if string is empty or null or "", then i need to set default value in enum using json schema validation

there are 2 problems:

• string is with small s
  • Error: schema is invalid...
  • https://ajv.js.org/json-schema.html#keywords-for-strings
  • type: "string"
• you must set your validation lib properly
  • https://ajv.js.org/options.html#usedefaults
  • new Ajv({ useDefaults: 'empty' })

import Ajv from "ajv" const schema = { type: 'object', properties: { BankAccount: { type: 'string', // string with small s enum: ['Y', 'N'], default: 'N' } } }; const ajv = new Ajv({ useDefaults: 'empty' // treat "" and null as “missing” }); const validate = ajv.compile(schema); const data1 = {}; // BankAccount missing const data2 = { BankAccount: '' }; // empty string const data3 = { BankAccount: null }; // null const data4 = { BankAccount: 'Y' }; // valid value const data5 = { BankAccount: 'N' }; // valid value [ data1, data2, data3, data4, data5 ].forEach((d, i) => { validate(d); // mutates d in‑place console.log(`data${i+1}:`, d); }); // data1: { BankAccount: 'N' } // data2: { BankAccount: 'N' } // data3: { BankAccount: 'N' } // data4: { BankAccount: 'Y' } // data5: { BankAccount: 'N' }