Manipulating attachments in a message object

The message object provides APIs and properties to manipulate message attachments.

If the assembly includes a parse policy, attachments in the request or response of a multipart message can be manipulated and sent back to the client. By default, the response is sent to the client in multipart format.

Restriction: You cannot add an attachment to a request or response which does not contain existing attachments.

Alternatively, you can clear context.message.attachments to discard the attachments and send only message.body to the client.

Note: If the assembly does not include a parse policy, the following processing rules apply.

For a multipart request where the message.body variable is not changed, the invoke policy keeps and passes the attachments to the server.
For a multipart request or response where the message.body variable is not changed, the result API action passes the attachments as the final response.
If the message.body variable is changed, attachments are discarded.

Retrieving an attachment
Appending an attachment to the message
Retrieving the number of attachments in an array
Removing an attachment from the message
Reading, accessing, and manipulating the body of an attachment
Manipulating the headers of an attachment

Retrieving an attachment

GatewayScript examples

Retrieve the attachment by index location.

context.message.attachments[1]

Retrieve the attachment by looking up the value of pic1 in the Content-Id header.

context.message.attachments['cid:pic1']

Retrieve the attachment by looking up the value of uri1 in the Content-Location header.

context.message.attachments['uri1']

Appending an attachment to the message

GatewayScript example

var headers = JSON.parse ( '{ "Content-Type": "text/xml; charset=utf-8", "Content-Id": "<data>" }' );
context.message.attachments.append(headers, 'Hello world.');

Retrieving the number of attachments in an array

Example

for (var i = 0; i < context.message.attachments.count; i++) {
  context.message.attachments[i].header.set('X-Foo', 'bar');
}

Removing an attachment from the message

GatewayScript examples

Remove the attachment by index location.

context.message.attachments.remove(1)

Remove the attachment by looking up the value of pic1 in the Content-Id header.

context.message.attachments.remove('cid:pic1')

Remove the attachment by looking up the value of uri1 in the Content-Location header.

context.message.attachments.remove('uri1')

Reading, accessing, and manipulating the body of an attachment

GatewayScript examples

To read the payload of an attachment in binary and return the contents as either a Buffer, Buffers, JSON, or

XML
NodeList

object:

context.message.attachments[0].body.readAsBuffer(function(errorObject,bufferObject){})
context.message.attachments[0].body.readAsBuffers(function(errorObject,buffersObject){})
context.message.attachments[0].body.readAsJSON(function(errorObject,jsonObject){})
context.message.attachments[0].body.readAsXML(function(errorObject,nodeList){})

To write content Hello world to the current payload of the attachment:

message.attachments[0].body.write("Hello world")

Manipulating the headers of an attachment

GatewayScript examples

To retrieve the values of the whole attachment headers:

context.message.attachments[0].headers

To retrieve the value of the named header of the attachment:

context.message.attachments[0].header.get();

To delete the current Content-Type header of the attachment.

context.message.attachments[0].header.remove('Content-Type');

You can set the value of the named header of an attachment. The header can be coalesced and noncoalesced. Take the following code as an example.

context.message.attachments[0].header.set('MyCookie', ['cookie1', 'cookie2']);

If the value type is array, the MyCookie header is noncoalesced and it is present with different entries in HTTP header.

MyCookie: cookie1
MyCookie: cookie2