Specifying a transform (mapping operation)

Specify a transform, a cast function, or an XPath function between two or more elements by selecting from the list of available mapping operations that are shown on the connection.

Learn about the different mapping operations. For more information, see Transforms (Mapping operations).

In the Graphical Data Mapping editor, you can use transforms, cast functions, and XPath 2.0 functions to run different actions on input data and move the result to the output element. You choose the appropriate mapping operation that is based on the result that you want to achieve.

When you create a connection between two or more elements, a transform is assigned, based on the number and type of input elements. You can then change the transform by choosing from a list of available transforms. If a particular transform type is not shown in the list, that transform is not valid for your input and output elements.

For example:

A simple map between two elements

Note: Transforms that require multiple inputs such as ForEach, Join, or Append are not available in the list of available transforms until you wire two inputs to the transform.

Note: When you drag and drop a connection from an input element to an output element, a transform is added automatically. To add the transform, you must drop the connection above the lowest point of the input and output message. If you use this method in a nested map, you must drop the connection above the bottom of the shaded area.

When you have a list of valid transform types, choose the appropriate transform:

If you have a single array as input, with the same array type as output, and you want to move all elements to the output, use Move.
If you have a single array as input, and you want to iterate over each element in the array (for example, you might want to remove some elements) use the ForEach transform and set the cardinality options.
If you have multiple input elements, you can use the Append or the Join transforms. If you use the Append transform, the number of output elements is the total of the input elements. If you use Join transform, the number of output elements depends on the user expression added to specify the matching criteria for joining or filtering input items.

The following steps show how to change the transform that is selected, and also how to add more elements:

Change the transform by clicking the arrow in the transform box, and selecting from the list of available transforms. For example:
If you create more primary connections between an input element and the transform, the transform type changes to one that allows multiple primary inputs, such as Local Map, Concat, or Join. For example:

Configure the properties of the transform. For more information, see Configuring the properties of a transform.

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