HttpRequest class

A client-side XHR request for getting data from a URL, formally known as XMLHttpRequest.

HttpRequest can be used to obtain data from HTTP and FTP protocols, and is useful for AJAX-style page updates.

The simplest way to get the contents of a text file, such as a JSON-formatted file, is with getString. For example, the following code gets the contents of a JSON file and prints its length:

var path = 'myData.json';
HttpRequest.getString(path)
    .then((String fileContents) {
      print(fileContents.length);
    })
    .catchError((Error error) {
      print(error.toString());
    });

Fetching data from other servers

For security reasons, browsers impose restrictions on requests made by embedded apps. With the default behavior of this class, the code making the request must be served from the same origin (domain name, port, and application layer protocol) as the requested resource. In the example above, the myData.json file must be co-located with the app that uses it. You might be able to get around this restriction by using CORS headers or JSONP.

Other resources

Fetch Data Dynamically,a tutorial from A Game of Darts,shows two different ways to use HttpRequest to get a JSON file.
Get Input from a Form,another tutorial from A Game of Darts,shows using HttpRequest with a custom server.
Dart article on using HttpRequests
JS XMLHttpRequest
Using XMLHttpRequest

Inheritance

Annotations

@DomName('XMLHttpRequest')

Constants

DONE → int @DocsEditable(), @DomName('XMLHttpRequest.DONE'): 4
HEADERS_RECEIVED → int @DocsEditable(), @DomName('XMLHttpRequest.HEADERS_RECEIVED'): 2
LOADING → int @DocsEditable(), @DomName('XMLHttpRequest.LOADING'): 3
OPENED → int @DocsEditable(), @DomName('XMLHttpRequest.OPENED'): 1
readyStateChangeEvent → EventStreamProvider<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequest.readystatechangeEvent'): Static factory designed to expose readystatechange events to event handlers that are not necessarily instances of HttpRequest.

const EventStreamProvider<ProgressEvent>('readystatechange')
UNSENT → int @DocsEditable(), @DomName('XMLHttpRequest.UNSENT'): 0

Static Properties

instanceRuntimeType → Type @Deprecated("Internal Use Only"), read-only
supportsCrossOrigin → bool read-only: Checks to see if the current platform supports making cross origin requests.
supportsLoadEndEvent → bool read-only: Checks to see if the LoadEnd event is supported on the current platform.
supportsOverrideMimeType → bool read-only: Checks to see if the overrideMimeType method is supported on the current platform.
supportsProgressEvent → bool read-only: Checks to see if the Progress event is supported on the current platform.

Static Methods

getString(String url, { bool withCredentials, void onProgress(ProgressEvent e) }) → Future<String>: Creates a GET request for the specified url.
postFormData(String url, Map<String, String> data, { bool withCredentials, String responseType, Map<String, String> requestHeaders, void onProgress(ProgressEvent e) }) → Future<HttpRequest>: Makes a server POST request with the specified data encoded as form data.
request(String url, { String method, bool withCredentials, String responseType, String mimeType, Map<String, String> requestHeaders, sendData, void onProgress(ProgressEvent e) }) → Future<HttpRequest>: Creates and sends a URL request for the specified url.
requestCrossOrigin(String url, { String method, String sendData }) → Future<String> @Experimental(): Makes a cross-origin request to the specified URL.

Constructors

HttpRequest() factory: General constructor for any type of request (GET, POST, etc).
HttpRequest.internal_()

Properties

onReadyStateChange → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequest.onreadystatechange'), read-only: Event listeners to be notified every time the HttpRequest object's readyState changes values.
readyState → int @DocsEditable(), @DomName('XMLHttpRequest.readyState'), read-only: Indicator of the current state of the request:
response → Object @DocsEditable(), @DomName('XMLHttpRequest.response'), @SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only: The data received as a reponse from the request.
responseHeaders → Map<String, String> read-only: Returns all response headers as a key-value map.
responseText → String @DocsEditable(), @DomName('XMLHttpRequest.responseText'), read-only: The response in String form or empty String on failure.
responseType → String @DocsEditable(), @DomName('XMLHttpRequest.responseType'), read / write: String telling the server the desired response format.
responseUrl → String @DocsEditable(), @DomName('XMLHttpRequest.responseURL'), @Experimental(), read-only
responseXml → Document @DocsEditable(), @DomName('XMLHttpRequest.responseXML'), read-only: The request response, or null on failure.
status → int @DocsEditable(), @DomName('XMLHttpRequest.status'), read-only: The HTTP result code from the request (200, 404, etc). See also: HTTP Status Codes
statusText → String @DocsEditable(), @DomName('XMLHttpRequest.statusText'), read-only: The request response string (such as "200 OK"). See also: HTTP Status Codes
timeout → int @DocsEditable(), @DomName('XMLHttpRequest.timeout'), @Experimental(), read / write: Length of time in milliseconds before a request is automatically terminated.
upload → HttpRequestUpload @DocsEditable(), @DomName('XMLHttpRequest.upload'), @Unstable(), read-only: EventTarget that can hold listeners to track the progress of the request. The events fired will be members of HttpRequestUploadEvents.
withCredentials → bool @DocsEditable(), @DomName('XMLHttpRequest.withCredentials'), read / write: True if cross-site requests should use credentials such as cookies or authorization headers; false otherwise.
hashCode → int read-only, inherited
on → Events read-only, inherited: This is an ease-of-use accessor for event streams which should only be used when an explicit accessor is not available.
onAbort → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onabort'), @Experimental(), read-only, inherited: Stream of abort events handled by this HttpRequestEventTarget.
onError → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onerror'), @Experimental(), read-only, inherited: Stream of error events handled by this HttpRequestEventTarget.
onLoad → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onload'), @Experimental(), read-only, inherited: Stream of load events handled by this HttpRequestEventTarget.
onLoadEnd → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onloadend'), @Experimental(), @SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only, inherited: Stream of loadend events handled by this HttpRequestEventTarget.
onLoadStart → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onloadstart'), @Experimental(), read-only, inherited: Stream of loadstart events handled by this HttpRequestEventTarget.
onProgress → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.onprogress'), @Experimental(), @SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.IE, '10'), @SupportedBrowser(SupportedBrowser.SAFARI), read-only, inherited: Stream of progress events handled by this HttpRequestEventTarget.
onTimeout → Stream<ProgressEvent> @DocsEditable(), @DomName('XMLHttpRequestEventTarget.ontimeout'), @Experimental(), read-only, inherited: Stream of timeout events handled by this HttpRequestEventTarget.
runtimeType → Type read-only, inherited: A representation of the runtime type of the object.

Operators

operator ==(other) → bool inherited: The equality operator.

Methods

abort() → void @DocsEditable(), @DomName('XMLHttpRequest.abort'): Stop the current request.
getAllResponseHeaders() → String @DocsEditable(), @DomName('XMLHttpRequest.getAllResponseHeaders'), @Unstable(): Retrieve all the response headers from a request.
getResponseHeader(String name) → String @DocsEditable(), @DomName('XMLHttpRequest.getResponseHeader'), @Unstable(): Return the response header named header, or null if not found.
open(String method, String url, { bool async, String user, String password }) → void @DocsEditable(), @DomName('XMLHttpRequest.open'): Specify the desired url, and method to use in making the request.
overrideMimeType(String mime) → void @DocsEditable(), @DomName('XMLHttpRequest.overrideMimeType'), @SupportedBrowser(SupportedBrowser.CHROME), @SupportedBrowser(SupportedBrowser.FIREFOX), @SupportedBrowser(SupportedBrowser.SAFARI): Specify a particular MIME type (such as text/xml) desired for the response.
send([body_OR_data ]) → void
setRequestHeader(String name, String value) → void @DocsEditable(), @DomName('XMLHttpRequest.setRequestHeader'): Sets the value of an HTTP request header.
addEventListener(String type, EventListener listener, [ bool useCapture ]) → void inherited
dispatchEvent(Event event) → bool @DocsEditable(), @DomName('EventTarget.dispatchEvent'), inherited
noSuchMethod(Invocation invocation) → dynamic inherited: Invoked when a non-existent method or property is accessed.
removeEventListener(String type, EventListener listener, [ bool useCapture ]) → void inherited
toString() → String inherited: Returns the result of the JavaScript objects toString method.

© 2012 the Dart project authors
Licensed under the Creative Commons Attribution-ShareAlike License v4.0.
https://api.dartlang.org/stable/1.24.3/dart-html/HttpRequest-class.html