从Python中的ADO.Net数据服务XML解析元数据属性

Question

我想在将数据填入数据库表之前将一些XML放入熊猫数据框中。我已经看过元素树和lxml，但这些例子非常简单，我似乎无法将它们推断为复杂的东西。我了解XML我只是不知道如何深入到我需要的东西。下面是一个示例。

我在<m:properties>的东西之后。所以NEW_DATE = 1997-01-02T00：00：00，BC_1YEAR = 5.630000114440918等等是数据库中的内容。请注意BC_1MONTH = NULL，并且不像其他节点。

<?xml version="1.0" encoding="utf-8" standalone="yes"?> 
<feed xml:base="http://data.treasury.gov/Feed.svc/" xmlns:d="http://schemas.microsoft.com/ado/2007/08/dataservices" xmlns:m="http://schemas.microsoft.com/ado/2007/08/dataservices/metadata" xmlns="http://www.w3.org/2005/Atom"> 
    <title type="text">DailyTreasuryYieldCurveRateData</title> 
    <id>http://data.treasury.gov/feed.svc/DailyTreasuryYieldCurveRateData</id> 
    <updated>2017-10-30T20:31:53Z</updated> 
    <link rel="self" title="DailyTreasuryYieldCurveRateData" href="DailyTreasuryYieldCurveRateData" /> 
    <entry> 
    <id>http://data.treasury.gov/Feed.svc/DailyTreasuryYieldCurveRateData(1)</id> 
    <title type="text"></title> 
    <updated>2017-10-30T20:31:53Z</updated> 
    <author> 
     <name /> 
    </author> 
    <link rel="edit" title="DailyTreasuryYieldCurveRateDatum" href="DailyTreasuryYieldCurveRateData(1)" /> 
    <category term="TreasuryDataWarehouseModel.DailyTreasuryYieldCurveRateDatum" scheme="http://schemas.microsoft.com/ado/2007/08/dataservices/scheme" /> 
    <content type="application/xml"> 
     <m:properties> 
     <d:Id m:type="Edm.Int32">1</d:Id> 
     <d:NEW_DATE m:type="Edm.DateTime">1997-01-02T00:00:00</d:NEW_DATE> 
     <d:BC_1MONTH m:type="Edm.Double" m:null="true" /> 
     <d:BC_3MONTH m:type="Edm.Double">5.190000057220459</d:BC_3MONTH> 
     <d:BC_6MONTH m:type="Edm.Double">5.3499999046325684</d:BC_6MONTH> 
     <d:BC_1YEAR m:type="Edm.Double">5.630000114440918</d:BC_1YEAR> 
     <d:BC_2YEAR m:type="Edm.Double">5.96999979019165</d:BC_2YEAR> 
     <d:BC_3YEAR m:type="Edm.Double">6.130000114440918</d:BC_3YEAR> 
     <d:BC_5YEAR m:type="Edm.Double">6.3000001907348633</d:BC_5YEAR> 
     <d:BC_7YEAR m:type="Edm.Double">6.4499998092651367</d:BC_7YEAR> 
     <d:BC_10YEAR m:type="Edm.Double">6.5399999618530273</d:BC_10YEAR> 
     <d:BC_20YEAR m:type="Edm.Double">6.8499999046325684</d:BC_20YEAR> 
     <d:BC_30YEAR m:type="Edm.Double">6.75</d:BC_30YEAR> 
     <d:BC_30YEARDISPLAY m:type="Edm.Double">0</d:BC_30YEARDISPLAY> 
     </m:properties> 
    </content> 
    </entry> 
</feed> 

如果您有关于此的一篇好文章的链接，那也将不胜感激。

下面是我的工作代码：从达菲的代码收到

import xml.etree.ElementTree as ET 
import pandas as pd 

xml_data = open('/path/user_agents.xml').read() 

def xml2df(xml_data): 
    root = ET.XML(xml_data) # element tree 
    all_records = [] 
    for i, child in enumerate(root): 
     record = {} 
     for subchild in child: 
      record[subchild.tag] = subchild.text 
      all_records.append(record) 
    return pd.DataFrame(all_records) 

错误消息：

Traceback (most recent call last): 
    File "C:/Users/Bob/Desktop/temp/yield curve script.py", line 25, in <module> 
    xml2dict(xml_data) 
    File "C:/Users/Bob/Desktop/temp/yield curve script.py", line 13, in xml2dict 
    root = lxml.etree.parse(xml_file) 
    File "src\lxml\lxml.etree.pyx", line 3427, in lxml.etree.parse (src\lxml\lxml.etree.c:81100) 
    File "src\lxml\parser.pxi", line 1811, in lxml.etree._parseDocument (src\lxml\lxml.etree.c:117831) 
    File "src\lxml\parser.pxi", line 1837, in lxml.etree._parseDocumentFromURL (src\lxml\lxml.etree.c:118178) 
    File "src\lxml\parser.pxi", line 1741, in lxml.etree._parseDocFromFile (src\lxml\lxml.etree.c:117090) 
    File "src\lxml\parser.pxi", line 1138, in lxml.etree._BaseParser._parseDocFromFile (src\lxml\lxml.etree.c:111636) 
    File "src\lxml\parser.pxi", line 595, in lxml.etree._ParserContext._handleParseResultDoc (src\lxml\lxml.etree.c:105092) 
    File "src\lxml\parser.pxi", line 706, in lxml.etree._handleParseResult (src\lxml\lxml.etree.c:106800) 
    File "src\lxml\parser.pxi", line 633, in lxml.etree._raiseParseError (src\lxml\lxml.etree.c:105611) 
OSError: Error reading file '<?xml version="1.0" encoding="utf-8" standalone="yes"?> 

Answer 1

import lxml.etree 
import datetime 

nsmap = { 
    'm': 'http://schemas.microsoft.com/ado/2007/08/dataservices/metadata', 
    'd': 'http://schemas.microsoft.com/ado/2007/08/dataservices' 
} 
m_null = ('{%s}null' % nsmap['m']) 
m_type = ('{%s}type' % nsmap['m']) 

type_handlers = { 
    'Edm.Double': float, 
    'Edm.Int32': int, 
    'Edm.DateTime': lambda s: datetime.datetime.strptime(s.translate(None, ':-'), "%Y%m%dT%H%M%S"), 
} 

def xml2dict(xml_file): 
    root = lxml.etree.parse(xml_file) 
    result = {} 
    for properties_el in root.xpath('//m:properties', namespaces=nsmap): 
     for child in properties_el.getchildren(): 
      tag = child.tag.split('}',1)[-1] # split the namespace off the tag 
      if child.attrib.get(m_null): 
       value = None 
      else: 
       value = child.text 
       type_handler = type_handlers.get(child.attrib.get(m_type)) 
       if type_handler is not None: 
        value = type_handler(value) 
      result[tag] = value 
    return result 

...正常返回，为您的数据：

{'BC_10YEAR': 6.539999961853027, 
'BC_1MONTH': None, 
'BC_1YEAR': 5.630000114440918, 
'BC_20YEAR': 6.849999904632568, 
'BC_2YEAR': 5.96999979019165, 
'BC_30YEAR': 6.75, 
'BC_30YEARDISPLAY': 0.0, 
'BC_3MONTH': 5.190000057220459, 
'BC_3YEAR': 6.130000114440918, 
'BC_5YEAR': 6.300000190734863, 
'BC_6MONTH': 5.349999904632568, 
'BC_7YEAR': 6.449999809265137, 
'Id': 1, 
'NEW_DATE': datetime.datetime(1997, 1, 2, 0, 0)}