assign.ts

import { createMachine, assign } from "xstate";

type Context = {
  groups: number[],
  group: number
}

type Event =
  | { type: "SELECT_OFFER_GROUP"; data: number }
  | { type: "SET_GROUPS"; data: number[] };

const m = createMachine<Context, Event>(
  { initial: "start" },
  {
    actions: {
      /**
        setGroups error: 
       
        Types of parameters 'event' and 'event' are incompatible.
        Type 'Event' is not assignable to type '{ type: "SET_GROUPS"; data: number[]; }'.
        Type '{ type: "SELECT_OFFER_GROUP"; data: number; }' is not assignable to type '{ type: "SET_GROUPS"; data: number[]; }'
       */
      'setGroups': assign<Context, { type: "SET_GROUPS"; data: number[] }>({
        groups: (c, e) => e.data
      }),
      'selectGroup': assign({
        /**
         e.data is (property) data: number | number[]
         */
        group: (_, e) => e.data
      })

    }
  }
)