Karate's set via table approach for payload building: https://github.com/intuit/karate#set-multiple

multi-set.feature

Scenario: set via table where variable does not exist
    note how karate will create parent paths if needed

    * set foo
    | path | value      |
    | bar  | 'baz'      |
    | a.b  | 'c'        |
    | fizz | { d: 'e' } |
    
    * match foo == { bar: 'baz', a: { b: 'c' }, fizz: { d: 'e' } }

Scenario: set via table with fancy array paths and multi-dimensional arrays

    * set foo
    | path   | value   |
    | bar[0] | 'baz'   |
    | a[0].b | 'ban'   |
    | c[0]   | [1, 2]  | 
    | c[1]   | [3, 4]  |
    
    * match foo == { bar: [ 'baz'], a: [{ b: 'ban' }], c: [[1, 2], [3, 4]] }

Scenario: set via table, and blanks are skipped

   * set search
        | path       | 0        | 1      | 2       |
        | name.first | 'John'   | 'Jane' |         |
        | name.last  | 'Smith'  | 'Doe'  | 'Waldo' |
        | age        | 20       |        |         |

    * match search[0] == { name: { first: 'John', last: 'Smith' }, age: 20 }
    * match search[1] == { name: { first: 'Jane', last: 'Doe' } }
    * match search[2] == { name: { last: 'Waldo' } }