设计

R作为后端。我使用plumber包公开API。

NodeJS和ExpressJS应用程序。express检查路由器，然后请求适当的API从R获取数据。

代码

r:

#* @get /reportTypes
#* function to listen to the request and return the results from the csv file. 
#* If the file doesn't exists, it returns an 404 error.
#* @serializer unboxedJSON

function(res, req){
  
  filename <- "file-does-not-exist.csv"
  
  if(file.exists(filename)){
  
      reportTypes <- read.csv(filename)
   
      return(reportTypes) 
  }
  else{
    res$status <- 404
    stop("List of report types could not be loaded.")
  }
  
} 

r错误:

<simpleError in (function (res, req) {    filename <- "ReportTypes1.csv"    if (file.exists(filename)) {        reportTypes <- read.csv(filename)        return(reportTypes)    }    else {        stop("List of report types could not be loaded.")    }})(res = <environment>, req = <environment>): List of report types could not be loaded.>

ExpressJS:

在这里，路由器请求来自给定URL的响应。它确实从plumber接收到错误消息，但我不明白为什么请求会以状态200传递给客户机，而客户机却没有将该错误解释为错误。它将解释为有效的响应。

router.get('/', function (req, res) {

  request.get({ url: 'http://localhost:5762/reportTypes' },
    function (error, response, body) {
      if (!error && response.statusCode == 200) {
        res.send(body);
      }
      else {
        console.log("Error: ", error);
        console.log("body: ", body);
        res.send(body);
      }
    });

});

在repressjs中，错误没有从r解释为错误，这是我做错了什么？