Friday, February 14, 2014

Parsing feeds - get by attribute and value - part 2

Most developers use REST services or other data feeds that move data using XML.
This is a simple script to read online the xml file.
I used minidom but you can also use etree with ElementTree or cElementTree from etree.
I don't know if the ElementTree or cElementTree are more faster like minidom.
The script use urllib2 to open the file.
The file will show us the currency from each country.
The main goal of this script is : how to deal with attribute and value from xml files.
You can also see first part of this issue.
The structure of the xml file has also some attributes - currency.
Basicaly is something like this :
<?xml version="1.0" encoding="UTF-8"?>
-<dataset xsi:schemaLocation="http://www.bnr.ro/xsd nbrfxrates.xsd" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns="http://www.bnr.ro/xsd">
-<header>
<publisher>National Bank of Romania</Publisher>
<publishingdate>2014-02-14</PublishingDate>
<messagetype>DR</MessageType>
</Header>
-<body>
<subject>Reference rates</Subject>
<origcurrency>RON</OrigCurrency>
-<cube date="2014-02-14">
<rate currency="AED">0.8909</Rate>
<rate currency="AUD">2.9529</Rate>
<rate currency="BGN">2.2913</Rate>
...
Now let see the script :
from xml.dom import minidom as dom
import urllib2

def fetchPage(url):
    a = urllib2.urlopen(url)
    return ''.join(a.readlines())

def extract(page):
    a = dom.parseString(page)

    item = a.getElementsByTagName('Rate')

    for i in item:
        if i.hasChildNodes() == True:
                print i.getAttribute('currency')+"-"+ i.firstChild.nodeValue

if __name__=='__main__':
    page = fetchPage("http://www.bnro.ro/nbrfxrates.xml")
    extract(page)
and the output is this :
AED-0.8909
AUD-2.9529
BGN-2.2913
BRL-1.3665
CAD-2.9879
CHF-3.6655
CNY-0.5394
CZK-0.1636
DKK-0.6005
EGP-0.4701
EUR-4.4813
GBP-5.4630
HUF-1.4517
INR-0.0527
JPY-3.2148
KRW-0.3078
MDL-0.2434
MXN-0.2467
NOK-0.5365
NZD-2.7388
PLN-1.0786
RSD-0.0387
RUB-0.0932
SEK-0.5074
TRY-1.4950
UAH-0.3865
USD-3.2721
XAU-137.6798
XDR-5.0505
ZAR-0.2981

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