15 KiB
SuperAgent
Super Agent is light-weight progressive ajax API crafted for flexibility, readability, and a low learning curve after being frustrated with many of the existing request APIs. It also works with Node.js!
request
.post('/api/pet')
.send({ name: 'Manny', species: 'cat' })
.set('X-API-Key', 'foobar')
.set('Accept', 'application/json')
.end(function(err, res){
if (err || !res.ok) {
alert('Oh no! error');
} else {
alert('yay got ' + JSON.stringify(res.body));
}
});
Test documentation
The following test documentation was generated with Mocha's "doc" reporter, and directly reflects the test suite. This provides an additional source of documentation.
Request basics
A request can be initiated by invoking the appropriate method on the request object, then calling .end() to send the request. For example a simple GET request:
request
.get('/search')
.end(function(err, res){
});
A method string may also be passed:
request('GET', '/search').end(callback);
The node client may also provide absolute urls:
request
.get('http://example.com/search')
.end(function(err, res){
});
DELETE, HEAD, POST, PUT and other HTTP verbs may also be used, simply change the method name:
request
.head('/favicon.ico')
.end(function(err, res){
});
DELETE is a special-case, as it's a reserved word, so the method is named .del():
request
.del('/user/1')
.end(function(err, res){
});
The HTTP method defaults to GET, so if you wish, the following is valid:
request('/search', function(err, res){
});
Setting header fields
Setting header fields is simple, invoke .set() with a field name and value:
request
.get('/search')
.set('API-Key', 'foobar')
.set('Accept', 'application/json')
.end(callback);
You may also pass an object to set several fields in a single call:
request
.get('/search')
.set({ 'API-Key': 'foobar', Accept: 'application/json' })
.end(callback);
GET requests
The .query() method accepts objects, which when used with the GET method will form a query-string. The following will produce the path /search?query=Manny&range=1..5&order=desc.
request
.get('/search')
.query({ query: 'Manny' })
.query({ range: '1..5' })
.query({ order: 'desc' })
.end(function(err, res){
});
Or as a single object:
request
.get('/search')
.query({ query: 'Manny', range: '1..5', order: 'desc' })
.end(function(err, res){
});
The .query() method accepts strings as well:
request
.get('/querystring')
.query('search=Manny&range=1..5')
.end(function(err, res){
});
Or joined:
request
.get('/querystring')
.query('search=Manny')
.query('range=1..5')
.end(function(err, res){
});
HEAD requests
You can also use the .query() method for HEAD requests. The following will produce the path /users?email=joe@smith.com.
request
.head('/users')
.query({ email: 'joe@smith.com' })
.end(function(err, res){
});
POST / PUT requests
A typical JSON POST request might look a little like the following, where we set the Content-Type header field appropriately, and "write" some data, in this case just a JSON string.
request.post('/user')
.set('Content-Type', 'application/json')
.send('{"name":"tj","pet":"tobi"}')
.end(callback)
Since JSON is undoubtably the most common, it's the default! The following example is equivalent to the previous.
request.post('/user')
.send({ name: 'tj', pet: 'tobi' })
.end(callback)
Or using multiple .send() calls:
request.post('/user')
.send({ name: 'tj' })
.send({ pet: 'tobi' })
.end(callback)
By default sending strings will set the Content-Type to application/x-www-form-urlencoded,
multiple calls will be concatenated with &, here resulting in name=tj&pet=tobi:
request.post('/user')
.send('name=tj')
.send('pet=tobi')
.end(callback);
SuperAgent formats are extensible, however by default "json" and "form" are supported. To send the data as application/x-www-form-urlencoded simply invoke .type() with "form", where the default is "json". This request will POST the body "name=tj&pet=tobi".
request.post('/user')
.type('form')
.send({ name: 'tj' })
.send({ pet: 'tobi' })
.end(callback)
Note: "form" is aliased as "form-data" and "urlencoded" for backwards compat.
Setting the Content-Type
The obvious solution is to use the .set() method:
request.post('/user')
.set('Content-Type', 'application/json')
As a short-hand the .type() method is also available, accepting
the canonicalized MIME type name complete with type/subtype, or
simply the extension name such as "xml", "json", "png", etc:
request.post('/user')
.type('application/json')
request.post('/user')
.type('json')
request.post('/user')
.type('png')
Setting Accept
In a similar fashion to the .type() method it is also possible to set the Accept header via the short hand method .accept(). Which references request.types as well allowing you to specify either the full canonicalized MIME type name as type/subtype, or the extension suffix form as "xml", "json", "png", etc for convenience:
request.get('/user')
.accept('application/json')
request.get('/user')
.accept('json')
request.post('/user')
.accept('png')
Query strings
res.query(obj) is a method which may be used to build up a query-string. For example populating ?format=json&dest=/login on a POST:
request
.post('/')
.query({ format: 'json' })
.query({ dest: '/login' })
.send({ post: 'data', here: 'wahoo' })
.end(callback);
Parsing response bodies
Super Agent will parse known response-body data for you, currently supporting application/x-www-form-urlencoded, application/json, and multipart/form-data.
JSON / Urlencoded
The property res.body is the parsed object, for example if a request responded with the JSON string '{"user":{"name":"tobi"}}', res.body.user.name would be "tobi". Likewise the x-www-form-urlencoded value of "user[name]=tobi" would yield the same result.
Multipart
The Node client supports multipart/form-data via the Formidable module. When parsing multipart responses, the object res.files is also available to you. Suppose for example a request responds with the following multipart body:
--whoop
Content-Disposition: attachment; name="image"; filename="tobi.png"
Content-Type: image/png
... data here ...
--whoop
Content-Disposition: form-data; name="name"
Content-Type: text/plain
Tobi
--whoop--
You would have the values res.body.name provided as "Tobi", and res.files.image as a File object containing the path on disk, filename, and other properties.
Response properties
Many helpful flags and properties are set on the Response object, ranging from the response text, parsed response body, header fields, status flags and more.
Response text
The res.text property contains the unparsed response body string. This
property is always present for the client API, and only when the mime type
matches "text/", "/json", or "x-www-form-urlencoding" by default for node. The
reasoning is to conserve memory, as buffering text of large bodies such as multipart files or images is extremely inefficient.
To force buffering see the "Buffering responses" section.
Response body
Much like SuperAgent can auto-serialize request data, it can also automatically parse it. When a parser is defined for the Content-Type, it is parsed, which by default includes "application/json" and "application/x-www-form-urlencoded". The parsed object is then available via res.body.
Response header fields
The res.header contains an object of parsed header fields, lowercasing field names much like node does. For example res.header['content-length'].
Response Content-Type
The Content-Type response header is special-cased, providing res.type, which is void of the charset (if any). For example the Content-Type of "text/html; charset=utf8" will provide "text/html" as res.type, and the res.charset property would then contain "utf8".
Response status
The response status flags help determine if the request was a success, among other useful information, making SuperAgent ideal for interacting with RESTful web services. These flags are currently defined as:
var type = status / 100 | 0;
// status / class
res.status = status;
res.statusType = type;
// basics
res.info = 1 == type;
res.ok = 2 == type;
res.clientError = 4 == type;
res.serverError = 5 == type;
res.error = 4 == type || 5 == type;
// sugar
res.accepted = 202 == status;
res.noContent = 204 == status || 1223 == status;
res.badRequest = 400 == status;
res.unauthorized = 401 == status;
res.notAcceptable = 406 == status;
res.notFound = 404 == status;
res.forbidden = 403 == status;
Aborting requests
To abort requests simply invoke the req.abort() method.
Request timeouts
A timeout can be applied by invoking req.timeout(ms), after which an error
will be triggered. To differentiate between other errors the err.timeout property
is set to the ms value. NOTE that this is a timeout applied to the request
and all subsequent redirects, not per request.
Basic authentication
Basic auth is currently provided by the node client in two forms, first via the URL as "user:pass":
request.get('http://tobi:learnboost@local').end(callback);
As well as via the .auth() method:
request
.get('http://local')
.auth('tobi', 'learnboost')
.end(callback);
Following redirects
By default up to 5 redirects will be followed, however you may specify this with the res.redirects(n) method:
request
.get('/some.png')
.redirects(2)
.end(callback);
Piping data
The Node client allows you to pipe data to and from the request. For example piping a file's contents as the request:
var request = require('superagent')
, fs = require('fs');
var stream = fs.createReadStream('path/to/my.json');
var req = request.post('/somewhere');
req.type('json');
stream.pipe(req);
Or piping the response to a file:
var request = require('superagent')
, fs = require('fs');
var stream = fs.createWriteStream('path/to/my.json');
var req = request.get('/some.json');
req.pipe(stream);
Multipart requests
Super Agent is also great for building multipart requests for which it provides methods .attach() and .field().
Attaching files
As mentioned a higher-level API is also provided, in the form of .attach(name, [path], [filename]) and .field(name, value). Attaching several files is simple, you can also provide a custom filename for the attachment, otherwise the basename of the attached file is used.
request
.post('/upload')
.attach('avatar', 'path/to/tobi.png', 'user.png')
.attach('image', 'path/to/loki.png')
.attach('file', 'path/to/jane.png')
.end(callback);
Field values
Much like form fields in HTML, you can set field values with the .field(name, value) method. Suppose you want to upload a few images with your name and email, your request might look something like this:
request
.post('/upload')
.field('user[name]', 'Tobi')
.field('user[email]', 'tobi@learnboost.com')
.attach('image', 'path/to/tobi.png')
.end(callback);
Compression
The node client supports compressed responses, best of all, you don't have to do anything! It just works.
Buffering responses
To force buffering of response bodies as res.text you may invoke req.buffer(). To undo the default of buffering for text responses such
as "text/plain", "text/html" etc you may invoke req.buffer(false).
When buffered the res.buffered flag is provided, you may use this to
handle both buffered and unbuffered responses in the same callback.
CORS
The .withCredentials() method enables the ability to send cookies
from the origin, however only when "Access-Control-Allow-Origin" is
not a wildcard ("*"), and "Access-Control-Allow-Credentials" is "true".
request
.get('http://localhost:4001/')
.withCredentials()
.end(function(err, res){
assert(200 == res.status);
assert('tobi' == res.text);
next();
})
Error handling
Your callback function will always be passed two arguments: error and response. If no error occurred, the first argument will be null:
request
.post('/upload')
.attach('image', 'path/to/tobi.png')
.end(function(err, res){
});
An "error" event is also emitted, with you can listen for:
request
.post('/upload')
.attach('image', 'path/to/tobi.png')
.on('error', handle)
.end(function(err, res){
});
Note that a 4xx or 5xx response with super agent are considered an error by default. For example if you get a 500 or 403 response, this status information will be available via err.status. Errors from such responses also contain an err.response field with all of the properties mentioned in "Response properties". The library behaves in this way to handle the common case of wanting success responses and treating HTTP error status codes as errors while still allowing for custom logic around specific error conditions.
Network failures, timeouts, and other errors that produce no response will contain no err.status or err.response fields.
If you wish to handle 404 or other HTTP error responses, you can query the err.status property.
When an HTTP error occurs (4xx or 5xx response) the res.error property is an Error object,
this allows you to perform checks such as:
if (err && err.status === 404) {
alert('oh no ' + res.body.message);
}
else if (err) {
// all other error types we handle generically
}
Generator support
Superagent now supports easier control flow using generators. By using a generator control flow
like co or a web framework like koa,
you can yield on any superagent method:
var res = yield request
.get('http://local')
.auth('tobi', 'learnboost')