在Python3中解析循环中的XML数据以创建多个对象

Question

我有以下XML结构：

<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>

我想把它们读入python3中创建的对象中。你知道吗

我有以下循环：

# 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)

但正如您所看到的，我希望以一种好的方式从XML文件中获取数据，而不是自己硬编码行星。因此，与其说“水星”，不如说它穿过树，把每个天体的值转化为变量，然后创建一个物体。你知道吗

我无法理解的是XML阅读部分。无论我尝试了什么，我都无法循环通过级别将值读入变量。我已经试过BeautifulSoup，lxml，ET了，但是没有成功。你知道吗

一些试验：

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

或者

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)

每一个都会产生错误。应该有一个简单的方法。你知道吗

有什么建议吗？你知道吗

编辑：因此，通过以下步骤，我可以联系到两个孩子，但不能再联系了：

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

输出：

stars {}
planets {}

如何在这些函数中循环并检索值？你知道吗

Answer 1

这段代码使用etree工作。缺少一行，该行仅返回item元素，这些元素的name设置为某个值。你知道吗

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, ...)

从这里你应该可以自己解决剩下的问题。希望有帮助。你知道吗

Answer 2

这里有一个简单的方法来迭代这个数据结构。为了保持代码的独立性，我直接从字符串而不是从文件中读取XML。你知道吗

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()

输出

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'

---

这个变体将数据加载到包含两个列表的字典中，一个是恒星列表，另一个是行星列表。这些列表中的每一个都包含该类别中每个主体的字典。我们可以使用json模块很好地打印数据。你知道吗

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))

输出

 {
    "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"
        }
    ]
}

Answer 3

首先，您可以找到行星和恒星元素，将它们添加到列表中并从中选择第一个值。你知道吗

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")