matlab.net.http.io.FormProvider Class
Namespace: matlab.net.http.io
Superclasses: matlab.net.http.io.StringProvider
ContentProvider that sends form data
Description
This provider creates data suitable for a request message whose Content-Type is
"application/x-www-form-urlencoded"
, as required by many servers that
expect users to fill in HTML forms.
Using this provider in the Body
of a RequestMessage
is
optional, because you can insert a QueryParameter
vector directly into the
Body
of a RequestMessage
to get the same conversion done
automatically.
Subclass authors can create a FormProvider
subclass to create the data
dynamically only when the message is ready to be transmitted, or during transmission.
The matlab.net.http.io.FormProvider
class is a handle
class.
Creation
Description
provider = FormProvider(
constructs
a provider that sends a vector of queryparams
)QueryParameter
objects specified as
queryparams
. This constructor sets the
Parameters
property to the value of
queryparams
.
provider = FormProvider(
sends an
arbitrary list of arguments to the arg1,...,argn
)matlab.net.QueryParameter
constructor to
obtain a QueryParameter
vector. This syntax a shortcut for:
FormProvider(QueryParameter(arg1,...,argn))
Input Arguments
arg1,...,argn
— QueryParameter
constructor arguments
valid types
One or more input arguments to the matlab.net.QueryParameter
constructor, specified as valid argument types. If your arguments are already encoded,
append a 'literal'
argument to the end of the list.
Properties
Public Properties
Parameters
— Query parameters
vector or cell array of matlab.net.QueryParameter
Query parameters, specified as a vector or cell array of matlab.net.QueryParameter
objects as
passed into or derived from the arguments to the constructor. To see the body of the
message, use the string
method.
Attributes:
GetAccess | public |
SetAccess | public |
Dependent | true |
Header
— Header fields of message or part
matlab.net.http.HeaderField.empty
(default) | matlab.net.http.HeaderField
Header fields of the message or part, specified as a vector of one or more
matlab.net.http.HeaderField
objects.
This property is only used by subclass authors. MATLAB® sets this property before calling the provider's complete
method. For non-multipart messages, MATLAB initializes this property to the contents of
Request.Header
, minus any matlab.net.http.field.GenericFields
or
empty-valued fields. The ContentProvider
uses this property to add header
fields that describe the data to be sent, or to add parameters to header fields already
in the message. In a delegate for a MultipartProvider
, MATLAB initializes this property to header fields that the delegating provider
intends to insert for the part. Delegates can modify or change these fields.
Upon return from the provider's complete
method, if this not a
multipart message, then MATLAB reads this property and merges its contents into the header of
Request
. Fields in this Header
with
Names
that do not already appear in
Request.Header
are added to the end of
Request.Header
. If a field in this Header
has a Name
that is the same as one in
Request.Header
, and both have nonempty
Values
, then:
If the one in
Request.Header
is aGenericField
, then ignore the one inHeader
.If the one in
Request.Header
is not aGenericField
, then replace it with the one inHeader
.
If one or both of these has an empty Value
, then the field is
removed from Request.Header
and it is not added as part of normal
message completion.
If this is a delegate of a MultipartProvider
, then the entire contents
of this Header
is used as the header of the part. Multipart
delegates must not assume that Request.Header
contains any fields
pertaining to their own Header
. A provider can determine whether it
is a multipart delegate by checking whether MyDelegator
is a
MultipartProvider
, though this test is unlikely to be needed.
MATLAB reads this property only on return from calling the provider's
complete
method. Changes to this array are ignored once MATLAB calls start
.
Class authors should be aware that their subclasses might have added fields to this
Header
(in their complete
method) before
calling complete
in their superclass. It is best to preserve such
fields and not to add fields with the same names. However, adding a parameter to a field
is permissible. For example, a superclass can add a charset parameter to an existing
Content-Type field that does not already have one.
Attributes:
GetAccess | public |
SetAccess | public |
ForceChunked
— Indicate whether to force chunked transfer coding
false
(default) | true
Indicate whether to force chunked transfer coding, specified as boolean. This property is of interest only to subclass authors, and is applicable only to providers that are not multipart delegates. Subclasses set ForceChunked
to control whether contents should be sent using chunked transfer coding. If false
(default), MATLAB decides whether to send the contents chunked, based on whether it knows the content length at the time the message is ready to be sent:
If MATLAB knows the content length (which is the case if the message contains a Content-Length field, or if this provider's
expectedContentLength
method returned a number), then MATLAB decides whether to send it chunked or not.If MATLAB does not know the content length (no Content-Length field in the header and
expectedContentLength
returned empty), then MATLAB always sends the message chunked.
If ForceChunked
is true
, then MATLAB sends the message chunked regardless of whether it knows the content length, unless the known length is smaller than the chunk size. If this property is true
, then the message must not contain a Content-Length field, because HTTP does not allow a chunked message to have a Content-Length field. However, you can still return a nonzero value in the expectedContentLength
method if you want MATLAB to verify that you are returning the expected length of data.
When MATLAB chooses to send the message chunked, the size of each chunk is equal to the length of data returned by getData
.
MATLAB reads this value after calling the complete
method, before calling start
. It does not set this field.
Attributes:
GetAccess | public |
SetAccess | public |
Request
— Request message to send
matlab.net.http.RequestMessage
Request message to send, specified as a matlab.net.http.RequestMessage
object.
This property is used only by subclass authors. The
RequestMessage.send
and RequestMessage.complete
methods set this property to the RequestMessage
in whose
Body
this provider has been placed, before calling any other
methods in this provider, and before adding any additional header fields or validating
the message. The provider can examine this message to see what was contained in the
original request.
Delegates see the same value for this property as the delegator.
ContentProviders
should be aware that, if they are delegates, they
are not necessarily providing the entire body of the request message, so they should not
assume that header fields in this Request are pertinent to the data they are providing.
Usually, delegates should ignore header fields in this request relevant to the data,
such as Content-Type.
If the provider wishes to add any header fields to this message, or to modify existing
ones, it should do so in its complete
method by adding those fields to the Header
property. The caller of
complete
(RequestMessage
or a delegating provider)
determines what to do with those fields. RequestMessage.send
and
RequestMessage.complete
always copy these fields to the
Header
of the RequestMessage
. A delegating
provider can copy the fields to its own Header
property or insert
them into the message (as in the case of MultipartProvider
). For more
information, see the Header property.
This property is read-only.
Attributes:
GetAccess | public |
SetAccess | matlab.net.http.RequestMessage |
Protected Properties
CurrentDelegate
— ContentProvider
to which this provider is delegating
matlab.net.http.io.ContentProvider
| empty
ContentProvider
to which this provider is delegating, specified as a matlab.net.http.io.ContentProvider
object. This property is set in the calling provider (the delegator) by the delegateTo
method to indicate the current delegated provider. If there is no current delegation, then the value is empty.
The complete
methods set this property to empty.
Attributes:
GetAccess | protected |
SetAccess | protected |
MyDelegator
— ContentProvider
that delegated to this provider
matlab.net.http.io.ContentProvider.empty
(default) | matlab.net.http.io.ContentProvider
ContentProvider
that delegated to this provider, specified as a matlab.net.http.io.ContentProvider
object.
If a ContentProvider
delegates responsibility for sending all or a portion of the message data to another provider, then this property identifies the delegating provider to the delegate. For example, a MultipartProvider
delegates parts of the message to other providers, so it inserts a handle to itself in each delegate. Otherwise, MyDelegator
is empty. The delegateTo
method sets this property in the delegate.
Attributes:
GetAccess | protected |
SetAccess | protected |
Methods
Public Methods
getData | Next buffer of data to send in HTTP request message from StringProvider |
Specialized Operators and Functions
These methods specialize standard MATLAB operators and functions and inherited methods for objects in this class.
string |
|
show | Display |
Protected Methods
complete | Complete HTTP header for StringProvider |
preferredBufferSize | Preferred buffer size for ContentProvider |
expectedContentLength | Content length of ContentProvider |
start | Start data transfer from ContentProvider |
restartable | Indicate whether ContentProvider is restartable |
reusable | Indicate whether ContentProvider is reusable |
delegateTo | Delegate to another provider |
More About
Class Hierarchy
Version History
Introduced in R2018a
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