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.
Drag and drop 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.
Drag and drop the input make element on the output
make element.
Information noteTip: You can drop the input element on the corresponding element in
the output structure, but you can also drop 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.
Drag and drop 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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