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Request-Promise

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Deprecated!

As of Feb 11th 2020, request is fully deprecated. No new changes are expected to land. In fact, none have landed for some time. This package is also deprecated because it depends on request.

Fyi, here is the reasoning of request's deprecation and a list of alternative libraries.

The simplified HTTP request client 'request' with Promise support. Powered by Bluebird.

Request and Bluebird are pretty awesome, but I found myself using the same design pattern. Request-Promise adds a Bluebird-powered .then(...) method to Request call objects. By default, http response codes other than 2xx will cause the promise to be rejected. This can be overwritten by setting options.simple = false.

Also check out the new libraries that are very similar to request-promise v4:

Migration from v3 to v4

  1. request became a peer dependency. Thus make sure that request is installed into your project as a direct dependency. (npm install --save request)
  2. Continuation Local Storage is no longer supported. However, you can get back the support by using request-promise-any.
  3. When you migrated your transform function to v3 and had to add if (!(/^2/.test('' + response.statusCode))) { return resolveWithFullResponse ? response : body; } you may now set the option transform2xxOnly = true instead.

Migration from v2 to v3

  1. The handling of the transform function got overhauled. This has two effects:

    • StatusCodeError.response is the transformed instead of the original response now. This error is thrown for non-2xx responses when options.simple is true (default). Please update your transform functions to also cover the transformation of non-2xx responses. To get the old behavior you may add if (!(/^2/.test('' + response.statusCode))) { return resolveWithFullResponse ? response : body; } to the first line of your transform functions that are used for requests with options.simple === true. However, you may prefer updating your transform functions to being able to transform 2xx as well as non-2xx responses because this decouples their implementation from the use of the simple option when doing requests.
    • If a transform operation throws an error, the request will be rejected with a TransformError. Its cause attribute contains the error thrown by the transform operation. Previously, the request was rejected directly with the error thrown by the transform operation. Wrapping it into a TransformError makes the error handling easier.

  2. Bluebird got updated from v2 to v3. This won't make a difference for most use cases. However, if you use advanced Promise chains starting with the Promise returned by Request-Promise, please check Bluebird's new features and changes.

Installation

This module is installed via npm:

npm install --save request
npm install --save request-promise

request is defined as a peer-dependency and thus has to be installed separately.

Cheat Sheet

var rp = require('request-promise');

Since request-promise wraps around request everything that works with request also works with request-promise. Also check out the request docs for more examples.

Crawl a webpage

rp('http://www.google.com')
    .then(function (htmlString) {
        // Process html...
    })
    .catch(function (err) {
        // Crawling failed...
    });

Crawl a webpage better

var cheerio = require('cheerio'); // Basically jQuery for node.js

var options = {
    uri: 'http://www.google.com',
    transform: function (body) {
        return cheerio.load(body);
    }
};

rp(options)
    .then(function ($) {
        // Process html like you would with jQuery...
    })
    .catch(function (err) {
        // Crawling failed or Cheerio choked...
    });

GET something from a JSON REST API

var options = {
    uri: 'https://api.github.com/user/repos',
    qs: {
        access_token: 'xxxxx xxxxx' // -> uri + '?access_token=xxxxx%20xxxxx'
    },
    headers: {
        'User-Agent': 'Request-Promise'
    },
    json: true // Automatically parses the JSON string in the response
};

rp(options)
    .then(function (repos) {
        console.log('User has %d repos', repos.length);
    })
    .catch(function (err) {
        // API call failed...
    });

POST data to a JSON REST API

Set option.body to your data and json: true to encode the body as JSON. See below for HTML forms.

var options = {
    method: 'POST',
    uri: 'http://api.posttestserver.com/post',
    body: {
        some: 'payload'
    },
    json: true // Automatically stringifies the body to JSON
};

rp(options)
    .then(function (parsedBody) {
        // POST succeeded...
    })
    .catch(function (err) {
        // POST failed...
    });

POST like HTML forms do

Pass your data to options.form to encode the body the same way as HTML forms do:

var options = {
    method: 'POST',
    uri: 'http://posttestserver.com/post.php',
    form: {
        // Like <input type="text" name="name">
        name: 'Josh'
    },
    headers: {
        /* 'content-type': 'application/x-www-form-urlencoded' */ // Is set automatically
    }
};

rp(options)
    .then(function (body) {
        // POST succeeded...
    })
    .catch(function (err) {
        // POST failed...
    });

If you want to include a file upload then use options.formData:

var options = {
    method: 'POST',
    uri: 'http://posttestserver.com/post.php',
    formData: {
        // Like <input type="text" name="name">
        name: 'Jenn',
        // Like <input type="file" name="file">
        file: {
            value: fs.createReadStream('test/test.jpg'),
            options: {
                filename: 'test.jpg',
                contentType: 'image/jpg'
            }
        }
    },
    headers: {
        /* 'content-type': 'multipart/form-data' */ // Is set automatically
    }
};

rp(options)
    .then(function (body) {
        // POST succeeded...
    })
    .catch(function (err) {
        // POST failed...
    });

Include a cookie

var tough = require('tough-cookie');

// Easy creation of the cookie - see tough-cookie docs for details
let cookie = new tough.Cookie({
    key: "some_key",
    value: "some_value",
    domain: 'api.mydomain.com',
    httpOnly: true,
    maxAge: 31536000
});

// Put cookie in an jar which can be used across multiple requests
var cookiejar = rp.jar();
cookiejar.setCookie(cookie, 'https://api.mydomain.com');
// ...all requests to https://api.mydomain.com will include the cookie

var options = {
    uri: 'https://api.mydomain.com/...',
    jar: cookiejar // Tells rp to include cookies in jar that match uri
};

rp(options)
    .then(function (body) {
        // Request succeeded...
    })
    .catch(function (err) {
        // Request failed...
    });

Get the full response instead of just the body

var options = {
    method: 'DELETE',
    uri: 'http://my-server/path/to/resource/1234',
    resolveWithFullResponse: true    //  <---  <---  <---  <---
};

rp(options)
    .then(function (response) {
        console.log("DELETE succeeded with status %d", response.statusCode);
    })
    .catch(function (err) {
        // Delete failed...
    });

Get a rejection only if the request failed for technical reasons

var options = {
    uri: 'http://www.google.com/this-page-does-not-exist.html',
    simple: false    //  <---  <---  <---  <---
};

rp(options)
    .then(function (body) {
        // Request succeeded but might as well be a 404
        // Usually combined with resolveWithFullResponse = true to check response.statusCode
    })
    .catch(function (err) {
        // Request failed due to technical reasons...
    });

For more options checkout the Request docs.

API in Detail

Consider Request-Promise being:

The objects returned by request calls like rp(...) or e.g. rp.post(...) are regular Promises/A+ compliant promises and can be assimilated by any compatible promise library.

The methods .then(...), .catch(...), and .finally(...) - which you can call on the request call objects - return a full-fledged Bluebird promise. That means you have the full Bluebird API available for further chaining. E.g.: rp(...).then(...).spread(...) If, however, you need a method other than .then(...), .catch(...), or .finally(...) to be FIRST in the chain, use .promise(): rp(...).promise().bind(...).then(...)

.then(onFulfilled, onRejected)

// As a Request user you would write:
var request = require('request');

request('http://google.com', function (err, response, body) {
    if (err) {
        handleError({ error: err, response: response, ... });
    } else if (!(/^2/.test('' + response.statusCode))) { // Status Codes other than 2xx
        handleError({ error: body, response: response, ... });
    } else {
        process(body);
    }
});

// As a Request-Promise user you can now write the equivalent code:
var rp = require('request-promise');

rp('http://google.com')
    .then(process, handleError);

// The same is available for all http method shortcuts:
request.post('http://example.com/api', function (err, response, body) { ... });
rp.post('http://example.com/api').then(...);

.catch(onRejected)

rp('http://google.com')
    .catch(handleError);

// ... is syntactical sugar for:

rp('http://google.com')
    .then(null, handleError);


// However, this:
rp('http://google.com')
    .then(process)
    .catch(handleError);

// ... is safer than:
rp('http://google.com')
    .then(process, handleError);

For more info on .then(process).catch(handleError) versus .then(process, handleError), see Bluebird docs on promise anti-patterns.

.finally(onFinished)

rp('http://google.com')
    .finally(function () {
	    // This is called after the request finishes either successful or not successful.
	});

.cancel()

This method cancels the request using Bluebird's cancellation feature.

When .cancel() is called:

.promise() - For advanced use cases

In order to not pollute the Request call objects with the methods of the underlying Bluebird promise, only .then(...), .catch(...), and .finally(...) were exposed to cover most use cases. The effect is that any methods of a Bluebird promise other than .then(...), .catch(...), or .finally(...) cannot be used as the FIRST method in the promise chain:

// This works:
rp('http://google.com').then(function () { ... });
rp('http://google.com').catch(function () { ... });

// This works as well since additional methods are only used AFTER the FIRST call in the chain:
rp('http://google.com').then(function () { ... }).spread(function () { ... });
rp('http://google.com').catch(function () { ... }).error(function () { ... });

// Using additional methods as the FIRST call in the chain does not work:
// rp('http://google.com').bind(this).then(function () { ... });

// Use .promise() in these cases:
rp('http://google.com').promise().bind(this).then(function () { ... });

Fulfilled promises and the resolveWithFullResponse option

// Per default the body is passed to the fulfillment handler:
rp('http://google.com')
    .then(function (body) {
        // Process the html of the Google web page...
    });

// The resolveWithFullResponse options allows to pass the full response:
rp({ uri: 'http://google.com', resolveWithFullResponse: true })
    .then(function (response) {
        // Access response.statusCode, response.body etc.
    });

Rejected promises and the simple option

// The rejection handler is called with a reason object...
rp('http://google.com')
    .catch(function (reason) {
        // Handle failed request...
	});

// ... and would be equivalent to this Request-only implementation:
var options = { uri: 'http://google.com' };

request(options, function (err, response, body) {
    var reason;
    if (err) {
        reason = {
            cause: err,
            error: err,
            options: options,
            response: response
        };
	} else if (!(/^2/.test('' + response.statusCode))) { // Status Codes other than 2xx
        reason = {
            statusCode: response.statusCode,
            error: body,
            options: options,
            response: response
        };
    }

    if (reason) {
        // Handle failed request...
    }
});


// If you pass the simple option as false...
rp({ uri: 'http://google.com', simple: false })
    .catch(function (reason) {
        // Handle failed request...
	});

// ... the equivalent Request-only code would be:
request(options, function (err, response, body) {
    if (err) {
        var reason = {
            cause: err,
            error: err,
            options: options,
            response: response
        };
        // Handle failed request...
	}
});
// E.g. a 404 would now fulfill the promise.
// Combine it with resolveWithFullResponse = true to check the status code in the fulfillment handler.

With version 0.4 the reason objects became Error objects with identical properties to ensure backwards compatibility. These new Error types allow targeted catch blocks:

var errors = require('request-promise/errors');

rp('http://google.com')
	.catch(errors.StatusCodeError, function (reason) {
        // The server responded with a status codes other than 2xx.
        // Check reason.statusCode
	})
    .catch(errors.RequestError, function (reason) {
        // The request failed due to technical reasons.
        // reason.cause is the Error object Request would pass into a callback.
	});

The transform function

You can pass a function to options.transform to generate a custom fulfillment value when the promise gets resolved.

// Just for fun you could reverse the response body:
var options = {
	uri: 'http://google.com',
    transform: function (body, response, resolveWithFullResponse) {
        return body.split('').reverse().join('');
    }
};

rp(options)
    .then(function (reversedBody) {
        // ;D
    });


// However, you could also do something useful:
var $ = require('cheerio'); // Basically jQuery for node.js

function autoParse(body, response, resolveWithFullResponse) {
    // FIXME: The content type string could contain additional values like the charset.
    // Consider using the `content-type` library for a robust comparison.
    if (response.headers['content-type'] === 'application/json') {
        return JSON.parse(body);
    } else if (response.headers['content-type'] === 'text/html') {
        return $.load(body);
    } else {
        return body;
    }
}

options.transform = autoParse;

rp(options)
    .then(function (autoParsedBody) {
        // :)
    });


// You can go one step further and set the transform as the default:
var rpap = rp.defaults({ transform: autoParse });

rpap('http://google.com')
    .then(function (autoParsedBody) {
        // :)
    });

rpap('http://echojs.com')
    .then(function (autoParsedBody) {
        // =)
    });

The third resolveWithFullResponse parameter of the transform function is equivalent to the option passed with the request. This allows to distinguish whether just the transformed body or the whole response shall be returned by the transform function:

function reverseBody(body, response, resolveWithFullResponse) {
    response.body = response.body.split('').reverse().join('');
    return resolveWithFullResponse ? response : response.body;
}

As of Request-Promise v3 the transform function is ALWAYS executed for non-2xx responses. When options.simple is set to true (default) then non-2xx responses are rejected with a StatusCodeError. In this case the error contains the transformed response:

var options = {
	uri: 'http://the-server.com/will-return/404',
	simple: true,
    transform: function (body, response, resolveWithFullResponse) { /* ... */ }
};

rp(options)
    .catch(errors.StatusCodeError, function (reason) {
        // reason.response is the transformed response
    });

You may set options.transform2xxOnly = true to only execute the transform function for responses with a 2xx status code. For other status codes – independent of any other settings, e.g. options.simple – the transform function is not executed.

Error handling

If the transform operation fails (throws an error) the request will be rejected with a TransformError:

var errors = require('request-promise/errors');

var options = {
	uri: 'http://google.com',
    transform: function (body, response, resolveWithFullResponse) {
        throw new Error('Transform failed!');
    }
};

rp(options)
    .catch(errors.TransformError, function (reason) {
        console.log(reason.cause.message); // => Transform failed!
        // reason.response is the original response for which the transform operation failed
    });

Experimental Support for Continuation Local Storage

Continuation Local Storage is no longer supported. However, you can get back the support by using request-promise-any.

Debugging

The ways to debug the operation of Request-Promise are the same as described for Request. These are:

  1. Launch the node process like NODE_DEBUG=request node script.js (lib,request,otherlib works too).
  2. Set require('request-promise').debug = true at any time (this does the same thing as #1).
  3. Use the request-debug module to view request and response headers and bodies. Instrument Request-Promise with require('request-debug')(rp);.

Mocking Request-Promise

Usually you want to mock the whole request function which is returned by require('request-promise'). This is not possible by using a mocking library like sinon.js alone. What you need is a library that ties into the module loader and makes sure that your mock is returned whenever the tested code is calling require('request-promise'). Mockery is one of such libraries.

@florianschmidt1994 kindly shared his solution:

before(function (done) {

    var filename = "fileForResponse";
    mockery.enable({
        warnOnReplace: false,
        warnOnUnregistered: false,
        useCleanCache: true
    });

    mockery.registerMock('request-promise', function () {
        var response = fs.readFileSync(__dirname + '/data/' + filename, 'utf8');
        return Bluebird.resolve(response.trim());
    });

    done();
});

after(function (done) {
    mockery.disable();
    mockery.deregisterAll();
    done();
});

describe('custom test case', function () {
    //  Test some function/module/... which uses request-promise
    //  and it will always receive the predefined "fileForResponse" as data, e.g.:
    var rp = require('request-promise');
    rp(...).then(function(data) {
        // ➞ data is what is in fileForResponse
    });
});

Based on that you may now build a more sophisticated mock. Sinon.js may be of help as well.

Contributing

To set up your development environment:

  1. clone the repo to your desktop,
  2. in the shell cd to the main folder,
  3. hit npm install,
  4. hit npm install gulp -g if you haven't installed gulp globally yet, and
  5. run gulp dev. (Or run node ./node_modules/.bin/gulp dev if you don't want to install gulp globally.)

gulp dev watches all source files and if you save some changes it will lint the code and execute all tests. The test coverage report can be viewed from ./coverage/lcov-report/index.html.

If you want to debug a test you should use gulp test-without-coverage to run all tests without obscuring the code by the test coverage instrumentation.

Change History

License (ISC)

In case you never heard about the ISC license it is functionally equivalent to the MIT license.

See the LICENSE file for details.