我有以下XML文档：
<files>
<elements xsi:type="foo:elementType1">
<name>foo1</name>
</elements>
<elements xsi:type="foo:elementType1">
<name>foo2</name>
<other>
<elements>
<data1>data1</data1>
<data2>data2</data2>
</elements>
</other>
</elements>
<elements>
<name>foo3</name>
<affiliates>
<elements xsi:type="foo:elementType1">
<name>foo4</name>
</elements>
</affiliates>
</elements>
</files>
我只需要抓取type = "foo:elementType1"的元素。我尝试了这个，但是我得到了空洞的结果。
elems = doc.search("//elements[@type='foo:elementType1']")
我错过了什么？
答案 0 :(得分：19)
我从不使用xpath语法，因为它对我来说从来都不是直观的，但使用css选择器接口应该可行：
elems = doc.search 'elements[type="foo:elementType1"]'
答案 1 :(得分：5)
修改 使用OP提供的XML的精简（SO字符约束）副本，使用Nokogiri v1.5.0可以正常工作：
require 'nokogiri'
xml = <<XML
<files>
<elements>
<loginForm xsi:type="ns5:Form" xmlns:ns5="http://common.soap.yodlee.com">
<conjunctionOp>AND</conjunctionOp>
<componentList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN2</name>
<displayName>Answer 1</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN2</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>LOGIN</name>
<displayName>Account #</displayName>
<isEditable>true</isEditable>
<isOptional>false</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>LOGIN</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>PASSWORD</name>
<displayName>PIN</displayName>
<isEditable>true</isEditable>
<isOptional>false</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>PASSWORD</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>PASSWORD</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoChoice">
<fieldInfoList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_OPTIONS1</name>
<displayName>Question 1</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<validValues>
<elements>first three digits of your Social Security</elements>
<elements>last four digits of your Social Security</elements>
<elements>your favorite food</elements>
<elements>your favorite sport</elements>
<elements>your mother's maiden name</elements>
<elements>your pet's name</elements>
<elements>What was your first car</elements>
<elements>your school mascot</elements>
<elements>When did you graduate from school</elements>
<elements>Where did you grow up</elements>
<elements>Where do you work</elements>
<elements>Where were you born</elements>
<elements>Who is your hero</elements>
</validValues>
<displayValidValues>
<elements>What are the first three digits of your Social Security?</elements>
<elements>What are the last four digits of your Social Security?</elements>
<elements>What is your favorite food?</elements>
<elements>What is your favorite sport?</elements>
<elements>What is your mother's maiden name?</elements>
<elements>What is your pet's name?</elements>
<elements>What was your first car?</elements>
<elements>What was your school mascot?</elements>
<elements>When did you graduate from school?</elements>
<elements>Where did you grow up?</elements>
<elements>Where do you work?</elements>
<elements>Where were you born?</elements>
<elements>Who is your hero?</elements>
</displayValidValues>
<valueIdentifier>OP_OPTIONS1</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>OPTIONS</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN1</name>
<displayName>Custom Question 1</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN1</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</fieldInfoList>
</elements>
<elements xsi:type="ns5:FieldInfoChoice">
<fieldInfoList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_OPTIONS2</name>
<displayName>Question 2</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<validValues>
<elements>first three digits of your Social Security</elements>
<elements>last four digits of your Social Security</elements>
<elements>your favorite food</elements>
<elements>your favorite sport</elements>
<elements>your mother's maiden name</elements>
<elements>your pet's name</elements>
<elements>What was your first car</elements>
<elements>your school mascot</elements>
<elements>When did you graduate from school</elements>
<elements>Where did you grow up</elements>
<elements>Where do you work</elements>
<elements>Where were you born</elements>
<elements>Who is your hero</elements>
</validValues>
<displayValidValues>
<elements>What are the first three digits of your Social Security?</elements>
<elements>What are the last four digits of your Social Security?</elements>
<elements>What is your favorite food?</elements>
<elements>What is your favorite sport?</elements>
<elements>What is your mother's maiden name?</elements>
<elements>What is your pet's name?</elements>
<elements>What was your first car?</elements>
<elements>What was your school mascot?</elements>
<elements>When did you graduate from school?</elements>
<elements>Where did you grow up?</elements>
<elements>Where do you work?</elements>
<elements>Where were you born?</elements>
<elements>Who is your hero?</elements>
</displayValidValues>
<valueIdentifier>OP_OPTIONS2</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>OPTIONS</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN3</name>
<displayName>Custom Question 2</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN3</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</fieldInfoList>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN4</name>
<displayName>Answer 2</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN4</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoChoice">
<fieldInfoList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_OPTIONS3</name>
<displayName>Question 3</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<validValues>
<elements>first three digits of your Social Security</elements>
<elements>last four digits of your Social Security</elements>
<elements>your favorite food</elements>
<elements>your favorite sport</elements>
<elements>your mother's maiden name</elements>
<elements>your pet's name</elements>
<elements>What was your first car</elements>
<elements>your school mascot</elements>
<elements>When did you graduate from school</elements>
<elements>Where did you grow up</elements>
<elements>Where do you work</elements>
<elements>Where were you born</elements>
<elements>Who is your hero</elements>
</validValues>
<displayValidValues>
<elements>What are the first three digits of your Social Security?</elements>
<elements>What are the last four digits of your Social Security?</elements>
<elements>What is your favorite food?</elements>
<elements>What is your favorite sport?</elements>
<elements>What is your mother's maiden name?</elements>
<elements>What is your pet's name?</elements>
<elements>What was your first car?</elements>
<elements>What was your school mascot?</elements>
<elements>When did you graduate from school?</elements>
<elements>Where did you grow up?</elements>
<elements>Where do you work?</elements>
<elements>Where were you born?</elements>
<elements>Who is your hero?</elements>
</displayValidValues>
<valueIdentifier>OP_OPTIONS3</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>OPTIONS</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN5</name>
<displayName>Custom Question 3</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN5</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</fieldInfoList>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN6</name>
<displayName>Answer 3</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN6</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoChoice">
<fieldInfoList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_OPTIONS4</name>
<displayName>Question 4</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<validValues>
<elements>first three digits of your Social Security</elements>
<elements>last four digits of your Social Security</elements>
<elements>your favorite food</elements>
<elements>your favorite sport</elements>
<elements>your mother's maiden name</elements>
<elements>your pet's name</elements>
<elements>What was your first car</elements>
<elements>your school mascot</elements>
<elements>When did you graduate from school</elements>
<elements>Where did you grow up</elements>
<elements>Where do you work</elements>
<elements>Where were you born</elements>
<elements>Who is your hero</elements>
</validValues>
<displayValidValues>
<elements>What are the first three digits of your Social Security?</elements>
<elements>What are the last four digits of your Social Security?</elements>
<elements>What is your favorite food?</elements>
<elements>What is your favorite sport?</elements>
<elements>What is your mother's maiden name?</elements>
<elements>What is your pet's name?</elements>
<elements>What was your first car?</elements>
<elements>What was your school mascot?</elements>
<elements>When did you graduate from school?</elements>
<elements>Where did you grow up?</elements>
<elements>Where do you work?</elements>
<elements>Where were you born?</elements>
<elements>Who is your hero?</elements>
</displayValidValues>
<valueIdentifier>OP_OPTIONS4</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>OPTIONS</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN7</name>
<displayName>Custom Question 4</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN7</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</fieldInfoList>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN8</name>
<displayName>Answer 4</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN8</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoChoice">
<fieldInfoList>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_OPTIONS5</name>
<displayName>Question 5</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<validValues>
<elements>first three digits of your Social Security</elements>
<elements>last four digits of your Social Security</elements>
<elements>your favorite food</elements>
<elements>your favorite sport</elements>
<elements>your mother's maiden name</elements>
<elements>your pet's name</elements>
<elements>What was your first car</elements>
<elements>your school mascot</elements>
<elements>When did you graduate from school</elements>
<elements>Where did you grow up</elements>
<elements>Where do you work</elements>
<elements>Where were you born</elements>
<elements>Who is your hero</elements>
</validValues>
<displayValidValues>
<elements>What are the first three digits of your Social Security?</elements>
<elements>What are the last four digits of your Social Security?</elements>
<elements>What is your favorite food?</elements>
<elements>What is your favorite sport?</elements>
<elements>What is your mother's maiden name?</elements>
<elements>What is your pet's name?</elements>
<elements>What was your first car?</elements>
<elements>What was your school mascot?</elements>
<elements>When did you graduate from school?</elements>
<elements>Where did you grow up?</elements>
<elements>Where do you work?</elements>
<elements>Where were you born?</elements>
<elements>Who is your hero?</elements>
</displayValidValues>
<valueIdentifier>OP_OPTIONS5</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>OPTIONS</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN9</name>
<displayName>Custom Question 5</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN9</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</fieldInfoList>
</elements>
<elements xsi:type="ns5:FieldInfoSingle">
<name>OP_LOGIN10</name>
<displayName>Answer 5</displayName>
<isEditable>true</isEditable>
<isOptional>true</isOptional>
<isEscaped>false</isEscaped>
<isOptionalMFA>false</isOptionalMFA>
<isMFA>false</isMFA>
<valueIdentifier>OP_LOGIN10</valueIdentifier>
<valueMask>LOGIN_FIELD</valueMask>
<fieldType>TEXT</fieldType>
<size>20</size>
<maxlength>40</maxlength>
<fieldErrorCode xsi:nil="1"/>
</elements>
</componentList>
</loginForm>
</elements>
</files>
XML
doc = Nokogiri::XML(xml)
doc.xpath("//elements[@type='ns5:FieldInfoSingle']").each do |element|
puts element.xpath("name").text
end