ReQL command: http

Command syntax

r.http(url[, options]) → value
r.http(url[, options]) → stream

Description

Retrieve data from the specified URL over HTTP. The return type depends on the resultFormat option, which checks the Content-Type of the response by default.

Example: Perform an HTTP GET and store the result in a table.

r.table("posts").insert(r.http("http://httpbin.org/get")).run(conn);

See the tutorial on r.http for more examples on how to use this command.

Options

These options are specified with the optArg command.

General Options

• timeout: timeout period in seconds to wait before aborting the connect (default 30).
• attempts: number of retry attempts to make after failed connections (default 5).
• redirects: number of redirect and location headers to follow (default 1).
• verify: if true, verify the server’s SSL certificate (default true).
• resultFormat: string specifying the format to return results in. One of the following:
  • text: always return a string.
  • json: parse the result as JSON, raising an error on failure.
  • jsonp: parse the result as Padded JSON.
  • binary: return a binary object.
  • auto: parse the result based on its Content-Type (the default):
    • application/json: as json
    • application/json-p, text/json-p, text/javascript: as jsonp
    • audio/*, video/*, image/*, application/octet-stream: as binary
    • anything else: as text

Request Options

• method: HTTP method to use for the request. One of GET, POST, PUT, PATCH, DELETE or HEAD. Default: GET.
• auth: object giving authentication, with the following fields:
  • type: basic (default) or digest
  • user: username
  • pass: password in plain text
• params: hashMap or object specifying URL parameters to append to the URL as encoded key/value pairs. { "query": "banana", "limit": 2 } will be appended as ?query=banana&limit=2. Default: no parameters.
• header: Extra header lines to include. The value may be an array of strings or an object. Default: Accept-Encoding: deflate;q=1, gzip;q=0.5 and User-Agent: RethinkDB/<VERSION>.
• data: Data to send to the server on a POST, PUT, PATCH, or DELETE request. For POST requests, data may be either an object (which will be written to the body as form-encoded key/value pairs) or a string; for all other requests, data will be serialized as JSON and placed in the request body, sent as Content-Type: application/json. Default: no data will be sent.

Example: Perform multiple requests with different parameters.

r.expr(r.array(1, 2, 3)).map(
    i -> r.http("http://httpbin.org/get")
          .optArg("params", r.hashMap("user", i))
).run(conn);

Example: Perform a PUT request for each item in a table.

r.table("data").map(
    row -> r.http("http://httpbin.org/put")
            .optArg("method", "PUT")
            .optArg("data", row)
).run(conn);

Example: Perform a POST request with accompanying data.

Using form-encoded data:

r.http("http://httpbin.org/post").optArg("method", "POST")
 .optArg("data", r.hashMap("player", "Bob").with("game", "tic tac toe"))
 .run(conn);

Using JSON data:

r.http("http://httpbin.org/post").optArg("method", "POST")
 .optArg("data", r.expr(value).coerceTo("string"))
 .optArg("header", r.hashMap("Content-Type", "application/json"))
 .run(conn);

Pagination

r.http supports depagination, which will request multiple pages in a row and aggregate the results into a stream. The use of this feature is controlled by the optArgs page and page_limit. Either none or both of these arguments must be provided.

• page: This option may specify either a built-in pagination strategy (see below), or a function to provide the next URL and/or params to request.
• page_limit: An integer specifying the maximum number of requests to issue using the page functionality. This is to prevent overuse of API quotas, and must be specified with page.
  • -1: no limit
  • 0: no requests will be made, an empty stream will be returned
  • n: n requests will be made

At the moment, the only built-in strategy is link-next, which is equivalent to info -> info.g("header").g("link").g("rel='next'").default_(null).

Example: Perform a GitHub search and collect up to 3 pages of results.

r.http("https://api.github.com/search/code?q=addClass+user:mozilla")
 .optArg("page", "link-next").optArg("page_limit", 3)
 .run(conn);

As a function, page takes one parameter, an object of the format:

{
    "params": object,  // the URL parameters used in the last request
    "header": object,  // the headers of the last response as key/value pairs
    "body": value      // the body of the last response in the format
}                      //   specified by `resultFormat`

The header field will be a parsed version of the header with fields lowercased, like so:

{
    "content-length": "1024",
    "content-type": "application/json",
    "date": "Thu, 1 Jan 1970 00:00:00 GMT",
    "link": {
        "rel=\"last\"": "http://example.com/?page=34",
        "rel=\"next\"": "http://example.com/?page=2"
    }
}

The page function may return a string corresponding to the next URL to request, null indicating that there is no more to get, or an object of the format:

{
    "url": string,    // the next URL to request, or null for no more pages
    "params": object  // new URL parameters to use, will be merged with the
}                     //   previous request's params

Example: Perform depagination with a custom page function.

r.http("example.com/pages")
 .optArg("page", info -> info.g("body").g("meta").g("next").default_(null))
 .optArg("page_limit", 5)
 .run(conn);

Learn more

See the tutorial on r.http for more examples on how to use this command.