In the Data Mapper tab
of the Mapping perspective, right-click Maps in Hierarchical
Mapper and click New > Map.
In the wizard that opens, select DSQL Map and click
Next.
Select a folder and enter a name for the map, then click
Finish.
The name must be unique across all maps.
The map opens in the editor, you can now add the structures.
Place the input structure from the Hierarchical
Mapper on the left section of the editor and the output structure on
the right section.
If your structures have multiple representations, you can click the name of the
representation at the top of the editor, JSON in this example,
and select another one. For more information, see Adding a representation to a structure.
A first mapping between the root elements is automatically created. You
can see the corresponding Data Shaping Query Language expression in the root element of the output structure.
Right-click the input root element, bikesandscoots in this
example, and click Expand all to display all the elements
in the structure.
Place the input make element on the output make
element.
Information noteTip: You can place the input element on the corresponding element in the
output structure, but you can also place it in the output element's expression
editor under the map.
You can see that the input categories and
items elements are connected to the output items
element. If you click the output items, you can see that the
following expression was generated automatically:
FROM categories
UNNEST items
This expression means that the map should produce one output
items element for each items element in each
categories element in the input. In the input file used in
this example, there are two categories that contain three
items each, so the output would contain six
items elements.
In the output items element, under the existing expression,
add the following clause to filter the output and only keep records related to
bicycles.
WHERE category = 'bicycles'
Now that the input category element is included in the
query, it is connected to the output items element.
Place the input description element on the corresponding output
element.
Click the output price element and enter the following
expression to format the output:
concat(price,' USD')
Results
Your map is configured, you can use the Test Run feature to
test it.
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