AWS Step Function how to imitate StringStartsWith condition?

Question

I need to invoke different lambda depends on first letter of payload field. There is no appropriate Choice Rule. Is there any workaround ?

Answer 1

If you're matching on the value of the field, it's possible to use the StringMatches operator.

For instance, this should check $.some_field value and move to state Goto_A,Goto_B,Goto_C or if none match Goto_Error.

States:
  Choice_FirstLetterOfSomeField:
    Type: Choice
    Choices:
      - Variable: $.some_field
        StringMatches: 'a*'
        Next: Goto_A
      - Variable: $.some_field
        StringMatches: 'b*'
        Next: Goto_B
      - Variable: $.some_field
        StringMatches: 'c*'
        Next: Goto_C
    Default: Goto_Error