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ST - tt:ref, Current Node
Other versions: 7.31 | 7.40 | 7.54
Syntax
... [tt:]ref ...
Effect
Exactly one node of the tree structures of the current template can be set as the current node at any place within a simple transformation (statically and when the program is executed). The current node obscures the data roots in the sense that a reference name does not refer to a root name, but to the component name of the current node (see Addressing Subnodes). If the current node is defined, it is the implicit operand of many ST commands, but it can also be addressed explicitly using $ref.
This section shows how to set the current node explicitly with [tt:]ref. In addition, the statement tt:loop for transforming internal tables also sets the current node.
At positions where the current node is not set explicitly, it is undefined and cannot be addressed using $ref. In these positions, the data roots are not obscured and they can be addressed using name.
Use a command to set the current node
...
</tt:ref>
The command tt:ref sets the current node to the node specified in node. Any addressable data node can be specified for node. If no valid node is specified, the current node is undefined.
The tt:ref command can be nested. It builds a context in which the currently set node is valid. Outside the corresponding XML element, the current outermost node is still valid. On the top level, the current node is always undefined.
The command tt:ref itself has no operational effect; it only influences the impact of the commands nested within it.
Note
As a result of the addressing rules, only a subnode of the current node can be set as the new current node, unless a data root is being set.
Use an attribute to set the current node
...
</tt:...>
Many ST commands make it possible to specify the current node as the content of the attribute ref. The same rules apply to node as when setting using the command tt:ref. If no attribute ref is specified, the command applies to the current node of the context. The currently set node is valid only within the context of the ST command.
Set the current node in literal XML elements
...
</...>
In a literal XML element, tt:ref is a special attribute in the namespace of the ST command and sets the current node there. The same rules apply to node as when setting it using the command tt:ref. The currently set node is valid only within the context of the XML element.
Example
The following ST program can be used to serialize a nested ABAP structure:
xmlns:tt="http://www.sap.com/transformation-templates">
<tt:root name="ROOT"/>
<tt:template>
<X tt:ref="ROOT">
<X1>
<tt:value ref="COL1" />
</X1>
<X2>
<tt:value ref="COL2" />
</X2>
<X3 tt:ref="STRUC2">
<X1>
<tt:value ref="COL1" />
</X1>
<X2>
<tt:value ref="COL2" />
</X2>
</X3>
</X>
</tt:template>
</tt:transform>
The current node is changed as follows:
- At the beginning of the (nameless) main template, the current node is undefined. The data root ROOT can be addressed directly using "ROOT".
- The current node is set to the data root for the entire element X. Within X, only ".ROOT" could be used for addressing the data root directly.
- In the context of the two subsequent tt:value commands, the current node is set consecutively to the subnodes COL1 and COL2 of ROOT. The commands serialize or deserialize the ABAP data object that is bound to the current node.
- The current node for literal element X3, which is nested in X, is set to another subnode STRUC2 of ROOT.
- In the context of the two subsequent tt:value commands, the current node is set consecutively to the subnodes COL1 and COL2 of STRUC2. ,,Each time an element is exited, the current node is set back to that of the surrounding element.
Also see the example for calling a transformation in the tt:value, Structures section.