0

I have the following XML structure:

<celestialBodies>
<stars>
    <star>
        <item name="Name">Sun</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </star>
</stars>
<planets>  
    <planet>
        <item name="Name">Mercury</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Venus</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Earth</item>
        <item name="Distance from the Earth">0</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Mars</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Jupiter</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Saturn</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Uranus</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Neptune</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Pluto</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
</planets>  
</celestialBodies>

and I would like to read each of these into a created object in Python 3.

I have the following loop:

# Create the solar system
celestialBodies = list()
for i in range(10):
    planet = Planet("Mercury", 1000000, 0.5, 0.1, ['Moon A', 'Moon B'], ['Hydrogen, Nitrogen'], 8, 0.15)
    celestialBodies.append(planet)

but as you can see, instead of hardcoding the planets myself, I would like to get the data from the XML file in a nice way. So instead of me saying "Mercury", it should traverse through the tree and get the values of each celestial body into the variables and create the object.

What I can't get it through is the XML reading part. No matter what I tried I could not loop through the levels to read the values into the variables. I've already tried BeautifulSoup, lxml, ET but no luck.

Some trials:

   root = lxml.etree.fromstring('planet_info.xml')
   results = root.findall('planets')
   textnumbers = [r.find('planet/name').text for r in results]
   print(textnumbers)

or

solarSystem = ET.parse('planet_info.xml')
celestialBodies = solarSystem.getroot()
for bodies in celestialBodies:
    for star in bodies[0]:
        print(star.tag, star.attrib, star.nodeValue)

with each resulting with errors. There should be a straightforward way of doing this.

Any suggestions?

EDIT: So with the following I am able to reach the two children but no more:

   # Get the data from the XML
   solarSystem = ET.parse('planet_info.xml')
   celestialBodies = solarSystem.getroot()
   for bodies in celestialBodies:
       print(bodies.tag, bodies.attrib)

output: 

stars {}
planets {}

How to loop inside these and retrieve the values though?

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1
  • Your XML structure could exploit the possibilities of the format better than using just one universal item element. Commented Aug 3, 2018 at 8:22

3 Answers 3

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2

Firstly you can find planets and stars elements, add them to list and choose first values from it.

import xml.etree.ElementTree as ET  
dump = ET.parse('planet_info.xml') 
root = dump.getroot()  
planet_name = star_name = planet_list = []  
for content in root:
    planet_name = content.findall("planet")
    star_name = content.findall("star")
    if planet_name:
        for planet in planet_name:
             planet_list.append(Planet(planet[0].text, planet[1].text, etc)
    elif star_name:
        for star in star_name:
            planet_list.append(Planet(star[0].text, star[1].text, etc)
    else:
        print("Nothing")
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Comments

2

This code using etree works. You are missing one line that returns only the item elements which have name set to some value.

import xml.etree.ElementTree as ET

root = ET.parse(PATH_TO_YOUR_FILE)
planets = root.findall('./planets/planet')

planets_list = []
for planet in planets:
        name = planet.find("./item[@name='Name']").text
        d = planet.find("./item[@name='Distance from the Earth']").text
        //...
        planets_list.append(Planet(name, d, ...)

From here you should be able to solve the rest yourself. Hope it helps.

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2 Comments

I get the error of AttributeError: 'xml.etree.ElementTree.Element' object has no attribute 'name'
which version of etree/python are you using?
0

Here''s a simple way to iterate over that data structure. To keep the code self-contained, I read the XML directly from a string, rather than from a file.

import xml.etree.ElementTree as ET

data = '''\
<?xml version="1.0"?>
<celestialBodies>
<stars>
    <star>
        <item name="Name">Sun</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </star>
</stars>
<planets>  
    <planet>
        <item name="Name">Mercury</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Venus</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Earth</item>
        <item name="Distance from the Earth">0</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Mars</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Jupiter</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Saturn</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Uranus</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Neptune</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
    <planet>
        <item name="Name">Pluto</item>
        <item name="Distance from the Earth">100000</item>
        <item name="Size">9</item>
        <item name="Moons">A,B,C</item>
        <item name="Gravity">0.4</item>
        <item name="Elements Found">H, HE, C</item>
        <item name="Orbiting Time">15</item>
        <item name="Day Time">12</item>
    </planet>
</planets>  
</celestialBodies>
'''

root = ET.fromstring(data)

for kind in root:
    print(kind.tag)
    for child in kind:
        print(' '*2, child.tag)
        for item in child:
            print(' '*4, '{!r}: {!r}'.format(item.attrib['name'], item.text))
        print()

output

stars
   star
     'Name': 'Sun'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE'
     'Orbiting Time': '15'
     'Day Time': '12'

planets
   planet
     'Name': 'Mercury'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Venus'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Earth'
     'Distance from the Earth': '0'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Mars'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Jupiter'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Saturn'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Uranus'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Neptune'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

   planet
     'Name': 'Pluto'
     'Distance from the Earth': '100000'
     'Size': '9'
     'Moons': 'A,B,C'
     'Gravity': '0.4'
     'Elements Found': 'H, HE, C'
     'Orbiting Time': '15'
     'Day Time': '12'

This variation loads the data into a dictionary containing two lists, one for stars & one for planets. Each of those lists contains a dictionary for each body found in that category. We can use the json module to print the data nicely.

import xml.etree.ElementTree as ET
import json

root = ET.fromstring(data)

bodies = {}
for kind in root:
    bodies[kind.tag] = bodylist = []
    for child in kind:
        bodylist.append({item.attrib['name']: item.text for item in child})

print(json.dumps(bodies, indent=4))

output

 {
    "stars": [
        {
            "Name": "Sun",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE",
            "Orbiting Time": "15",
            "Day Time": "12"
        }
    ],
    "planets": [
        {
            "Name": "Mercury",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Venus",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Earth",
            "Distance from the Earth": "0",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Mars",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Jupiter",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Saturn",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Uranus",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Neptune",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        },
        {
            "Name": "Pluto",
            "Distance from the Earth": "100000",
            "Size": "9",
            "Moons": "A,B,C",
            "Gravity": "0.4",
            "Elements Found": "H, HE, C",
            "Orbiting Time": "15",
            "Day Time": "12"
        }
    ]
}
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