Remove columns from Excel files using the Mapper Snap

This example demonstrates how to use the Mapper Snap to remove specific columns from an Excel file.

Configure the File Reader Snap
Use the File Reader Snap to read the Excel file from SLDB that contains the columns you want to remove.
Parse the file using the Excel Parser Snap
Add the Excel Parser Snap to parse the Excel data. Preview the parsed data using the SL-data-preview icon to identify the unnecessary columns.
Add a Mapper Snap to the pipeline
Use the Mapper Snap to remove the unwanted columns from the dataset. For this example, remove the Discounts and Month Number columns.
Configure the Mapper Snap
In the Expression field, enter the following expression:
```
$.filter((value, key) => !key.match("Discounts|Month Number"))
```
Set the Target field to $ to preserve all other column names.

Validate the pipeline to confirm that the specified columns are removed.
Add a JSON Formatter Snap
Use the JSON Formatter Snap to convert the output documents from the Mapper Snap into JSON format.
Write the updated data using the File Writer Snap
Use the File Writer Snap to write the final output into the SLDB as a JSON file.

You can now view the updated file in the destination project in SnapLogic® Manager. The file excludes the Discounts and Month Number columns.