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  6. InboundAttachments Annotation

@InboundAttachments Annotation

This annotation controls how the current message inbound attachments are passed into a method. The annotation supports, Map, List, single attachment, wildcards and optional entries. It can be used on component entry points and @Transformer methods.

Accessing Message Attachments

A message in Mule can optionally have attachments. THe modules in Mule that support attachments are HTTP, Email, Axis and VM. If you need to access the attachments, add a parameter to the component method signature or transformer method signature annotated with the @InboundAttachments annotation -

The '*' indicates that all headers should be returned.

@Transformer
public Person xmlToOrder(@Payload Document data,
             @InboundAttachments("*") Map<String, DataHandler> headers)

Note that the Map type will be Map<String, DataHandler>. The attahcment information can be queried from the javax.activation.DataHandler instance.

Wildcard expressions can be used to match a subset of attachments too -

@Transformer
public Person xmlToOrder(@Payload Document data,
                  @InboundAttachments("*.pdf") Map<String, DataHandler> headers)

Alternatively, you can specify a single header name and just return the value of that attachment:

public class OrderService {
   public OrderConfirmation processOrder(@Payload InputStream data,
             @InboundAttachments("shipping-info.doc") DataHandler attachment) {
         //do stuff
    }
}

To receive a subset of specific attachments, you can list them as comma-separated values:

public class OrderService {
   public OrderConfirmation processOrder(@Payload InputStream data,
         @InboundAttachments("shipping-info.doc, invoice.pdf") Map<String, DataHandler> attachments) {
         //do stuff
    }
}

By default an error will be thrown if a listed attachment is not on the response. To avoid this error, mark the header as optional with '?'. For example, shipping-info.doc is optional in the following code:

public class OrderService {
   public OrderConfirmation processOrder(@Payload InputStream data,
           @InboundAttachments("shipping-info.doc?, invoice.pdf") Map headers) {
         //do stuff
    }
}

If the return type for the @InboundAttachments param is a java.util.List, just the values will be returned.

public class OrderService {
   public OrderConfirmation processOrder(@Payload InputStream data,
        @InboundAttachments("shipping-info.doc?, invoice.pdf") List<DataHandler> attachments) {
         //do stuff
    }
}