Headers for HTTP requests and responses.

In some situations, headers are immutable:

  • HttpRequest and HttpClientResponse always have immutable headers.

  • HttpResponse and HttpClientRequest have immutable headers from the moment the body is written to.

In these situations, the mutating methods throw exceptions.

For all operations on HTTP headers the header name is case-insensitive.

To set the value of a header use the set() method:

request.headers.set(HttpHeaders.CACHE_CONTROL,

'max-age=3600, must-revalidate');

To retrieve the value of a header use the value() method:

print(request.headers.value(HttpHeaders.USER_AGENT));

An HttpHeaders object holds a list of values for each name as the standard allows. In most cases a name holds only a single value, The most common mode of operation is to use set() for setting a value, and value() for retrieving a value.

Constants

dynamic ACCEPT = "accept"
const

dynamic ACCEPT_CHARSET = "accept-charset"
const

dynamic ACCEPT_ENCODING = "accept-encoding"
const

dynamic ACCEPT_LANGUAGE = "accept-language"
const

dynamic ACCEPT_RANGES = "accept-ranges"
const

dynamic AGE = "age"
const

dynamic ALLOW = "allow"
const

dynamic AUTHORIZATION = "authorization"
const

dynamic CACHE_CONTROL = "cache-control"
const

dynamic CONNECTION = "connection"
const

dynamic CONTENT_ENCODING = "content-encoding"
const

dynamic CONTENT_LANGUAGE = "content-language"
const

dynamic CONTENT_LENGTH = "content-length"
const

dynamic CONTENT_LOCATION = "content-location"
const

dynamic CONTENT_MD5 = "content-md5"
const

dynamic CONTENT_RANGE = "content-range"
const

dynamic CONTENT_TYPE = "content-type"
const

const

dynamic DATE = "date"
const

dynamic ENTITY_HEADERS = const [ALLOW, CONTENT_ENCODING, CONTENT_LANGUAGE, CONTENT_LENGTH, CONTENT_LOCATION, CONTENT_MD5, CONTENT_RANGE, CONTENT_TYPE, EXPIRES, LAST_MODIFIED]
const

dynamic ETAG = "etag"
const

dynamic EXPECT = "expect"
const

dynamic EXPIRES = "expires"
const

dynamic FROM = "from"
const

dynamic GENERAL_HEADERS = const [CACHE_CONTROL, CONNECTION, DATE, PRAGMA, TRAILER, TRANSFER_ENCODING, UPGRADE, VIA, WARNING]
const

dynamic HOST = "host"
const

dynamic IF_MATCH = "if-match"
const

dynamic IF_MODIFIED_SINCE = "if-modified-since"
const

dynamic IF_NONE_MATCH = "if-none-match"
const

dynamic IF_RANGE = "if-range"
const

dynamic IF_UNMODIFIED_SINCE = "if-unmodified-since"
const

dynamic LAST_MODIFIED = "last-modified"
const

dynamic LOCATION = "location"
const

dynamic MAX_FORWARDS = "max-forwards"
const

dynamic PRAGMA = "pragma"
const

dynamic PROXY_AUTHENTICATE = "proxy-authenticate"
const

dynamic PROXY_AUTHORIZATION = "proxy-authorization"
const

dynamic RANGE = "range"
const

dynamic REFERER = "referer"
const

dynamic REQUEST_HEADERS = const [ACCEPT, ACCEPT_CHARSET, ACCEPT_ENCODING, ACCEPT_LANGUAGE, AUTHORIZATION, EXPECT, FROM, HOST, IF_MATCH, IF_MODIFIED_SINCE, IF_NONE_MATCH, IF_RANGE, IF_UNMODIFIED_SINCE, MAX_FORWARDS, PROXY_AUTHORIZATION, RANGE, REFERER, TE, USER_AGENT]
const

dynamic RESPONSE_HEADERS = const [ACCEPT_RANGES, AGE, ETAG, LOCATION, PROXY_AUTHENTICATE, RETRY_AFTER, SERVER, VARY, WWW_AUTHENTICATE]
const

dynamic RETRY_AFTER = "retry-after"
const

dynamic SERVER = "server"
const

const

dynamic TE = "te"
const

dynamic TRAILER = "trailer"
const

dynamic TRANSFER_ENCODING = "transfer-encoding"
const

dynamic UPGRADE = "upgrade"
const

dynamic USER_AGENT = "user-agent"
const

dynamic VARY = "vary"
const

dynamic VIA = "via"
const

dynamic WARNING = "warning"
const

dynamic WWW_AUTHENTICATE = "www-authenticate"
const

Properties

chunkedTransferEncoding → bool
read / write

Gets and sets the chunked transfer encoding header value.

contentLength → int
read / write

Gets and sets the content length header value.

contentType → ContentType
read / write

Gets and sets the content type. Note that the content type in the header will only be updated if this field is set directly. Mutating the returned current value will have no effect.

date → DateTime
read / write

Gets and sets the date. The value of this property will reflect the 'date' header.

expires → DateTime
read / write

Gets and sets the expiry date. The value of this property will reflect the 'expires' header.

host → String
read / write

Gets and sets the host part of the 'host' header for the connection.

ifModifiedSince → DateTime
read / write

Gets and sets the "if-modified-since" date. The value of this property will reflect the "if-modified-since" header.

persistentConnection → bool
read / write

Gets and sets the persistent connection header value.

port → int
read / write

Gets and sets the port part of the 'host' header for the connection.

Constructors

HttpHeaders()

Operators

operator [](String name) → List<String>

Returns the list of values for the header named name. If there is no header with the provided name, null will be returned.

Methods

add(String name, Object value) → void

Adds a header value. The header named name will have the value value added to its list of values. Some headers are single valued, and for these adding a value will replace the previous value. If the value is of type DateTime a HTTP date format will be applied. If the value is a List each element of the list will be added separately. For all other types the default toString method will be used.

clear() → void

Remove all headers. Some headers have system supplied values and for these the system supplied values will still be added to the collection of values for the header.

forEach(void f(String name, List<String> values)) → void

Enumerates the headers, applying the function f to each header. The header name passed in name will be all lower case.

noFolding(String name) → void

Disables folding for the header named name when sending the HTTP header. By default, multiple header values are folded into a single header line by separating the values with commas. The 'set-cookie' header has folding disabled by default.

remove(String name, Object value) → void

Removes a specific value for a header name. Some headers have system supplied values and for these the system supplied values will still be added to the collection of values for the header.

removeAll(String name) → void

Removes all values for the specified header name. Some headers have system supplied values and for these the system supplied values will still be added to the collection of values for the header.

set(String name, Object value) → void

Sets a header. The header named name will have all its values cleared before the value value is added as its value.

value(String name) → String

Convenience method for the value for a single valued header. If there is no header with the provided name, null will be returned. If the header has more than one value an exception is thrown.