I have the following toy example of an XML file. I have thousands of these. I have difficulty parsing this file.
Look at the text in second line. All my original files contain this text. When I delete i:type="Record" xmlns="http://schemas.datacontract.org/Storage" from second line (retaining the remaining text), I am able to get accelx and accely values using the code given below.
How can I parse this file with the original text?
<?xml version="1.0" encoding="utf-8"?>
<ArrayOfRecord xmlns:i="http://www.w3.org/2001/XMLSchema-instance" i:type="Record" xmlns="http://schemas.datacontract.org/Storage">
<AvailableCharts>
<Accelerometer>true</Accelerometer>
<Velocity>false</Velocity>
</AvailableCharts>
<Trics>
<Trick>
<EndOffset>PT2M21.835S</EndOffset>
<Values>
<TrickValue>
<Acceleration>26.505801694441629</Acceleration>
<Rotation>0.023379150593228679</Rotation>
</TrickValue>
</Values>
</Trick>
</Trics>
<Values>
<SensorValue>
<accelx>-3.593643144</accelx>
<accely>7.316485176</accely>
</SensorValue>
<SensorValue>
<accelx>0.31103436</accelx>
<accely>7.70408184</accely>
</SensorValue>
</Values>
</ArrayOfRecord>
Code to parse the data:
import lxml.etree as etree
tree = etree.parse(r"C:\testdel.xml")
root = tree.getroot()
val_of_interest = root.findall('./Values/SensorValue')
for sensor_val in val_of_interest:
print sensor_val.find('accelx').text
print sensor_val.find('accely').text
I asked related question here: How to extract data from xml file that is deep down the tag
Thanks
The confusion was caused by the following default namespace (namespace declared without prefix) :
xmlns="http://schemas.datacontract.org/Storage"
Note that descendants elements without prefix inherit default namespace from ancestor, implicitly. Now, to reference element in namespace, you need to map a prefix to the namespace URI, and use that prefix in your XPath :
ns = {'d': 'http://schemas.datacontract.org/Storage' }
val_of_interest = root.findall('./d:Values/d:SensorValue', ns)
for sensor_val in val_of_interest:
print sensor_val.find('d:accelx', ns).text
print sensor_val.find('d:accely', ns).text
Related
I am having problems generating a XML document using the ElementTree framework in Python 3. I tried registering the namespace before setting up the document. Right now it seems that I can generate a XML document only by adding the namespace to each element like a=Element("{full_namespace_URI}element_name") which seems tedious.
How do I setup the default namespace and can omit putting it in each element?
Any help is appreciated.
I have written a small demo program for Python 3:
from io import BytesIO
from xml.etree import ElementTree as ET
ET.register_namespace("", "urn:dslforum-org:service-1-0")
"""
desired output
==============
<?xml version='1.0' encoding='utf-8'?>
<topNode xmlns="urn:dslforum-org:service-1-0"">
<childNode>content</childNode>
</topNode>
"""
# build XML document without namespaces
a = ET.Element("topNode")
b = ET.Element("childNode")
b.text = "content"
a.append(b)
tree = ET.ElementTree(a)
# build XML document with namespaces
a_ns = ET.Element("{dsl}topNode")
b_ns = ET.Element("{dsl}childNode")
b_ns.text = "content"
a_ns.append(b_ns)
tree_ns = ET.ElementTree(a_ns)
def print_element_tree(element_tree, comment, default_namespace=None):
"""
print element tree with comment to standard out
"""
with BytesIO() as buf:
element_tree.write(buf, encoding="utf-8", xml_declaration=True,
default_namespace=default_namespace)
buf.seek(0)
print(comment)
print(buf.read().decode("utf-8"))
print_element_tree(tree, "Element Tree without XML namespace")
print_element_tree(tree_ns, "Element Tree with XML namespace", "dsl")
I believe you are overthinking this.
Registering a default namespace in your code avoids the ns0: aliases.
Registering any namespaces you will use while creating a document allows you to designate the alias used for each namespace.
To achieve your desired output, assign the namespace to your top element:
a = ET.Element("{urn:dslforum-org:service-1-0}topNode")
The preceding ET.register_namespace("", "urn:dslforum-org:service-1-0") will make that the default namespace in the document, assign it to topNode, and not prefix your tag names.
<?xml version='1.0' encoding='utf-8'?>
<topNode xmlns="urn:dslforum-org:service-1-0"><childNode>content</childNode></topNode>
If you remove the register_namespace() call, then you get this monstrosity:
<?xml version='1.0' encoding='utf-8'?>
<ns0:topNode xmlns:ns0="urn:dslforum-org:service-1-0"><childNode>content</childNode></ns0:topNode>
My xml file looks like below :-
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<Messages xmlns="URL/sampleMessages-v1">
<Header>
<TransactionId>0</TransactionId>
<RequestNo>41194812</RequestNo>
<VNo>6789</VNo>
<Source></Source>
</Header>
...
...
</Messages>
I want to read it and change the RequestNo value
<RequestNo>41194812</RequestNo> to
<RequestNo>41194000</RequestNo>
I am using ElementTree module currently. I am using windows machine currently.
I want to update the value in the same file.
Ihave tried below code :-
for elem in root:
for subelem in elem:
#print (subelem.tag)
if 'RequestNo' in subelem.tag :
#print (subelem.text)
subelem.text="41194813"
But i am not able to see the change or i dont know currently how to write this new value subelem.text="41194813" in existing xml file.
Your for loop does the job: it did replace the text correctly. The change is in your root variable. You can verify that by adding the following line right after the for loop:
ElementTree.dump(root)
Now that you have the XML updated, you will need to write that into a file:
tree.write('newfile.xml')
Where tree is the result of ElementTree.parse(). So, to put everything together:
tree = ElementTree.parse('messages.xml')
root = tree.getroot()
for elem in root:
for subelem in elem:
if 'RequestNo' in subelem.tag:
subelem.text = '41194813'
break
tree.write('messages-new.xml')
Dealing with Namespaces
Your XML document contains namespaces, so if you plan to search for a tag, you need to include the namespaces in the tag names. Here is an alternative solution which deals with namespaces:
tree = ElementTree.parse('messages.xml')
root = tree.getroot()
namespaces = {'xxx': 'URL/sampleMessages-v1'}
node = root.find('xxx:Header/xxx:RequestNo', namespaces)
if node is not None:
node.text = '41194813'
tree.write('messages-new.xml')
In the above example, I just gave your namespace the name 'xxx', it can be anything 'foo', 'bar', ... but should be used as prefix in the call to root.find().
Removing "ns0" from Output File
In order to remove "ns0" from output file, you need to register the namespace before writing:
ElementTree.register_namespace('', 'URL/sampleMessages-v1')
tree.write('messages-new.xml')
I am writing program to work on xml file and change it. But when I try to get to any part of it I get some extra part.
My xml file:
<?xml version="1.0" encoding="UTF-8"?>
<Package xmlns="http://soap.sforce.com/2006/04/metadata">
<types>
<members>sbaa__ApprovalChain__c.ExternalID__c</members>
<members>sbaa__ApprovalCondition__c.ExternalID__c</members>
<members>sbaa__ApprovalRule__c.ExternalID__c</members>
<name>CustomField</name>
</types>
<version>40.0</version>
</Package>
And I have my code:
from lxml import etree
import sys
tree = etree.parse('package.xml')
root = tree.getroot()
print( root[0][0].tag )
As output I expect to see members but I get something like this:
{http://soap.sforce.com/2006/04/metadata}members
Why do I see that url and how to stop it from showing up?
You have defined a default namespace (Wikipedia, lxml tutorial). When defined, it is a part of every child tag.
If you want to print the tag without the namespace, it's easy
tag = root[0][0].tag
print(tag[tag.find('}')+1:])
If you want to remove the namespace from XML, see this question.
I'm trying to locate fields in a SOAP xml file using lxml (3.6.0)
...
<soap:Body>
<Request xmlns="http://localhost/">
<Test>
<field1>hello</field1>
<field2>world</field2>
</Test>
</Request>
</soap:Body>
...
In this example I'm trying to find field1 and field2.
I need to add a path to the search term, to find the field:
print (myroot.find(".//{http://localhost/}field1").tag) # prints 'field1'
without it, I don't find anything
print (myroot.find("field1").tag) # finds 'None'
Is there any other way to search for the field tag (here field1) without giving path info?
Full example below:
from lxml import etree
example = """<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://schemas.xmlsoap.org/soap/envelope/" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema">
<soap:Body><Request xmlns="http://localhost/">
<Test><field1>hello</field1><field2>world</field2></Test>
</Request></soap:Body></soap:Envelope>
"""
myroot = etree.fromstring(example)
# this works
print (myroot.find(".//{http://localhost/}field1").text)
print (myroot.find(".//{http://localhost/}field2").text)
# this fails
print (myroot.find(".//field1").text)
print (myroot.find("field1").text)
Comment: The input of the SOAP request is given, I can't change any of it in real live to make things easier.
There is a way to ignore namespace when selecting element using XPath, but that isn't a good practice. Namespace is there for a reason. Anyway, there is a cleaner way to reference element in namespace i.e by using namespace prefix that was mapped to the namespace uri, instead of using the actual namespace uri every time :
.....
>>> ns = {'d': 'http://localhost/'}
>>> print (myroot.find(".//d:field1", ns).text)
hello
>>> print (myroot.find(".//d:field2", ns).text)
world
I'm trying to write a simple program to read my financial XML files from GNUCash, and learn Python in the process.
The XML looks like this:
<?xml version="1.0" encoding="utf-8" ?>
<gnc-v2
xmlns:gnc="http://www.gnucash.org/XML/gnc"
xmlns:act="http://www.gnucash.org/XML/act"
xmlns:book="http://www.gnucash.org/XML/book"
{...}
xmlns:vendor="http://www.gnucash.org/XML/vendor">
<gnc:count-data cd:type="book">1</gnc:count-data>
<gnc:book version="2.0.0">
<book:id type="guid">91314601aa6afd17727c44657419974a</book:id>
<gnc:count-data cd:type="account">80</gnc:count-data>
<gnc:count-data cd:type="transaction">826</gnc:count-data>
<gnc:count-data cd:type="budget">1</gnc:count-data>
<gnc:commodity version="2.0.0">
<cmdty:space>ISO4217</cmdty:space>
<cmdty:id>BRL</cmdty:id>
<cmdty:get_quotes/>
<cmdty:quote_source>currency</cmdty:quote_source>
<cmdty:quote_tz/>
</gnc:commodity>
Right now, i'm able to iterate and get results using
import xml.etree.ElementTree as ET
r = ET.parse("file.xml").findall('.//')
after manually cleaning the namespaces, but I'm looking for a solution that could either read the entries regardless of their namespaces OR remove the namespaces before parsing.
Note that I'm a complete noob in python, and I've read: Python and GnuCash: Extract data from GnuCash files, Cleaning an XML file in Python before parsing and python: xml.etree.ElementTree, removing "namespaces" along with ElementTree docs and I'm still lost...
I've come up with this solution:
def strip_namespaces(self, tree):
nspOpen = re.compile("<\w*:", re.IGNORECASE)
nspClose = re.compile("<\/\w*:", re.IGNORECASE)
for i in tree:
start = re.sub(nspOpen, '<', tree.tag)
end = re.sub(nspOpen, '<\/', tree.tag)
# pprint(finaltree)
return
But I'm failing to apply it. I can't seem to be able to retrieve the tag names as they appear on the file.
I think below python code will be helpfull to you.
sample.xml
<?xml version="1.0" encoding="UTF-8" standalone="yes"?>
<gnc:prodinfo xmlns:gnc="http://www.gnucash.org/XML/gnc"
xmlns:act="http://www.gnucash.org/XML/act"
xmlns:book="http://www.gnucash.org/XML/book"
xmlns:vendor="http://www.gnucash.org/XML/vendor">
<gnc:change>
<gnc:lastUpdate>2018-12-21
</gnc:lastUpdate>
</gnc:change>
<gnc:bill>
<gnc:billAccountNumber>1234</gnc:billAccountNumber>
<gnc:roles>
<gnc:id>111111</gnc:id>
<gnc:pos>2</gnc:pos>
<gnc:genid>15</gnc:genid>
</gnc:roles>
</gnc:bill>
<gnc:prodtyp>sales and service</gnc:prodtyp>
</gnc:prodinfo>
PYTHON CODE: to remove xmlns for root tag.
import xml.etree.cElementTree as ET
def xmlns(str):
str1 = str.split('{')
l=[]
for i in str1:
if '}' in i:
l.append(i.split('}')[1])
else:
l.append(i)
var = ''.join(l)
return var
tree=ET.parse('sample.xml')
root = tree.getroot()
print(root.tag) #returns root tag with xmlns as prefix
print(xmlns(root.tag)) #returns root tag with out xmlns as prefix
Output:
{http://www.gnucash.org/XML/gnc}prodinfo
prodinfo