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To merge two input fields into one output, you can select and drag one field out, then drag another input field into the same Expression field and they are combined.
To insert a new line between entries, use the unicode value of \u000A, as in: $element + "\u000A" + $element
To directly map a field from one schema to the other, click and drag the field from either schema over to the other schema, and the mapping is automatically created. You can also drag fields from the input schema to the target path.
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To search for a specific field in either the input or target schema, enter the term specific field name in the appropriate respective search field. You can use the file path wildcards * and ? in a search.
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- Select All: Click this button to select all the fields in a schema, including the collapsed children.
- Deselect All: Click this button to deselect all currently-the selected fields in a schema, including the collapsed children.
To select (or deselect) a subset of the schema, you can search for a key name first, then click Select All or Deselect All. In this case, select and deselect only apply to fields that match the search terms. - Shift-click: You can also use a keyboard shortcut to select a range of fields. Select the first field in the range, hold down the Shift key, then and select the last field in the range. You can also hold down the Shift key and click a plus symbol + in the schema hierarchy to fully expand that part of the hierarchy fully.
Watch the videos:
SelectAll.mp4
ShiftClick.mp4
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To filter whether to see all, mapped, or unmapped fields, use the drop-down next to the search field.
Additionally, once a field is mapped, it is bolded and the color is changed if you are viewing All.
If you click the mapped field in the schema, the row in the mapping table and the target are highlighted.
If an array of data is coming into the Mapper (Data) Snap, when you drag them into the table, a JSONPath expression is created to handle it.When you drag the data from the input schema into the mapping table, you can use JSONPath expressions to transform the data. 
Data Preview
By You can preview the input and target schemas by clicking the arrow under the mapping table, you can get a preview of what input and target schemas look like.
Other Usability Functions
- You can collapse the schema views using the gray arrows in the header row to give you a larger Expression and Target path columns.
- Click the down arrow within an expression field to access the expression editor, functions and properties, and the upstream schema. Click the bubble in the Target path field to access the downstream schema suggestions.
- You can rearrange the rows within the mapping table by:
- Highlighting the left side, clicking, and dragging.
- Mousing over a row until a selection arrow appears, then dragging it to a new location.
Watch the video: Move.mp4
- Highlighting the left side, clicking, and dragging.
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