如何使用R将XML请求发送到API

Question

我试图从这个政府网站的API自动下载一些数据.

网站指示:

All requests for this version should be made to the following URL:
http://api.finder.healthcare.gov/v2.0/

我可以找到大量的相关信息如何发送XML请求,但没有一个例子是R特异性..并有大量的R代码里面,在那里,展示了如何使用XML,httr以及RCurl包,但我找不到任何的例子在SO或r-help邮件列表中,了解如何实际发送 xml请求...还有更多用于解析响应的文档.

在政府网站上,如果单击该PlansForIndividualOrFamily Samples示例,则会显示需要发送的xml请求(下面的代码).

url <- "http://api.finder.healthcare.gov/v2.0/"

xml.request <-
    "<?xml version='1.0' encoding='UTF-8'?>
    <PrivateOptionsAPIRequest>
        <PlansForIndividualOrFamilyRequest>
            <Enrollees>
                <Primary>
                    <DateOfBirth>1990-01-01</DateOfBirth>
                    <Gender>Male</Gender>
                    <TobaccoUser>Smoker</TobaccoUser>
                </Primary>
            </Enrollees>
            <Location>
                <ZipCode>69201</ZipCode>
                <County>
                    <CountyName>CHERRY</CountyName>
                    <StateCode>NE</StateCode>
                </County>
            </Location>
            <InsuranceEffectiveDate>2012-10-01</InsuranceEffectiveDate>
        <IsFilterAnalysisRequiredIndicator>false</IsFilterAnalysisRequiredIndicator>
        <PaginationInformation>
            <PageNumber>1</PageNumber>
            <PageSize>10</PageSize>
        </PaginationInformation>
        <SortOrder>
            <SortField>OOP LIMIT - INDIVIDUAL - IN NETWORK</SortField>
            <SortDirection>ASC</SortDirection>
        </SortOrder>
        <Filter/>
        </PlansForIndividualOrFamilyRequest>
    </PrivateOptionsAPIRequest>"

Answer 1

用RCurl你这样做;

myheader=c(Connection="close", 
            'Content-Type' = "application/xml",
             'Content-length' =nchar(xml.request))
data =  getURL(url = url,
                    postfields=xml.request,
                    httpheader=myheader,
                    verbose=TRUE)

就是这样.然后您可以使用xpathApplyXML包来检索数据.例如,要获得家庭ID:

library(XML)
xmltext  <- xmlTreeParse(data, asText = TRUE,useInternalNodes=T)
 unlist(xpathApply(xmltext,'//Plan/PlanID',xmlValue))  ## change the right xpath here

 "29678NE0780012" "29678NE0780011" "29678NE0140010"  
  "29678NE0780010" "29678NE0140019" "29678NE0140018" "29678NE0140017"
  "29678NE0140016" "29678NE0780005" "29678NE0780004"