I have XML shaped like the following:
<?xml version="1.0" encoding="UTF-8"?>
<feed xmlns="http://www.w3.org/2005/Atom" xmlns:openSearch="http://a9.com/-/spec/opensearch/1.1/" xmlns:docs="http://schemas.google.com/docs/2007" xmlns:batch="http://schemas.google.com/gdata/batch"
<entry gd:etag=""HxYZGQVeHyt7ImBr"">
<title>Some document title I wish to find</title>
I have many entry elements, each which contains a title element. I wish to find which entry contains a title element with particular element text.
I can iterate over each item perfectly with the following code:
entry = './/{http://www.w3.org/2005/Atom}entry'
document_nodes = document_feed_xml.findall(entry)
for document_node in document_nodes:
logging.warn('entry item found!')
logging.warn(pretty_print(document_node))
logging.warn('-'*80)
This works, returning:
WARNING:root:--------------------------------------------------------------------------------
WARNING:root:entry item found!
<ns0:entry ns1:etag=""HxdWRh4MGit7ImBr"" xmlns:ns0="http://www.w3.org/2005/Atom" xmlns:ns1="http://schemas.google.com/g/2005">
<ns0:title>
Some document title
</ns0:title>
</ns0:entry>
So now I'd like to look for a 'title' element in this branch of the tree. if I look for:
title = './/{http://www.w3.org/2005/Atom}title'
title_nodes = document_node.findall(title)
for title_node in title_nodes:
logging.warn('yaaay')
logging.warn(title_node.text)
if not title_nodes:
raise ValueError('Could not find any title elements in this entry')
Edit: I originally had 'document_node[0].findall' from some debugging. Removing this, the code above works. This was the cause of the error - thanks the the gent below for spotting this!
This raises the error for no title nodes.
These results seem odd, as:
- I can clearly see that element, with that namespace, in the document
- I can even run findall() for title directly, using that namespace, and see the results
I've wondered about the possibility of findall() returning objects that are of a different class from it's input, however running 'type' on either object merely returns 'instance' as the type. Quality programming there ElementTree.
Although LXML has better documentation, better xpath support, and better code, for technical reasons, I cannot use LXML, so I am forced to use ElementTree.
The problem is that document_node[0] in your code already references the title element, and looking through its children returns nothing.
Related
Given the xml
xmlstr = '''
<myxml>
<Description id="10">
<child info="myurl"/>
</Description>
</myxml>'
I'd like to get the id of Description only where child has an attribute of info.
import xml.etree.ElementTree as ET
root = ET.fromstring(xmlstr)
a = root.find(".//Description/[child/#info]")
print(a.attrib)
and changing the find to .//Description/[child[#info]]
both return an error of:
SyntaxError: invalid predicate
I know that etree only supports a subset of xpath, but this doesn't seem particularly weird - should this work? If so, what have I done wrong?!
Changing the find to .//Description/[child] does work, and returns
{'id': '10'}
as expected
You've definitely hit that XPath limited support limitation as, if we look at the source directly (looking at 3.7 source code), we could see that while parsing the Element Path expression, only these things in the filters are considered:
[#attribute] predicate
[#attribute='value']
[tag]
[.='value'] or [tag='value']
[index] or [last()] or [last()-index]
Which means that both of your rather simple expressions are not supported.
If you really want/need to stick with the built-in ElementTree library, one way to solve this would be with finding all Description tags via .findall() and filtering the one having a child element with info attribute.
You can also get those values as keys, which makes it a bit more structured approach to gather data:
import xml.etree.ElementTree as ET
root = ET.fromstring(xmlstr)
wht =root.find(".//Description")
wht.keys() #--> ['id']
wht.get('id') # --> '10'
I am trying to parse a .kml file into Python using the xml module (after failing to make this work in BeautifulSoup, which I use for HTML).
As this is my first time doing this, I followed the official tutorial and all goes well until I try to construct an iterator to extract my data by root iteration:
from lxml import etree
tree=etree.parse('kmlfile')
Here is the example from the tutorial I am trying to emulate:
If you know you are only interested in a single tag, you can pass its name to getiterator() to have it filter for you:
for element in root.getiterator("child"):
print element.tag, '-', element.text
I would like to get all data under 'Placemark', so I tried
for i in tree.getiterterator("Placemark"):
print i, type(i)
which doesn't give me anything. What does work is:
for i in tree.getiterterator("{http://www.opengis.net/kml/2.2}Placemark"):
print i, type(i)
I don't understand how this comes about. The www.opengis.net is listed in the tag at the beginning of the document (kml xmlns="http://www.opengis.net/kml/2.2"...) , but I don't understand
how the part in {} relates to my specific example at all
why it is different from the tutorial
and what I am doing wrong
Any help is much appreciated!
Here is my solution.
So, the most important thing to do is read this as posted by Tomalak. It's a really good description of namespaces and easy to understand.
We are going to use XPath to navigate the XML document. Its notation is similar to file systems, where parents and descendants are separated by slashes /. The syntax is explained here, but note that some commands are different for the lxml implementation.
###Problem
Our goal is to extract the city name: the content of <name> which is under <Placemark>. Here's the relevant XML:
<Placemark> <name>CITY NAME</name>
The XPath equivalent to the non-functional code I posted above is:
tree=etree.parse('kml document')
result=tree.xpath('//Placemark/name/text()')
Where the text() part is needed to get the text contained in the location //Placemark/name.
Now this doesn't work, as Tomalak pointed out, cause the name of these two nodes are actually {http://www.opengis.net/kml/2.2}Placemark and {http://www.opengis.net/kml/2.2}name. The part in curly brackets is the default namespace. It does not show up in the actual document (which confused me) but it is defined at the beginning of the XML document like this:
xmlns="http://www.opengis.net/kml/2.2"
###Solution
We can supply namespaces to xpath by setting the namespaces argument:
xpath(X, namespaces={prefix: namespace})
This is easy enough for the namespaces that have actual prefixes, in this document for instance <gx:altitudeMode>relativeToSeaFloor</gx:altitudeMode> where the gx prefix is defined in the document as xmlns:gx="http://www.google.com/kml/ext/2.2".
However, Xpath does not understand what a default namespace is (cf docs). Therefore, we need to trick it, like Tomalak suggested above: We invent a prefix for the default and add it to our search terms. We can just call it kml for instance. This piece of code actually does the trick:
tree.xpath('//kml:Placemark/kml:name/text()', namespaces={"kml":"http://www.opengis.net/kml/2.2"})
The tutorial mentions that there is also an ETXPath method, that works just like Xpath except that one writes the namespaces out in curly brackets instead of defining them in a dictionary. Thus, the input would be of the style {http://www.opengis.net/kml/2.2}Placemark.
My question is regarding how to get information stored in a tag which allows for no closing tag. Here's the relevant xml:
<?xml version="1.0" encoding="UTF-8"?>
<uws:job>
<uws:results>
<uws:result id="2014-03-03T15:42:31:1337" xlink:href="http://www.cosmosim.org/query/index/stream/table/2014-03-03T15%3A42%3A31%3A1337/format/csv" xlink:type="simple"/>
</uws:results>
</uws:job>
I'm looking to extract the xlink:href url here. As you can see the uws:result tag requires no closing tag. Additionally, having the 'uws:' makes it a bit tricky to handle them when working in python. Here's what I've tried so far:
from lxml import etree
root = etree.fromstring(xmlresponse.content)
url = root.find('{*}results').text
Where xmlresponse.content is the xml data to be parsed. What this returns is
'\n '
which indicates that it's only finding the newline character, since what I'm really after is contained within a tag inside the results tag. Any ideas would be greatly appreciated.
You found the right node; you extracted the data incorrectly. Instead of
url = root.find('{*}results').text
you really want
url = root.find('{*}results').get('attribname', 'value_to_return_if_not_present')
or
url = root.find('{*}results').attrib['attribname']
(which will throw an exception if not present).
Because of the namespace on the attribute itself, you will probably need to use the {ns}attrib syntax to look it up too.
You can dump out the attrib dictionary and just copy the attribute name out too.
text is actually the space between elements, and is not normally used but is supported both for spacing (like etreeindent) and some special cases.
I'm trying to get to a specific tag in an xml file loaded into a BS object, but when I get to a specific tag, BS is going into the first child when I try an access the children using square brackets '[]'.
for instance, given the xml below, I should get to conditionalBlocks using this python code:
reportPages = reportpages.findAll('page')
for reportPage in reportPages:
contents = reportPage.findAll('pagebody')[0].find_all('contents') #[0].findAll()
print "contents; ", contents
conditionalBlocks = contents[0].find_all('conditionalBlocks')
print "conblox; ", conditionalBlocks
Now at print "contents, "... I get the output:
<contents>
<textitem>
<datasource>
<staticvalue>Foods Management Guide for </staticvalue>
</datasource>
<style>
<defaultStyles>
<defaultStyle refStyle="wwtxtt"/>
</style>
</textitem>
</contents>
Which is incomplete as far as I can tell; it only has the contents of the first textItem tag within the contents tag and not the other tags that come after
also the line at print "conblox; ", ... I get the output;
conblox; []
saying that NO conditionalBlocks tag was found, which; If I look at the xml being read in (see below); is impossible.
I can't understand how it finds the first tag, but not the others, ie: conditionalBlocks.
Can someone help explain this please?
here's the XML I'm working with (shortened to make it easy to read):
<reportPages>
<page name="Page1">
<pageBody>
<contents>
<textItem>...</textItem>
<textItem>...</textItem>
<block>...</block>
<block>...</block>
<conditionalBlocks>
<conditionalBlockDefault>...</conditionalBlockDefault>
<conditionalBlockCases refVariable="vView">
<conditionalBlock refVariableValue="Item Rands">...</conditionalBlock>
<conditionalBlock refVariableValue="Item Units">...</conditionalBlock>
</conditionalBlockCases>
</conditionalBlocks>
</contents>
<style>...</style>
</pageBody>
<pageHeader>...</pageHeader>
<pageFooter>...</pageFooter>
<style>...</style>
<conditionalRender refVariable="vView">...</conditionalRender>
</page>
<page name="Page2">...</page>
</reportPages>
What happens is and cite :
Using a tag name as an attribute will give you only the first tag by that name.
If you want to select all the tags you need to use the find_all method because the find_all scans the entire document looking for results.
If find_all can’t find anything, it returns an empty list.
I recommend you read the BeautifulSoup documentation for more details.
I'm just trying to write a simple program to allow me to parse some of the following XML.
So far in following examples I am not getting the results I'm looking for.
I encounter many of these XML files and I generally want the info after a handful of tags.
What's the best way using elementtree to be able to do a search for <Id> and grab what ever info is in that tag. I was trying things like
for Reel in root.findall('Reel'):
... id = Reel.findtext('Id')
... print id
Is there a way just to look for every instance of <Id> and grab the urn: etc that comes after it? Some code that traverses everything and looks for <what I want> and so on.
This is a very truncated version of what I usually deal with.
This didn't get what I wanted at all. Is there an easy just to match <what I want> in any XML file and get the contents of that tag, or do i need to know the structure of the XML well enough to know its relation to Root/child etc?
<Reel>
<Id>urn:uuid:632437bc-73f9-49ca-b687-fdb3f98f430c</Id>
<AssetList>
<MainPicture>
<Id>urn:uuid:46afe8a3-50be-4986-b9c8-34f4ba69572f</Id>
<EditRate>24 1</EditRate>
<IntrinsicDuration>340</IntrinsicDuration>
<EntryPoint>0</EntryPoint>
<Duration>340</Duration>
<FrameRate>24 1</FrameRate>
<ScreenAspectRatio>2048 858</ScreenAspectRatio>
</MainPicture>
<MainSound>
<Id>urn:uuid:1fce0915-f8c7-48a7-b023-36e204a66ed1</Id>
<EditRate>24 1</EditRate>
<IntrinsicDuration>340</IntrinsicDuration>
<EntryPoint>0</EntryPoint>
<Duration>340</Duration>
</MainSound>
</AssetList>
</Reel>
#Mata that worked perfectly, but when I tried to use that for different values on another XML file I fell flat on my face. For instance, what about this section of a file.I couldn't post the whole thing unfortunately. What if I want to grab what comes after KeyId?
<?xml version="1.0" encoding="UTF-8" standalone="no" ?><DCinemaSecurityMessage xmlns="http://www.digicine.com/PROTO-ASDCP-KDM-20040311#" xmlns:dsig="http://www.w3.org/2000/09/xmldsig#" xmlns:enc="http://www.w3.org/2001/04/xmlenc#">
<!-- Generated by Wailua Version 0.3.20 -->
<AuthenticatedPublic Id="ID_AuthenticatedPublic">
<MessageId>urn:uuid:7bc63f4c-c617-4d00-9e51-0c8cd6a4f59e</MessageId>
<MessageType>http://www.digicine.com/PROTO-ASDCP-KDM-20040311#</MessageType>
<AnnotationText>SPIDERMAN-3_FTR_S_EN-XX_US-13_51_4K_PH_20070423_DELUXE ~ KDM for Quvis-10010.pem</AnnotationText>
<IssueDate>2007-04-29T04:13:43-00:00</IssueDate>
<Signer>
<dsig:X509IssuerName>dnQualifier=BzC0n/VV/uVrl2PL3uggPJ9va7Q=,CN=.deluxe-admin-c,OU=.mxf-j2c.ca.cinecert.com,O=.ca.cinecert.com</dsig:X509IssuerName>
<dsig:X509SerialNumber>10039</dsig:X509SerialNumber>
</Signer>
<RequiredExtensions>
<Recipient>
<X509IssuerSerial>
<dsig:X509IssuerName>dnQualifier=RUxyQle0qS7qPbcNRFBEgVjw0Og=,CN=SM.QuVIS.com.001,OU=QuVIS Digital Cinema,O=QuVIS.com</dsig:X509IssuerName>
<dsig:X509SerialNumber>363</dsig:X509SerialNumber>
</X509IssuerSerial>
<X509SubjectName>CN=SM MD LE FM.QuVIS_CinemaPlayer-3d_10010,OU=QuVIS,O=QuVIS.com,dnQualifier=3oBfjTfx1me0p1ms7XOX\+eqUUtE=</X509SubjectName>
</Recipient>
<CompositionPlaylistId>urn:uuid:336263da-e4f1-324e-8e0c-ebea00ff79f4</CompositionPlaylistId>
<ContentTitleText>SPIDERMAN-3_FTR_S_EN-XX_US-13_51_4K_PH_20070423_DELUXE</ContentTitleText>
<ContentKeysNotValidBefore>2007-04-30T05:00:00-00:00</ContentKeysNotValidBefore>
<ContentKeysNotValidAfter>2007-04-30T10:00:00-00:00</ContentKeysNotValidAfter>
<KeyIdList>
<KeyId>urn:uuid:9851b0f6-4790-0d4c-a69d-ea8abdedd03d</KeyId>
<KeyId>urn:uuid:8317e8f3-1597-494d-9ed8-08a751ff8615</KeyId>
<KeyId>urn:uuid:5d9b228d-7120-344c-aefc-840cdd32bbfc</KeyId>
<KeyId>urn:uuid:1e32ccb2-ab0b-9d43-b879-1c12840c178b</KeyId>
<KeyId>urn:uuid:44d04416-676a-2e4f-8995-165de8cab78d</KeyId>
<KeyId>urn:uuid:906da0c1-b0cb-4541-b8a9-86476583cdc4</KeyId>
<KeyId>urn:uuid:0fe2d73a-ebe3-9844-b3de-4517c63c4b90</KeyId>
<KeyId>urn:uuid:862fa79a-18c7-9245-a172-486541bef0c0</KeyId>
<KeyId>urn:uuid:aa2f1a88-7a55-894d-bc19-42afca589766</KeyId>
<KeyId>urn:uuid:59d6eeff-cd56-6245-9f13-951554466626</KeyId>
<KeyId>urn:uuid:14a13b1a-76ba-764c-97d0-9900f58af53e</KeyId>
<KeyId>urn:uuid:ccdbe0ae-1c3f-224c-b450-947f43bbd640</KeyId>
<KeyId>urn:uuid:dcd37f10-b042-8e44-bef0-89bda2174842</KeyId>
<KeyId>urn:uuid:9dd7103e-7e5a-a840-a15f-f7d7fe699203</KeyId>
</KeyIdList>
</RequiredExtensions>
<NonCriticalExtensions/>
</AuthenticatedPublic>
<AuthenticatedPrivate Id="ID_AuthenticatedPrivate"><enc:EncryptedKey xmlns:enc="http://www.w3.org/2001/04/xmlenc#">
<enc:EncryptionMethod Algorithm="http://www.w3.org/2001/04/xmlenc#rsa-oaep-mgf1p">
<ds:DigestMethod xmlns:ds="http://www.w3.org/2000/09/xmldsig#" Algorithm="http://www.w3.org/2000/09/xmldsig#sha1"/>
</enc:EncryptionMethod>
The expression Reel.findtext('Id') only matches direct children of Reel. If you want to find all Id tags in your xml document, you can just use:
ids = [id.text for id in Reel.findall(".//Id")]
This would give you a list of all text nodes of all Id tags which are children of Reel.
edit:
Your updated example uses namespaces, in this case KeyId is in the default namespace (http://www.digicine.com/PROTO-ASDCP-KDM-20040311#), so to search for it you need to include it in your search:
from xml.etree import ElementTree
doc = ElementTree.parse('test.xml')
nsmap = {'ns': 'http://www.digicine.com/PROTO-ASDCP-KDM-20040311#'}
ids = [id.text for id in doc.findall(".//ns:KeyId", namespaces=nsmap)]
print(ids)
...
The xpath subset ElementTree supports is rather limited. If you want a more complete support, you should use lxml instead, it's xpath support is way more complete.
For example, using xpath to search for all KeyId tags (ignoring namespaces) and returning their text content directly:
from lxml import etree
doc = etree.parse('test.xml')
ids = doc.xpath(".//*[local-name()='KeyId']/text()")
print(ids)
...
It sounds like XPath might be right up your alley - it will let you query your XML document for exactly what you're looking for, as long as you know the structure.
Here's what I needed to do. This works for finding whatever I need.
for node in tree.getiterator():
... if 'KeyId' in node.tag:
... mylist = node.tag
... print(mylist)
...