httpclient

This module implements a simple HTTP client that can be used to retrieve webpages and other data.

Retrieving a website

This example uses HTTP GET to retrieve http://google.com:

import httpClient
var client = newHttpClient()
echo client.getContent("http://google.com")

The same action can also be performed asynchronously, simply use the AsyncHttpClient:

import httpClient
var client = newAsyncHttpClient()
echo await client.getContent("http://google.com")

The functionality implemented by HttpClient and AsyncHttpClient is the same, so you can use whichever one suits you best in the examples shown here.

Note: You will need to run asynchronous examples in an async proc otherwise you will get an Undeclared identifier: 'await' error.

Using HTTP POST

This example demonstrates the usage of the W3 HTML Validator, it uses multipart/form-data as the Content-Type to send the HTML to be validated to the server.

var client = newHttpClient()
var data = newMultipartData()
data["output"] = "soap12"
data["uploaded_file"] = ("test.html", "text/html",
  "<html><head></head><body><p>test</p></body></html>")

echo client.postContent("http://validator.w3.org/check", multipart=data)

You can also make post requests with custom headers. This example sets Content-Type to application/json and uses a json object for the body

import httpclient, json

let client = newHttpClient()
client.headers = newHttpHeaders({ "Content-Type": "application/json" })
let body = %*{
    "data": "some text"
}
let response = client.request("http://some.api", httpMethod = HttpPost, body = $body)
echo response.status

Progress reporting

You may specify a callback procedure to be called during an HTTP request. This callback will be executed every second with information about the progress of the HTTP request.

import asyncdispatch, httpclient

proc onProgressChanged(total, progress, speed: BiggestInt) {.async.} =
  echo("Downloaded ", progress, " of ", total)
  echo("Current rate: ", speed div 1000, "kb/s")

proc asyncProc() {.async.} =
  var client = newAsyncHttpClient()
  client.onProgressChanged = onProgressChanged
  discard await client.getContent("http://speedtest-ams2.digitalocean.com/100mb.test")

waitFor asyncProc()

If you would like to remove the callback simply set it to nil.

client.onProgressChanged = nil

Warning: The total reported by httpclient may be 0 in some cases.

SSL/TLS support

This requires the OpenSSL library, fortunately it's widely used and installed on many operating systems. httpclient will use SSL automatically if you give any of the functions a url with the https schema, for example: https://github.com/.

You will also have to compile with ssl defined like so: nim c -d:ssl ....

Timeouts

Currently only the synchronous functions support a timeout. The timeout is measured in milliseconds, once it is set any call on a socket which may block will be susceptible to this timeout.

It may be surprising but the function as a whole can take longer than the specified timeout, only individual internal calls on the socket are affected. In practice this means that as long as the server is sending data an exception will not be raised, if however data does not reach the client within the specified timeout a TimeoutError exception will be raised.

Here is how to set a timeout when creating an HttpClient instance:

import httpclient

let client = newHttpClient(timeout = 42)

Proxy

A proxy can be specified as a param to any of the procedures defined in this module. To do this, use the newProxy constructor. Unfortunately, only basic authentication is supported at the moment.

Some examples on how to configure a Proxy for HttpClient:

import httpclient

let myProxy = newProxy("http://myproxy.network")
let client = newHttpClient(proxy = myProxy)

Get Proxy URL from environment variables:

import httpclient

var url = ""
try:
  if existsEnv("http_proxy"):
    url = getEnv("http_proxy")
  elif existsEnv("https_proxy"):
    url = getEnv("https_proxy")
except ValueError:
  echo "Unable to parse proxy from environment variables."

let myProxy = newProxy(url = url)
let client = newHttpClient(proxy = myProxy)

Redirects

The maximum redirects can be set with the maxRedirects of int type, it specifies the maximum amount of redirects to follow, it defaults to 5, you can set it to 0 to disable redirects.

Here you can see an example about how to set the maxRedirects of HttpClient:

import httpclient

let client = newHttpClient(maxRedirects = 0)

Types

Response = ref object
  version*: string
  status*: string
  headers*: HttpHeaders
  body: string
  bodyStream*: Stream
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AsyncResponse = ref object
  version*: string
  status*: string
  headers*: HttpHeaders
  body: string
  bodyStream*: FutureStream[string]
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Proxy = ref object
  url*: Uri
  auth*: string
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MultipartEntries = openArray[tuple[name, content: string]]
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MultipartData = ref object
  content: seq[string]
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ProtocolError = object of IOError
exception that is raised when server does not conform to the implemented protocol   Source Edit
HttpRequestError = object of IOError
Thrown in the getContent proc and postContent proc, when the server returns an error   Source Edit
ProgressChangedProc[ReturnType] = proc (total, progress, speed: BiggestInt): ReturnType {...}{.
    closure, gcsafe.}
  Source Edit
HttpClientBase[SocketType] = ref object
  socket: SocketType
  connected: bool
  currentURL: Uri              ## Where we are currently connected.
  headers*: HttpHeaders        ## Headers to send in requests.
  maxRedirects: int
  userAgent: string
  timeout*: int                ## Only used for blocking HttpClient for now.
  proxy: Proxy                 ## ``nil`` or the callback to call when request progress changes.
  when SocketType is Socket:
    onProgressChanged
  else:
    onProgressChanged
  when false:
    sslContext
  contentTotal: BiggestInt
  contentProgress: BiggestInt
  oneSecondProgress: BiggestInt
  lastProgressReport: MonoTime
  when SocketType is AsyncSocket:
      bodyStream
      parseBodyFut

  else:
    bodyStream
  getBody: bool                ## When `false`, the body is never read in requestAux.
  
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HttpClient = HttpClientBase[Socket]
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AsyncHttpClient = HttpClientBase[AsyncSocket]
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Consts

defUserAgent = "Nim httpclient/0.20.99"
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Procs

proc code(response: Response | AsyncResponse): HttpCode {...}{.
    raises: [ValueError, OverflowError].}

Retrieves the specified response's HttpCode.

Raises a ValueError if the response's status does not have a corresponding HttpCode.

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proc contentType(response: Response | AsyncResponse): string

Retrieves the specified response's content type.

This is effectively the value of the "Content-Type" header.

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proc contentLength(response: Response | AsyncResponse): int

Retrieves the specified response's content length.

This is effectively the value of the "Content-Length" header.

A ValueError exception will be raised if the value is not an integer.

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proc lastModified(response: Response | AsyncResponse): DateTime

Retrieves the specified response's last modified time.

This is effectively the value of the "Last-Modified" header.

Raises a ValueError if the parsing fails or the value is not a correctly formatted time.

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proc body(response: Response): string {...}{.raises: [Defect, IOError, OSError],
                                    tags: [ReadIOEffect].}

Retrieves the specified response's body.

The response's body stream is read synchronously.

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proc body(response: AsyncResponse): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect].}
Reads the response's body and caches it. The read is performed only once.   Source Edit
proc newProxy(url: string; auth = ""): Proxy {...}{.raises: [], tags: [].}
Constructs a new TProxy object.   Source Edit
proc newMultipartData(): MultipartData {...}{.raises: [], tags: [].}
Constructs a new MultipartData object.   Source Edit
proc add(p: var MultipartData; name, content: string; filename: string = "";
        contentType: string = "") {...}{.raises: [ValueError], tags: [].}
Add a value to the multipart data. Raises a ValueError exception if name, filename or contentType contain newline characters.   Source Edit
proc add(p: var MultipartData; xs: MultipartEntries): MultipartData {...}{.discardable,
    raises: [ValueError], tags: [].}
Add a list of multipart entries to the multipart data p. All values are added without a filename and without a content type.
data.add({"action": "login", "format": "json"})
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proc newMultipartData(xs: MultipartEntries): MultipartData {...}{.raises: [ValueError],
    tags: [].}
Create a new multipart data object and fill it with the entries xs directly.
var data = newMultipartData({"action": "login", "format": "json"})
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proc addFiles(p: var MultipartData; xs: openArray[tuple[name, file: string]]): MultipartData {...}{.
    discardable, raises: [ValueError, IOError], tags: [ReadIOEffect].}
Add files to a multipart data object. The file will be opened from your disk, read and sent with the automatically determined MIME type. Raises an IOError if the file cannot be opened or reading fails. To manually specify file content, filename and MIME type, use []= instead.
data.addFiles({"uploaded_file": "public/test.html"})
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proc `[]=`(p: var MultipartData; name, content: string) {...}{.raises: [ValueError], tags: [].}
Add a multipart entry to the multipart data p. The value is added without a filename and without a content type.
data["username"] = "NimUser"
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proc `[]=`(p: var MultipartData; name: string;
          file: tuple[name, contentType, content: string]) {...}{.raises: [ValueError],
    tags: [].}
Add a file to the multipart data p, specifying filename, contentType and content manually.
data["uploaded_file"] = ("test.html", "text/html",
  "<html><head></head><body><p>test</p></body></html>")
  Source Edit
proc newHttpClient(userAgent = defUserAgent; maxRedirects = 5;
                  sslContext = getDefaultSSL(); proxy: Proxy = nil; timeout = -1): HttpClient {...}{.
    raises: [], tags: [].}

Creates a new HttpClient instance.

userAgent specifies the user agent that will be used when making requests.

maxRedirects specifies the maximum amount of redirects to follow, default is 5.

sslContext specifies the SSL context to use for HTTPS requests.

proxy specifies an HTTP proxy to use for this HTTP client's connections.

timeout specifies the number of milliseconds to allow before a TimeoutError is raised.

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proc newAsyncHttpClient(userAgent = defUserAgent; maxRedirects = 5;
                       sslContext = getDefaultSSL(); proxy: Proxy = nil): AsyncHttpClient {...}{.
    raises: [], tags: [].}

Creates a new AsyncHttpClient instance.

userAgent specifies the user agent that will be used when making requests.

maxRedirects specifies the maximum amount of redirects to follow, default is 5.

sslContext specifies the SSL context to use for HTTPS requests.

proxy specifies an HTTP proxy to use for this HTTP client's connections.

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proc close(client: HttpClient | AsyncHttpClient)
Closes any connections held by the HTTP client.   Source Edit
proc getSocket(client: HttpClient): Socket {...}{.raises: [], tags: [].}

Get network socket, useful if you want to find out more details about the connection

this example shows info about local and remote endpoints

if client.connected:
  echo client.getSocket.getLocalAddr
  echo client.getSocket.getPeerAddr
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proc getSocket(client: AsyncHttpClient): AsyncSocket {...}{.raises: [], tags: [].}
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proc request(client: AsyncHttpClient; url: string; httpMethod: string; body = "";
            headers: HttpHeaders = nil): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a request using the custom method string specified by httpMethod.

Connection will be kept alive. Further requests on the same client to the same hostname will not require a new connection to be made. The connection can be closed by using the close procedure.

This procedure will follow redirects up to a maximum number of redirects specified in client.maxRedirects.

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proc request(client: HttpClient; url: string; httpMethod: string; body = "";
            headers: HttpHeaders = nil): Response {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect], tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a request using the custom method string specified by httpMethod.

Connection will be kept alive. Further requests on the same client to the same hostname will not require a new connection to be made. The connection can be closed by using the close procedure.

This procedure will follow redirects up to a maximum number of redirects specified in client.maxRedirects.

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proc request(client: AsyncHttpClient; url: string; httpMethod = HttpGet; body = "";
            headers: HttpHeaders = nil): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a request using the method specified.

Connection will be kept alive. Further requests on the same client to the same hostname will not require a new connection to be made. The connection can be closed by using the close procedure.

When a request is made to a different hostname, the current connection will be closed.

  Source Edit
proc request(client: HttpClient; url: string; httpMethod = HttpGet; body = "";
            headers: HttpHeaders = nil): Response {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect], tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a request using the method specified.

Connection will be kept alive. Further requests on the same client to the same hostname will not require a new connection to be made. The connection can be closed by using the close procedure.

When a request is made to a different hostname, the current connection will be closed.

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proc head(client: AsyncHttpClient; url: string): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a HEAD request.

This procedure uses httpClient values such as client.maxRedirects.

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proc head(client: HttpClient; url: string): Response {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect], tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a HEAD request.

This procedure uses httpClient values such as client.maxRedirects.

  Source Edit
proc get(client: AsyncHttpClient; url: string): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a GET request.

This procedure uses httpClient values such as client.maxRedirects.

  Source Edit
proc get(client: HttpClient; url: string): Response {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect], tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}

Connects to the hostname specified by the URL and performs a GET request.

This procedure uses httpClient values such as client.maxRedirects.

  Source Edit
proc getContent(client: AsyncHttpClient; url: string): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a GET request.   Source Edit
proc getContent(client: HttpClient; url: string): string {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a GET request.   Source Edit
proc delete(client: AsyncHttpClient; url: string): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a DELETE request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc delete(client: HttpClient; url: string): Response {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect], tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a DELETE request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc deleteContent(client: AsyncHttpClient; url: string): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a DELETE request.   Source Edit
proc deleteContent(client: HttpClient; url: string): string {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a DELETE request.   Source Edit
proc post(client: AsyncHttpClient; url: string; body = "";
         multipart: MultipartData = nil): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a POST request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc post(client: HttpClient; url: string; body = ""; multipart: MultipartData = nil): Response {...}{.raises: [
    ValueError, HttpRequestError, SslError, OSError, IOError, TimeoutError,
    ProtocolError, KeyError, Defect],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a POST request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc postContent(client: AsyncHttpClient; url: string; body = "";
                multipart: MultipartData = nil): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a POST request.   Source Edit
proc postContent(client: HttpClient; url: string; body = "";
                multipart: MultipartData = nil): string {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a POST request.   Source Edit
proc put(client: AsyncHttpClient; url: string; body = ""; multipart: MultipartData = nil): Future[
    AsyncResponse] {...}{.raises: [Exception, ValueError, FutureError],
                    tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a PUT request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc put(client: HttpClient; url: string; body = ""; multipart: MultipartData = nil): Response {...}{.raises: [
    ValueError, HttpRequestError, SslError, OSError, IOError, TimeoutError,
    ProtocolError, KeyError, Defect],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a PUT request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc putContent(client: AsyncHttpClient; url: string; body = "";
               multipart: MultipartData = nil): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL andreturns the content of a PUT request.   Source Edit
proc putContent(client: HttpClient; url: string; body = "";
               multipart: MultipartData = nil): string {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL andreturns the content of a PUT request.   Source Edit
proc patch(client: AsyncHttpClient; url: string; body = "";
          multipart: MultipartData = nil): Future[AsyncResponse] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a PATCH request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc patch(client: HttpClient; url: string; body = ""; multipart: MultipartData = nil): Response {...}{.raises: [
    ValueError, HttpRequestError, SslError, OSError, IOError, TimeoutError,
    ProtocolError, KeyError, Defect],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and performs a PATCH request. This procedure uses httpClient values such as client.maxRedirects.   Source Edit
proc patchContent(client: AsyncHttpClient; url: string; body = "";
                 multipart: MultipartData = nil): Future[string] {...}{.
    raises: [Exception, ValueError, FutureError], tags: [RootEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a PATCH request.   Source Edit
proc patchContent(client: HttpClient; url: string; body = "";
                 multipart: MultipartData = nil): string {...}{.raises: [ValueError,
    HttpRequestError, SslError, OSError, IOError, TimeoutError, ProtocolError,
    KeyError, Defect, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Connects to the hostname specified by the URL and returns the content of a PATCH request.   Source Edit
proc downloadFile(client: HttpClient; url: string; filename: string) {...}{.raises: [
    ValueError, HttpRequestError, SslError, OSError, IOError, TimeoutError,
    ProtocolError, KeyError, Defect, Exception, OverflowError],
    tags: [ReadIOEffect, WriteIOEffect, TimeEffect].}
Downloads url and saves it to filename.   Source Edit
proc downloadFile(client: AsyncHttpClient; url: string; filename: string): Future[void] {...}{.
    raises: [FutureError, Exception], tags: [RootEffect, TimeEffect].}
  Source Edit