Using nested maps
You can edit some types of transforms, involving complex inputs and outputs, by entering a nested view in the Graphical Data Mapping editor.
About this task
Structural transforms control how nested elements are displayed in the Graphical Data Mapping editor. These transforms control the display of nested elements, but they do not affect the data. You can use In and Out arrow buttons and breadcrumb navigation for the nested transforms.
The following transforms can contain nested graphical data maps:
- Local map
- Join
- Append
- ForEach
- If, Else if, and Else
- Database Routine
The elements in a nested map must be mapped in order for the transform to run.
A Local map is a navigation aid that you use to view the map elements in a hierarchical way. A local map can have one primary input and multiple supplementary inputs, which can be either a simple type or a complex type. The output can be either a single element or an array element, but it must be a complex type. The local map does not transform data; you must specify transforms for the input and output elements in the nested map.
You can use the Join transform to join elements from two or more inputs. The inputs can be arrays or single elements, which can be merged using nested transforms to create a single output. The target element can be an array or single element but must be a complex type.
The Append transform iterates over multiple inputs in the specified order to append data. This transform takes multiple inputs of either simple or complex types. The output must be an array of either a simple type or a complex type.
The For each transform contains a nested map, and it iterates over one input array element (either a simple type or a complex type). The elements in the nested map must be mapped, otherwise the transform has no effect.
The If, Else if, and Else transforms enable you to control the flow of a mapping by setting conditions. If, Else if and Else operate as a group of conditional transforms, and the condition is applied to the input element of the conditional transform. If the condition is satisfied, the transform that is nested within the conditional transform is run.
The Database Routine transform contains a nested map to call a stored procedure or user-defined function from a database schema as input. Output from a Database Routine is optional, using the Return transform.
The following steps provide an example of how you can edit a nested map:
Procedure
- Some transforms, such as Local map and Append,
contain nested maps. If a nested map exists, an Edit icon
is shown on the transform. Click the Edit icon
to edit the nested map.
Nested maps must contain transforms, or else when the map is run, nothing happens. If a warning is displayed on the main map, you must edit the nested map.
- When you open a nested map for some transforms such as Append,
the nested map might also contain a nested map such as a For
each transform:
In this case, you cannot create a mapping in the first nested map. Click Edit to go down another level and you can then create your mapping, as shown:
