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http.head()

Definition

http.head()

Sends an HTTP HEAD request to the specified URL using the MongoDB Realm HTTP Service.

Usage

Example

Note

This example assumes you have configured an HTTP service called “myHttp”. If you do not need this HTTP action validated with Service Rules, you can use the context.http module.

exports = function() {
  const http = context.services.get("myHttp");
  return http
    .head({ url: "https://www.example.com/users" })
    .then(response => {
      // The response body is encoded as raw BSON.Binary. Parse it to JSON.
      const ejson_body = EJSON.parse(response.body.text());
      return ejson_body;
    })
};
// 1. Instantiate an HTTP Service Client
let app = Realm.defaultAppClient!
let http = app.serviceClient(
  fromFactory: httpServiceClientFactory,
  withName: "myHttp"
)

// 2. Build a new HTTPRequest
let request: HTTPRequest = HTTPRequestBuilder()
  .with(method: HTTPMethod.head)
  .with(url: "https://www.example.com/users")
  .build()

// 3. Execute the built request
http.execute(request) { result in
  switch result {
  case .success:
    print("Successfully sent HEAD request!")
  case .failure(let error):
    print("Error sending HEAD request: \(error)")
  }
}
// 1. Instantiate an HTTP Service Client
RealmAppClient client = Realm.getDefaultAppClient();
RealmServiceClient http = client.getServiceClient(HttpServiceClient.factory, "myHttp");

// 2. Build a new HttpRequest
HttpRequest request = new HttpRequest.Builder()
  .withMethod(HttpMethod.HEAD)
  .withUrl("https://www.example.com/users")
  .build();

// 3. Execute the built request
http.execute(request)
  .addOnCompleteListener(new OnCompleteListener<Void>() {
    @Override
    public void onComplete(@NonNull final Task<Void> task) {
      if (task.isSuccessful()) { Log.d("realm", "Successfully sent HEAD request!"); } else { Log.e("realm", "Error sending HEAD request:", task.getException()); }
    }
  });
import { Realm } from 'mongodb-realm-browser-sdk';
import {
  HttpServiceClient,
  HttpRequest,
  HttpMethod
} from 'mongodb-realm-browser-services-http';

// 1. Instantiate an HTTP Service Client
const app = Realm.defaultAppClient;
const http = app.getServiceClient(HttpServiceClient.factory, "myHttp");

// 2. Build a new HttpRequest
const request = new HttpRequest.Builder()
  .withMethod(HttpMethod.HEAD)
  .withUrl("https://www.example.com/users")
  .build()

// 3. Execute the built request
http.execute(request)
  .then(console.log)
  .catch(console.error)

Parameters

The http.head() action accepts one argument of the following form:

{
    "url": <string>,
    "headers": <document>,
    "cookies": <string>,
    "authUrl": <string>,
    "followRedirects": <boolean>
}
Field Description

Request URL

url: <string>
Required. The target URL for the HTTP request. Alternatively, you can specify the components of the URL as root-level fields. See Alternative URL Arguments.

Request Headers

headers: <document>

Optional. A document where each field name corresponds to a type of HTTP header and each field value is an array of one or more string values for that header.

Example

{
  "Content-Type": [ "application/json" ]
}

Request Cookies

cookies: <document>

Optional. A document where each field name corresponds to a cookie name and each field value is that cookie’s string value.

Example

{
  "favoriteTeam": "Chicago Cubs"
}

Digest Authentication

digestAuth: <boolean>
Optional. If true, Realm authenticates the request using digest authentication. You must specify a username and password (either as fields in the request document or as part of the URL) to use digest authentication. For more details, see Request Authentication.

Request Authentication URL

authUrl: <string>
Optional. A URL that grants authorization cookies for the HTTP request.

Follow Redirects

followRedirects: <boolean>
Optional. If true, the request will follow any HTTP redirects it receives for the target URL.

You can configure HTTP HEAD request parameters with the following builder methods:

Builder Method Description

HTTP Method

.withMethod(<HttpMethod>)
.withMethod(<HttpMethod>)
.with(method: <HTTPMethod>)

Required. The HTTP method of the request. For HEAD requests, use the following:

.withMethod(HttpMethod.HEAD)
.withMethod(HttpMethod.HEAD)
.with(method: HTTPMethod.head)

Request URL

.withUrl(<string>)
.withUrl(<string>)
.with(url: <string>)
Required. The target URL for the HTTP request.

Request Headers

.withHeaders(<document>)
.withHeaders(<document>)
.with(headers: <document>)

Optional. A document where each field name corresponds to a type of HTTP header and each field value is an array of one or more string values for that header.

Example

{
  "Content-Type": [ "application/json" ]
}

Request Cookies

.withCookies(<document>)
.withCookies(<document>)
.with(cookies: <document>)

Optional. A document where each field name corresponds to a cookie name and each field value is that cookie’s string value.

Example

{
  "favoriteTeam": "Chicago Cubs"
}

Request Authentication URL

.withAuthUrl(<string>)
.withAuthUrl(<string>)
.with(authURL: <string>)
Optional. A URL that grants authorization cookies for the HTTP request.

Follow Redirects

.withFollowRedirects(<boolean>)
.withFollowRedirects(<boolean>)
.with(followRedirects: <boolean>)
Optional. If true, the request will follow any HTTP redirects it receives for the target URL.

You can configure HTTP HEAD request parameters with the following builder methods:

Builder Method Description

HTTP Method

.withMethod(<HttpMethod>)
.withMethod(<HttpMethod>)
.with(method: <HTTPMethod>)

Required. The HTTP method of the request. For HEAD requests, use the following:

.withMethod(HttpMethod.HEAD)
.withMethod(HttpMethod.HEAD)
.with(method: HTTPMethod.head)

Request URL

.withUrl(<string>)
.withUrl(<string>)
.with(url: <string>)
Required. The target URL for the HTTP request.

Request Headers

.withHeaders(<document>)
.withHeaders(<document>)
.with(headers: <document>)

Optional. A document where each field name corresponds to a type of HTTP header and each field value is an array of one or more string values for that header.

Example

{
  "Content-Type": [ "application/json" ]
}

Request Cookies

.withCookies(<document>)
.withCookies(<document>)
.with(cookies: <document>)

Optional. A document where each field name corresponds to a cookie name and each field value is that cookie’s string value.

Example

{
  "favoriteTeam": "Chicago Cubs"
}

Request Authentication URL

.withAuthUrl(<string>)
.withAuthUrl(<string>)
.with(authURL: <string>)
Optional. A URL that grants authorization cookies for the HTTP request.

Follow Redirects

.withFollowRedirects(<boolean>)
.withFollowRedirects(<boolean>)
.with(followRedirects: <boolean>)
Optional. If true, the request will follow any HTTP redirects it receives for the target URL.

You can configure HTTP HEAD request parameters with the following builder methods:

Builder Method Description

HTTP Method

.withMethod(<HttpMethod>)
.withMethod(<HttpMethod>)
.with(method: <HTTPMethod>)

Required. The HTTP method of the request. For HEAD requests, use the following:

.withMethod(HttpMethod.HEAD)
.withMethod(HttpMethod.HEAD)
.with(method: HTTPMethod.head)

Request URL

.withUrl(<string>)
.withUrl(<string>)
.with(url: <string>)
Required. The target URL for the HTTP request.

Request Headers

.withHeaders(<document>)
.withHeaders(<document>)
.with(headers: <document>)

Optional. A document where each field name corresponds to a type of HTTP header and each field value is an array of one or more string values for that header.

Example

{
  "Content-Type": [ "application/json" ]
}

Request Cookies

.withCookies(<document>)
.withCookies(<document>)
.with(cookies: <document>)

Optional. A document where each field name corresponds to a cookie name and each field value is that cookie’s string value.

Example

{
  "favoriteTeam": "Chicago Cubs"
}

Request Authentication URL

.withAuthUrl(<string>)
.withAuthUrl(<string>)
.with(authURL: <string>)
Optional. A URL that grants authorization cookies for the HTTP request.

Follow Redirects

.withFollowRedirects(<boolean>)
.withFollowRedirects(<boolean>)
.with(followRedirects: <boolean>)
Optional. If true, the request will follow any HTTP redirects it receives for the target URL.

Alternative URL Parameters

If you need to specify the individual components of the request’s target URL, omit the url field and specify the components as root-level fields. The following URL component fields are available:

<scheme>://<host>/<path>?<query>#<fragment>
{
   "scheme": <string>,
   "host": <string>,
   "path": <string>,
   "query": <document>,
   "fragment": <string>,
   "username": <string>,
   "password": <string>
}
Name Contents
scheme
Optional. Default: "http".
Valid options: https, http

The URL scheme.

Example

// https://www.example.com/
{ scheme: "https" }
host
Required.

The hostname of the target resource.

Example

// https://www.example.com/
{ host: "www.example.com" }
path
Optional.

The path of the target resource.

Example

// https://www.example.com/api/v1/users
{ path: "/api/v1/users" }
query
Optional.

A document where each field maps to a parameter in the URL query string. The value of each field is an array of strings that contains all arguments for the parameter.

Example

// https://www.example.com/?id=8675309&color=red&color=blue
{
  query: {
    "id": ["8675309"],
    "color": ["red", "blue"]
  }
}
fragment
Optional.

The URL fragment. This portion of the URL includes everything after the hash (#) symbol.

Example

// https://www.example.com/?id=8675309#someFragment
{ fragment: "someFragment" }
username
Optional.

The username with which to authenticate the request. Typically, users utilize this argument with the password argument.

password
Optional.

The password with which to authenticate the request. The password should correspond to the user specified in the username argument.

Return Value

The http.head() action returns a promise that resolves to a document with the following form:

{
   "status": <string>,
   "statusCode": <integer>,
   "contentLength": <integer>,
   "headers": <document>,
   "cookies": <array>,
   "body": <binary>
}
Field Type Description
status string The HTTP Request status message.
statusCode integer The HTTP Request status code.
contentLength integer The number of bytes returned in the response body.
headers document

A document where each field name corresponds to a type of HTTP header and each field value is an array of one or more string values for that header.

Example

{
  "Content-Type": [ "application/json" ]
}
cookies document

A document where each field name corresponds to a cookie name, and each field value is that cookie’s string value.

Example

{
  "favoriteTeam": "Chicago Cubs"
}
body binary The binary-encoded body of the HTTP response.

Request Authentication

You can authenticate an outbound HTTP request using one of the standard HTTP authentication schemes. MongoDB Realm supports the following authentication schemes:

Basic Authentication

HTTP basic authentication requires that incoming requests include a valid username and password for the requested service. You can specify the user credentials in the username and password fields of the request document, directly in a url string, or in an Authorization HTTP header.

Example

The following examples demonstrate three equivalent ways to authenticate an HTTP service request using basic authentication. The examples all use the username MyUser and the password Mypassw0rd.

Specify Credentials Directly (Best Method)
{
  "scheme": "https",
  "username": "MyUser",
  "password": "Mypassw0rd",
  "domain": "www.example.com"
}
Embed Credentials in the URL
{
  "url": "https://MyUser:Mypassw0rd@www.example.com"
}
Include an Authorization Header
{
  "url": "https://www.example.com",
  "headers": {
    "Authorization": [
      `Basic ${BSON.Binary.fromText("MyUser:Mypassw0rd").toBase64()}`
    ]
  }
}

Digest Authentication

HTTP digest authentication requires that incoming requests include an authorization key based on a random nonce value returned from the server. Realm can automatically construct the key and authorize requests given a valid username and password.

To configure a request to use digest authentication, set the digestAuth field to true and specify the user credentials in the username and password fields of the request document or directly in a url string.

Example

The following examples demonstrate two equivalent ways to authenticate an HTTP service request using digest authentication. The examples all use the username MyUser and the password Mypassw0rd.

Specify Credentials Directly (Best Method)
{
  "scheme": "https",
  "username": "MyUser",
  "password": "Mypassw0rd",
  "domain": "www.example.com",
  "digestAuth": true
}
Embed Credentials in the URL
{
  "url": "https://MyUser:Mypassw0rd@www.example.com",
  "digestAuth": true
}

Rule Templates

Users Can Only Send Requests to a Specific Host

{
  "%%args.url.host": "example.com"
}

Requests URLs Must Include a Specific Query Parameter

{
  "%%args.url.query.someParameter": "importantValue"
}

Requests Must Be to a Specific Path

{
  "%%args.url.scheme: "https",
  "%%args.url.host" : "www.example.com",
  "%%args.url.path" : "/api/v1.0/messages"
}