如何在 Python 中解析此 XML 响应？

Question

这是我的 XML 文件：

<?xml version="1.0" ?>
<Items>
    <Item>
        <ASIN>3570102769</ASIN>
        <DetailPageURL>http://www.amazon.de/Inside-IS-Tage-Islamischen-Staat/dp/3570102769%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3D3570102769</DetailPageURL>
        <ItemLinks>
            <ItemLink>
                <Description>Add To Wishlist</Description>
                <URL>http://www.amazon.de/gp/registry/wishlist/add-item.html%3Fasin.0%3D3570102769%26SubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3570102769</URL>
            </ItemLink>
            <ItemLink>
                <Description>Tell A Friend</Description>
                <URL>http://www.amazon.de/gp/pdp/taf/3570102769%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3570102769</URL>
            </ItemLink>
            <ItemLink>
                <Description>All Customer Reviews</Description>
                <URL>http://www.amazon.de/review/product/3570102769%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3570102769</URL>
            </ItemLink>
            <ItemLink>
                <Description>All Offers</Description>
                <URL>http://www.amazon.de/gp/offer-listing/3570102769%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3570102769</URL>
            </ItemLink>
        </ItemLinks>
        <ItemAttributes>
            <Author>Jürgen Todenhöfer</Author>
            <Binding>Gebundene Ausgabe</Binding>
            <EAN>9783570102763</EAN>
            <EANList>
                <EANListElement>9783570102763</EANListElement>
            </EANList>
            <ISBN>3570102769</ISBN>
            <IsEligibleForTradeIn>1</IsEligibleForTradeIn>
            <ItemDimensions>
                <Height Units="hundredths-inches">874</Height>
                <Length Units="hundredths-inches">575</Length>
                <Width Units="hundredths-inches">126</Width>
            </ItemDimensions>
            <Label>C. Bertelsmann Verlag</Label>
            <Languages>
                <Language>
                    <Name>Deutsch</Name>
                    <Type>Published</Type>
                </Language>
                <Language>
                    <Name>Deutsch</Name>
                    <Type>Original</Type>
                </Language>
                <Language>
                    <Name>Deutsch</Name>
                    <Type>Unbekannt</Type>
                </Language>
            </Languages>
            <ListPrice>
                <Amount>1799</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 17,99</FormattedPrice>
            </ListPrice>
            <Manufacturer>C. Bertelsmann Verlag</Manufacturer>
            <ManufacturerMinimumAge Units="months">192</ManufacturerMinimumAge>
            <NumberOfPages>288</NumberOfPages>
            <PackageDimensions>
                <Height Units="hundredths-inches">118</Height>
                <Length Units="hundredths-inches">567</Length>
                <Weight Units="hundredths-pounds">93</Weight>
                <Width Units="hundredths-inches">252</Width>
            </PackageDimensions>
            <PackageQuantity>1</PackageQuantity>
            <ProductGroup>Book</ProductGroup>
            <ProductTypeName>ABIS_BOOK</ProductTypeName>
            <PublicationDate>2015-04-27</PublicationDate>
            <Publisher>C. Bertelsmann Verlag</Publisher>
            <Studio>C. Bertelsmann Verlag</Studio>
            <Title>Inside IS - 10 Tage im 'Islamischen Staat'</Title>
            <TradeInValue>
                <Amount>930</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 9,30</FormattedPrice>
            </TradeInValue>
        </ItemAttributes>
        <OfferSummary>
            <LowestNewPrice>
                <Amount>1799</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 17,99</FormattedPrice>
            </LowestNewPrice>
            <LowestUsedPrice>
                <Amount>1390</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 13,90</FormattedPrice>
            </LowestUsedPrice>
            <LowestCollectiblePrice>
                <Amount>4999</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 49,99</FormattedPrice>
            </LowestCollectiblePrice>
            <TotalNew>56</TotalNew>
            <TotalUsed>8</TotalUsed>
            <TotalCollectible>1</TotalCollectible>
            <TotalRefurbished>0</TotalRefurbished>
        </OfferSummary>
        <Offers>
            <TotalOffers>1</TotalOffers>
            <TotalOfferPages>1</TotalOfferPages>
            <MoreOffersUrl>http://www.amazon.de/gp/offer-listing/3570102769%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3570102769</MoreOffersUrl>
            <Offer>
                <OfferAttributes>
                    <Condition>New</Condition>
                </OfferAttributes>
                <OfferListing>
                    <OfferListingId>9KHCZj9qtL6ucVBPASfXaryQjU8tWbc0n%2F3F4F7GraOKW6Csji2OxpD93%2FkoHwgIGQctlnrtx4RWIeJULAcvvsFhiopFi08JdsZ%2FeO3u6g0%3D</OfferListingId>
                    <Price>
                        <Amount>1799</Amount>
                        <CurrencyCode>EUR</CurrencyCode>
                        <FormattedPrice>EUR 17,99</FormattedPrice>
                    </Price>
                    <Availability>Gewöhnlich versandfertig in 24 Stunden</Availability>
                    <AvailabilityAttributes>
                        <AvailabilityType>now</AvailabilityType>
                        <MinimumHours>0</MinimumHours>
                        <MaximumHours>0</MaximumHours>
                    </AvailabilityAttributes>
                    <IsEligibleForSuperSaverShipping>1</IsEligibleForSuperSaverShipping>
                </OfferListing>
            </Offer>
        </Offers>
    </Item>
    <Item>
        <ASIN>3813506479</ASIN>
        <DetailPageURL>http://www.amazon.de/Altes-Land-Roman-D%C3%B6rte-Hansen/dp/3813506479%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D165953%26creativeASIN%3D3813506479</DetailPageURL>
        <ItemLinks>
            <ItemLink>
                <Description>Add To Wishlist</Description>
                <URL>http://www.amazon.de/gp/registry/wishlist/add-item.html%3Fasin.0%3D3813506479%26SubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3813506479</URL>
            </ItemLink>
            <ItemLink>
                <Description>Tell A Friend</Description>
                <URL>http://www.amazon.de/gp/pdp/taf/3813506479%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3813506479</URL>
            </ItemLink>
            <ItemLink>
                <Description>All Customer Reviews</Description>
                <URL>http://www.amazon.de/review/product/3813506479%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3813506479</URL>
            </ItemLink>
            <ItemLink>
                <Description>All Offers</Description>
                <URL>http://www.amazon.de/gp/offer-listing/3813506479%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3813506479</URL>
            </ItemLink>
        </ItemLinks>
        <ItemAttributes>
            <Author>Dörte Hansen</Author>
            <Binding>Gebundene Ausgabe</Binding>
            <EAN>9783813506471</EAN>
            <EANList>
                <EANListElement>9783813506471</EANListElement>
            </EANList>
            <ISBN>3813506479</ISBN>
            <IsEligibleForTradeIn>1</IsEligibleForTradeIn>
            <ItemDimensions>
                <Height Units="hundredths-inches">870</Height>
                <Length Units="hundredths-inches">567</Length>
                <Width Units="hundredths-inches">114</Width>
            </ItemDimensions>
            <Label>Albrecht Knaus Verlag</Label>
            <Languages>
                <Language>
                    <Name>Deutsch</Name>
                    <Type>Published</Type>
                </Language>
                <Language>
                    <Name>Deutsch</Name>
                    <Type>Original</Type>
                </Language>
            </Languages>
            <ListPrice>
                <Amount>1999</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 19,99</FormattedPrice>
            </ListPrice>
            <Manufacturer>Albrecht Knaus Verlag</Manufacturer>
            <NumberOfPages>288</NumberOfPages>
            <PackageDimensions>
                <Height Units="hundredths-inches">118</Height>
                <Length Units="hundredths-inches">858</Length>
                <Weight Units="hundredths-pounds">101</Weight>
                <Width Units="hundredths-inches">559</Width>
            </PackageDimensions>
            <ProductGroup>Book</ProductGroup>
            <ProductTypeName>ABIS_BOOK</ProductTypeName>
            <PublicationDate>2015-02-16</PublicationDate>
            <Publisher>Albrecht Knaus Verlag</Publisher>
            <Studio>Albrecht Knaus Verlag</Studio>
            <Title>Altes Land: Roman</Title>
            <TradeInValue>
                <Amount>965</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 9,65</FormattedPrice>
            </TradeInValue>
        </ItemAttributes>
        <OfferSummary>
            <LowestNewPrice>
                <Amount>1999</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 19,99</FormattedPrice>
            </LowestNewPrice>
            <LowestUsedPrice>
                <Amount>1599</Amount>
                <CurrencyCode>EUR</CurrencyCode>
                <FormattedPrice>EUR 15,99</FormattedPrice>
            </LowestUsedPrice>
            <TotalNew>72</TotalNew>
            <TotalUsed>8</TotalUsed>
            <TotalCollectible>0</TotalCollectible>
            <TotalRefurbished>0</TotalRefurbished>
        </OfferSummary>
        <Offers>
            <TotalOffers>1</TotalOffers>
            <TotalOfferPages>1</TotalOfferPages>
            <MoreOffersUrl>http://www.amazon.de/gp/offer-listing/3813506479%3FSubscriptionId%3DAKIAI554OLCUMRCYB7ZA%26tag%3DjPp08vuSO4osfgfbCbEdF7TNqnWOm7YtprtqRPB9%26linkCode%3Dxm2%26camp%3D2025%26creative%3D12738%26creativeASIN%3D3813506479</MoreOffersUrl>
            <Offer>
                <OfferAttributes>
                    <Condition>New</Condition>
                </OfferAttributes>
                <OfferListing>
                    <OfferListingId>aeRv5KPt26T8S0hLrgV8Bv9UPYABYOMijGRxffbNJXUZSN4XfeeOZZpCZ28EURzmgMLlcYEBSRlMXS%2F8Z0pN1JbYerndME%2B2VK3RosfdQJA%3D</OfferListingId>
                    <Price>
                        <Amount>1999</Amount>
                        <CurrencyCode>EUR</CurrencyCode>
                        <FormattedPrice>EUR 19,99</FormattedPrice>
                    </Price>
                    <Availability>Gewöhnlich versandfertig in 24 Stunden</Availability>
                    <AvailabilityAttributes>
                        <AvailabilityType>now</AvailabilityType>
                        <MinimumHours>0</MinimumHours>
                        <MaximumHours>0</MaximumHours>
                    </AvailabilityAttributes>
                    <IsEligibleForSuperSaverShipping>1</IsEligibleForSuperSaverShipping>
                </OfferListing>
            </Offer>
        </Offers>
    </Item>
</Items>

我想获取任何 ASIN 元素。所以我尝试了这个：

from lxml import etree
doc = etree.fromstring(xmlstring)
items = doc.xpath('//Items/Item')
for a in items:
    asin = a.xpath('//ASIN/text()')
    print asin

我得到的是这样的：

['3570102769', '3813506479']
['3570102769', '3813506479']

但我想要这个：

['3570102769']
['3813506479']

我不明白这里有什么问题？我想我应该遍历任何元素，并且在每个元素中都是 one item with one asin。为什么它 return two 次 two asin?

Answer 1

当您搜索 a.xpath('//ASIN/text()') 时，您正在再次搜索完整的文档树。引用自 XML Path language specification:

//para selects all the para descendants of the document root and thus selects all para elements in the same document as the context node

所以你正在做的是遍历匹配的 Item 节点并说 "Give me all ASIN nodes in this document please"。此（Item 节点）的上下文被忽略。

您应该做的是直接 select ASIN 子节点。按照您的原始实现，这可能如下所示：

doc = etree.fromstring(xmlstring)
items = doc.xpath('//Items/Item')
for a in items:
    asin = a.xpath('ASIN/text()')
    print asin

它给出了你想要的输出：

['3570102769']
['3813506479']

或者，如果您不确定 Item 节点中您的 ASIN 出现的位置，您可以使用 .//ASIN/text()

如何在 Python 中解析此 XML 响应？

How to parse this XML response in Python?

python

xml

xpath

parsing

lxml