# HttpResponse class

An HTTP response, which returns the headers and data from the server to the client in response to an HTTP request.

Every HttpRequest object provides access to the associated HttpResponse object through the `response` property. The server sends its response to the client by writing to the HttpResponse object.

## Writing the response

This class implements IOSink. After the header has been set up, the methods from IOSink, such as `writeln()`, can be used to write the body of the HTTP response. Use the `close()` method to close the response and send it to the client.

    server.listen((HttpRequest request) {
      request.response.write('Hello, world!');
      request.response.close();
    });

When one of the IOSink methods is used for the first time, the request header is sent. Calling any methods that change the header after it is sent throws an exception.

## Setting the headers

The HttpResponse object has a number of properties for setting up the HTTP headers of the response. When writing string data through the IOSink, the encoding used is determined from the "charset" parameter of the "Content-Type" header.

    HttpResponse response = ...
    response.headers.contentType
        = new ContentType("application", "json", charset: "utf-8");
    response.write(...);  // Strings written will be UTF-8 encoded.

If no charset is provided the default of ISO-8859-1 (Latin 1) will be used.

    HttpResponse response = ...
    response.headers.add(HttpHeaders.contentTypeHeader, "text/plain");
    response.write(...);  // Strings written will be ISO-8859-1 encoded.

An exception is thrown if you use the `write()` method while an unsupported content-type is set.

Implements
  - IOSink

## Constructors

HttpResponse()

## Properties

bufferOutput ↔ bool
  Gets or sets if the `HttpResponse` should buffer output. [...]
  read / write
connectionInfo → HttpConnectionInfo
  Gets information about the client connection. Returns `null` if the socket is not available.
  read-only
contentLength ↔ int
  Gets and sets the content length of the response. If the size of the response is not known in advance set the content length to -1 - which is also the default if not set.
  read / write
cookies → List<Cookie>
  Cookies to set in the client (in the 'set-cookie' header).
  read-only
deadline ↔ Duration
  Set and get the `deadline` for the response. The deadline is timed from the time it's set. Setting a new deadline will override any previous deadline. When a deadline is exceeded, the response will be closed and any further data ignored. [...]
  read / write
headers → HttpHeaders
  Returns the response headers. [...]
  read-only
persistentConnection ↔ bool
  Gets and sets the persistent connection state. The initial value of this property is the persistent connection state from the request.
  read / write
reasonPhrase ↔ String
  Gets and sets the reason phrase. If no reason phrase is explicitly set a default reason phrase is provided. [...]
  read / write
statusCode ↔ int
  Gets and sets the status code. Any integer value is accepted. For the official HTTP status codes use the fields from `HttpStatus`. If no status code is explicitly set the default value `HttpStatus.ok` is used. [...]
  read / write
done → Future
  Get a future that will complete when the consumer closes, or when an error occurs. This future is identical to the future returned by close.
  read-only, inherited
encoding ↔ Encoding
  The `Encoding` used when writing strings. Depending on the underlying consumer this property might be mutable.
  read / write, inherited
hashCode → int
  The hash code for this object. [...]
  read-only, inherited
runtimeType → Type
  A representation of the runtime type of the object.
  read-only, inherited

## Methods

detachSocket({bool writeHeaders: true }) → Future<Socket>
  Detaches the underlying socket from the HTTP server. When the socket is detached the HTTP server will no longer perform any operations on it. [...]
redirect(Uri location, { int status: HttpStatus.movedTemporarily }) → Future
  Respond with a redirect to `location`. [...]
add(List<int> data) → void
  Adds byte `data` to the target consumer, ignoring encoding. [...]
  inherited
addError(Object error, [ StackTrace stackTrace ]) → void
  Passes the error to the target consumer as an error event. [...]
  inherited
addStream(Stream<List<int>> stream) → Future
  Adds all elements of the given `stream` to `this`. [...]
  inherited
close() → Future
  Close the target consumer. [...]
  inherited
flush() → Future
  Returns a Future that completes once all buffered data is accepted by the underlying StreamConsumer. [...]
  inherited
noSuchMethod(Invocation invocation) → dynamic
  Invoked when a non-existent method or property is accessed. [...]
  inherited
toString() → String
  Returns a string representation of this object.
  inherited
write(Object obj) → void
  Converts `obj` to a String by invoking Object.toString and adds the encoding of the result to the target consumer. [...]
  inherited
writeAll(Iterable objects, [ String separator = "" ]) → void
  Iterates over the given `objects` and writes them in sequence. [...]
  inherited
writeCharCode(int charCode) → void
  Writes the character of `charCode`. [...]
  inherited
writeln([Object obj = "" ]) → void
  Converts `obj` to a String by invoking Object.toString and writes the result to `this`, followed by a newline. [...]
  inherited

## Operators

operator ==(dynamic other) → bool
  The equality operator. [...]
  inherited