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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, callback)

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

Options

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: 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([1, 2, 3]).map(function(i) {
    return r.http('http://httpbin.org/get', { params: { user: i } });
}).run(conn, callback)

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

r.table('data').map(function(row) {
    return r.http('http://httpbin.org/put', { method: 'PUT', data: row });
}).run(conn, callback)

Example: Perform a POST request with accompanying data.

Using form-encoded data:

r.http('http://httpbin.org/post',
       { method: 'POST', data: { player: 'Bob', game: 'tic tac toe' } })
.run(conn, callback)

Using JSON data:

r.http('http://httpbin.org/post',
       { method: 'POST',
         data: r.expr(value).coerceTo('string'),
         header: { 'Content-Type': 'application/json' } })
.run(conn, callback)

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 optional arguments page and pageLimit. 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.
  • pageLimit: 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 function(info) { return info('header')('link')('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",
       { page: 'link-next', pageLimit: 3 }
).run(conn, callback)

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 HTTP 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',
       { page: function(info) { return info('body')('meta')('next').default(null); },
         pageLimit: 5 })
.run(conn, callback)

Learn more

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

Get more help

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