Fields Mapping can be done at the Vertical Level.
To manage fields mapping, Go to Settings -> Verticals and click on the Vertical Name to open the vertical window.
From the Verticals Menu, Click on Fields
Click on the Icon Field Mapping 
Click Add Mapping Value... to add new mapping value.
Field Value: Type the value you want to map.
Mapping Value: Type the Mapping Value
Condition: Select Exact Match to Map True to 1 or Replace to map every occurrence of true within a string to 1.
Click Save and Close.