Setting the value of an output element by using a transform or a function

Use the Graphical Data Mapping editor to set the value of an output element by using an expression, a transform, or a function.

About this task

You can use a function or a transform to set the value of an output element, either by connecting the output element with an input element and then specifying a transform on the connection between them, or by specifying a transform directly on the output element. For information about creating connections and specifying transforms, see Editing message maps.

For information about all the functions and transforms that are available, see Transform types in the Graphical Data Mapping editor.

Transforms that support conditional control such as the If transform can use XPath 2.0 expressions, or invoke Java™ or ESQL functions.

Procedure

You can use any of the following mapping operations to map graphically your data in the Graphical Data Mapping editor

Core mapping transforms: You can use built-in structural and functional mapping operations, which enable you to graphically construct the required message transformations to build the output message. For more information, see Transform types in the Graphical Data Mapping editor.
Custom transforms: You can use custom transformations to build your own XPath 2.0, Java, or ESQL functions, which can be invoked to perform specialized transformations within the message map. For more information, see Transform types in the Graphical Data Mapping editor.
- Custom Java transform. For more information, see Custom Java.
- Custom XPath transform. For more information, see Custom XPath.
- Custom ESQL transform. For more information, see Custom ESQL.
XPath functions (fn:functionName): You can use XPath 1.0 and XPath 2.0 functions to transform data in a message map. For more information about XPath, see the online document W3C XML Path Language (XPath) 2.0.

Note: XPath 1.0 functions are valid XPath 2.0 expressions. You can use the XPath Expression Builder to generate simple XPath 1.0 expressions.
Database transforms:
- You can use the Select transform to query one or more database tables, and retrieve data that you can use in the message map to set output element values, define conditions, or use as input to build other transforms conditions. Database tables can be set as additional outputs of a message map. For more information, see Selecting data from a table.
- You can use a database routine transform to call a stored procedure or user-defined function from a database, and retrieve data that you can use in the message map to set output element values, define conditions, or use as input to build other transforms conditions.
  Note: For information about the support for stored procedures, see Support for stored procedures.

What to do next

Define transformations to set the value of output elements in your output message:

Use the Assign transform to set the value of an output element to a constant. For more information, see Setting the value of an output element to a simple data type.
Use any of the xs:type transforms to cast the value of a simple type input element and set the value of a simple type output element. For more information, see Setting the value of an output element with a explicit data type.
Use the Create transform to set the value of an output element that is defined as a simple type or as part of a complex data type. You use the default or the fixed value defined in the schema for that element. For more information, see Setting the value of a simple output element to a default or fixed value.
Use the Assign transform or the Create transform to create an empty output element defined as a string or as a hexBinary element. For more information, see Creating an empty output element.
Use the Create transform, the Move transform, the Custom Java transform, the Custom ESQL transform, or the return value of a database to create a null output element. For more information, see Creating a nil output element.
Use the fn:nilled XPath function, and the fn:exists XPath function to define conditional expressions that determine whether an input element is nilled, or is present. For more information, see Choosing an XPath conditional expression that tests for a nil value in a transform.
Use the fn:empty XPath function to define conditional expressions that determine whether an input element is empty. For more information, see Creating an empty output element.