows for sure it's not valid (which is often the end of
the file).

I can imagine someone writing an XML editor that goes to a lot of effort
to try to detect and correct invalid XML, just as the OP wants to do in
his program. But it would surprise me if this is the norm, even when
looking only at XML editors.

Pete

[Jon Skeet [C# MVP]]

Peter Duniho <Np*********@nn owslpianmk.comw rote:

Is there any real reason why you need to handle an invalid XML file?
Most XML-based applications don't, as far as I'm aware. (Obviously XML
editors have to, but other than that...)

Well, and in fact I'm not sure that XML editors have to either. As an
imprecise but similar example, consider Visual Studio's code editor. If
you miss some sort of closing quote, comment closure, closing bracket,
etc. the editor makes no attempt to recover from that. It just shows you
that there's a problem, treating the file as "valid" all the way up to the
point where it knows for sure it's not valid (which is often the end of
the file).

It depends on quite how broken you make it.

If you miss off a semi-colon or have a random extra character like "+"
between statements, it's still syntactically invalid, but it recovers
quickly. An extra closing brace certainly confuses it though, yes.

I can imagine someone writing an XML editor that goes to a lot of effort
to try to detect and correct invalid XML, just as the OP wants to do in
his program. But it would surprise me if this is the norm, even when
looking only at XML editors.

Maybe it's just the ones I've used - and that's only from memory,
admittedly...

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

[Peter Duniho]

On Tue, 05 Jun 2007 12:47:18 -0700, Jon Skeet [C# MVP] <sk***@pobox.co m>
wrote:

It depends on quite how broken you make it.

If you miss off a semi-colon or have a random extra character like "+"
between statements, it's still syntactically invalid, but it recovers
quickly. An extra closing brace certainly confuses it though, yes.

I suppose "recovers" is in the eye of the beholder. What I see when one
leaves off a semi-colon is that the end of the statement where the
semi-colon was expected is flagged. However, the only reason it can do
that is that it is apparent upon seeing the first thing that doesn't make
sense in that statement (ie, the next statement) where the error is.

But I don't really see that the editor has "recovered" . It is simply
pointing out the first place it has detected a problem. Just as the
compiler won't compile a file even though it could usually correctly infer
the correct location of the semicolon, it's not really like the VS editor
has judged the remainder of the file correct and accurate. In fact, it
gives up on a variety of automatic stuff once it's stumbled (for example,
I've lost count of the number of times that I don't get Intellisense
feedback because of a localized compiler-type error in my source code).

Compilers, code editors, and XML editors alike can all make inferences
about what the input data *should* look like, and try to produce correct
behavior based on those inferences. But my experience (granted, limited
in the case of XML editors, but not so limited in other areas) is that if
the input data does not comply exactly with what's expected, the user is
simply told "this data is bad...I'm not going any further until you fix
it".

Pete