I have two fields a and b in my model schema;

let list = require("../helpers/data.json"); 

const schema = new mongoose.Schema({
   a: String,
   b: {
      type: String,
      get: (val) => {
            return statesList.find((s) => s.code == val && s.second_code == this.a);
      },

   },

})

in my getter how can i get (use/access) the value of the field a