[Tutor] Writing to XML file with minidom

[Johan Geldenhuys]

Kent,
Thanks for the tip. I can write the changed data back to my xml file.
One snag that I found is that the des encryption that I used for the
data that is written back, it is not parsed correctly when the file is
read again with the new data in it. There is non-printable characters or
non-ascii chars in that gives errors from expat when the contents is
parsed.
I had to use a different encryption algorithm. I am going to do some
tests on it now.

Johan
 On Tue, 2005-08-30 at 09:47 -0400, Kent Johnson wrote:

> Johan Geldenhuys wrote:
> > That means that I have to compile the whole file from scratch in Python, 
> > minidom.
> > I am not that good, yet, but will try.
> 
> No, not if I understand what you are trying to do - the xmlDocument you have is all the data from the file, just write it back out using the code I posted before.
> 
> > will it be easier to search for the string that I look for in the file 
> > (readlines) and then just write the pieces back again?
> 
> That depends a lot on the data. If you can reliably find what you want by looking at a line at a time, that is a simple approach. But you are almost there with the minidom. Really, just add my three lines of code to what you already have. (Maybe for prudence use a different file name.)
> 
> Kent
> 
> > 
> > Johan
> > On Tue, 2005-08-30 at 07:40 -0400, Kent Johnson wrote:
> > 
> >>Johan Geldenhuys wrote:
> >>> Thanks for he help, so far.
> >>> 
> >>> I am still having some questions on writing my new string back to the 
> >>> xml file after I found what I was looking for and changed it.
> >>> 
> >>> Extracts:
> >>> 
> >>> xmlDocument = minidom.parse(file_name) # open existing file for parsing
> >>> main = xmlDocument.getElementsByTagName('Config')
> >>> main.getElementsByTagName('Connection')
> >>> configSection = mainSection[0]
> >>> 
> >>> for node in configSection: #Here I get the NamedNodeMap info
> >>>         password = node.getAttribute("password")
> >>>         # Do stuff to the password and I have 'newPass'
> >>>        node.removeAttribute('password') # I take out my old attribute 
> >>> and it's value
> >>>        node.setAttribute('password', newPass)
> >>> 
> >>> 
> >>> At this stage I have my new attribute and it's new value, but how do I 
> >>> write that to my file in the same place?
> >>> I have to get a 'writer', how do I do this?
> >>
> >>The minidom docs say that DOM objects have a writexml() method:
> >>writexml(writer[,indent=""[,addindent=""[,newl=""]]])
> >>    Write XML to the writer object. The writer should have a write() method which matches that of the file object interface.
> >>
> >>This is saying that 'writer' should act like a file object. So it can just be a file object obtained by calling open(). In other words something like
> >>f = open(file_name, 'w')
> >>xmlDocument.writexml(f)
> >>f.close()
> >>
> >>should do it. If you have non-ascii characters in your XML you should use codecs.open() instead of plain open() and encode your XML as desired (probably utf-8).
> >>
> >>> Do I have to write all the data back or can I just replace the pieces I 
> >>> changed?
> >>
> >>You have to write it all back.
> >>
> >>Kent
> >>
> >>_______________________________________________
> >>Tutor maillist  -  Tutor at python.org <mailto:Tutor at python.org>
> >>http://mail.python.org/mailman/listinfo/tutor
> >>
> > 
> 
> _______________________________________________
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> http://mail.python.org/mailman/listinfo/tutor


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