使用 RCurl 的 POST 请求
作为探索如何在 R 中为 Denver RUG 制作包的一种方式，我认为围绕 datasciencetoolkit API 编写 R 包装器将是一个有趣的小项目。如您所想，基本的 R 工具来自 RCurl 包。我陷入了一个看似简单的问题，我希望这个论坛中的某人能够为我指出正确的方向。基本问题是我似乎无法使用 postForm() 将未键入的字符串作为curl 中数据选项的一部分传递，即curl -d "string" "address_to_api"。
例如，从命令行我可能会
$ curl -d "Tim O'Reilly, Archbishop Huxley" "http://www.datasciencetoolkit.org/text2people"
成功。然而，当将附加参数传递到 POST 请求时，postForm() 似乎需要一个显式的键。我已经浏览了 datasciencetoolkit 代码和开发人员文档以寻找可能的密钥，但似乎找不到任何东西。
顺便说一句，通过 GET 请求将输入传递到 DSTK API 的其他部分非常简单。例如，
ip2coordinates <- function(ip) {
api <- "http://www.datasciencetoolkit.org/ip2coordinates/"
result <- getURL(paste(api, URLencode(ip), sep=""))
names(result) <- "ip"
return(result)
}
ip2coordinates('67.169.73.113')
将产生所需的结果。
需要明确的是，我已经阅读了 DTL omegahat 站点上的 RCurl 文档、包中的 RCurl 文档以及curl 手册页。然而，我错过了一些关于curl的基本知识（或者可能是postForm()函数中的.opts()），而且我似乎无法理解它。
在 python 中，我基本上可以使用 httplib.HTTPConnection 发出“原始”POST 请求——R 中有类似的东西吗？我也查看了 httpRequest 包中的 simplePostToHost 函数，它似乎锁定了我的 R 会话（它似乎也需要密钥）。
FWIW，我在 Mac 10.6.7 上使用 R 2.13.0。
非常感谢任何帮助。如果您有兴趣使用数据科学工具包，所有代码很快就会在 github 上提供。
干杯。
As a way of exploring how to make a package in R for the Denver RUG, I decided that it would be a fun little project to write an R wrapper around the datasciencetoolkit API. The basic R tools come from the RCurl package as you might imagine. I am stuck on a seemingly simple problem and I'm hoping that somebody in this forum might be able to point me in the right direction. The basic problem is that I can't seem to use postForm() to pass an un-keyed string as part of the data option in curl, i.e. curl -d "string" "address_to_api".
For example, from the command line I might do
$ curl -d "Tim O'Reilly, Archbishop Huxley" "http://www.datasciencetoolkit.org/text2people"
with success. However, it seems that postForm() requires an explicit key when passing additional arguments into the POST request. I've looked through the datasciencetoolkit code and developer docs for a possible key, but can't seem to find anything.
As an aside, it's pretty straightforward to pass inputs via a GET request to other parts of the DSTK API. For example,
ip2coordinates <- function(ip) {
api <- "http://www.datasciencetoolkit.org/ip2coordinates/"
result <- getURL(paste(api, URLencode(ip), sep=""))
names(result) <- "ip"
return(result)
}
ip2coordinates('67.169.73.113')
will produce the desired results.
To be clear, I've read through the RCurl docs on DTL's omegahat site, the RCurl docs with the package, and the curl man page. However, I'm missing something fundamental with respect to curl (or perhaps .opts() in the postForm() function) and I can't seem to get it.
In python, I could basically make a 'raw' POST request using httplib.HTTPConnection -- is something like that available in R? I've looked at the simplePostToHost function in the httpRequest package as well and it just seemed to lock my R session (it seems to require a key as well).
FWIW, I'm using R 2.13.0 on Mac 10.6.7.
Any help is much appreciated. All of the code will soon be available on github if you're interested in playing around with the data science toolkit.
Cheers.
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对于 httr，这只是：
With httr, this is just:
一般来说，在您尝试发布未键入的内容的情况下，您只需为该值分配一个虚拟密钥即可。例如：
如果我使用 b="Archbishop Huxley" 等，效果会相同。
享受 RCurl - 这可能是我最喜欢的 R 包。如果您喜欢冒险，升级到 ~ libcurl 7.21 会通过curl 公开一些新方法（包括 SMTP 等）。
Generally, in those cases where you're trying to POST something that isn't keyed, you can just assign a dummy key to that value. For example:
Would work the same if I'd used b="Archbishop Huxley", etc.
Enjoy RCurl - it's probably my favorite R package. If you get adventurous, upgrading to ~ libcurl 7.21 exposes some new methods via curl (including SMTP, etc.).
来自 R 帮助列表上的 Duncan Temple Lang：
postForm() 使用与curl -d 命令不同的样式（或具体的内容类型）提交表单。
切换 style = 'POST' 使用相同的类型，但快速猜测，参数名称 'a' 导致混乱
结果是空的 JSON 数组 - “[]”。
一个快速的解决方法是直接使用curlPerform()而不是postForm()，
这样
你就可以使用fromJSON()将其转换为R中的数据。
From Duncan Temple Lang on the R-help list:
postForm() is using a different style (or specifically Content-Type) of submitting the form than the curl -d command.
Switching the style = 'POST' uses the same type, but at a quick guess, the parameter name 'a' is causing confusion
and the result is the empty JSON array - "[]".
A quick workaround is to use curlPerform() directly rather than postForm()
This yields
and you can use fromJSON() to transform it into data in R.
我只是想指出，通过 postForm 函数传递原始字符串肯定存在问题。例如，如果我从命令行使用curl，我会得到以下结果：
并且在 RI get
请注意，它返回 JSON 字符串中的两个元素，并且没有一个与 start_index 或 end_index 匹配。这是编码问题还是什么问题？
I just wanted to point out that there must be an issue with passing a raw string via the postForm function. For example, if I use curl from the command line, I get the following:
and in R I get
Note that it returns two elements in the JSON string and neither one matches on the start_index or end_index. Is this a problem with encoding or something?
httpRequest 包中的 simplePostToHost 函数可能会满足您在此处的需求。
The simplePostToHost function in the httpRequest package might do what you are looking for here.