ATTACH statement

The ATTACH statement attaches a portion of a message tree into a new position in the message hierarchy.

Syntax

The following example illustrates how to use the ATTACH statement, together with the DETACH statement described in DETACH statement, to modify a message structure. The dynamic reference supplied to the DETACH statement must point to a modifiable message tree such as Environment, LocalEnvironment, OutputRoot, OutputExceptionList, or InputLocalEnvironment.

There are some limitations on the use of ATTACH. In general, elements detached from the output trees of a Compute node are not attached to the environment or to input trees.

For example, if you take the following message:

<Data>
  <Order>
    <Item>cheese
        <Type>stilton</Type>
    </Item>
    <Item>bread</Item>
  </Order>
  <Order>
    <Item>garlic</Item>
    <Item>wine</Item>
  </Order>
 </Data>

the following ESQL statements:

SET OutputRoot = InputRoot;
DECLARE ref1 REFERENCE TO OutputRoot.XMLNSC.Data.Order[1].Item[1];
DETACH ref1;
ATTACH ref1 TO OutputRoot.XMLNSC.Data.Order[2] AS LASTCHILD;

result in the following new message structure:

<Data>
  <Order>
     <Item>bread</Item>
  </Order>
  <Order>
     <Item>garlic</Item>
     <Item>wine</Item>
     <Item>cheese
        <Type>stilton</Type>
     </Item>
  </Order>
 </Data>

For information about dynamic references see Creating dynamic field references.