使用R中的参数构建URL

Question

使用R中的参数构建请求URL的最佳方法是什么？到目前为止,我想出了这个:

library(magrittr)   
library(httr)
library(data.table)
url <- list(hostname = "geo.stat.fi/geoserver/vaestoalue/wfs",
            scheme = "https",
            query = list(service = "WFS",
                         version = "2.0.0",
                         request = "GetFeature",
                         typename = "vaestoalue:kunta_vaki2017",
                         outputFormat = "application/json")) %>% 
       setattr("class","url")
request <- build_url(url)

我喜欢我现在的代码是,我可以轻松更改参数值并重建URL.

此外,生成的url正确地进行了html编码:

https://geo.stat.fi/geoserver/vaestoalue/wfs/?service=WFS&version=2.0.0&request=GetFeature&typename=vaestoalue%3Akunta_vaki2017&outputFormat=application%2Fjson

但是加载data.table库,只是为了构建一个url,感觉不对.这样做有好处吗？

Answer 1

您绝对不需要data.table构建 URL。正如 Jos\xc3\xa9 所指出的，它被加载为使用一个方便的函数，你可以用它来模仿：

\n\n

set_class <- function(o, v) { class(o) <- v ; invisible(o) }\n

\n\n

另外，除非目标是拥有 URL 而只是从站点读取数据，否则您也可以只使用httr动词：

\n\n

httr::GET(\n  url = "https://geo.stat.fi/geoserver/vaestoalue/wfs",\n  query = list(\n    service = "WFS",\n    version = "2.0.0",\n    request = "GetFeature",\n    typename = "vaestoalue:kunta_vaki2017",\n    outputFormat = "application/json"\n  )\n) -> res\n\n\ndat <- httr::content(res)\n\nstr(dat, 1)\n## List of 5\n##  $ type         : chr "FeatureCollection"\n##  $ totalFeatures: int 311\n##  $ features     :List of 311\n##  $ crs          :List of 2\n##  $ bbox         :List of 4\n

\n