validate and transform a field value using ajv in nodejs

I want to validate and change field json_data.childOrder.Order.triggerPrice using ajv. But my customKeyword function is never called.

I want to update it to 10% of json_data.ltp

I tried to read the documentation but its not very clear how to do this. And moany examples on stackoverflow are referring to old version of ajv library.

const Ajv = require('ajv')
const ajv = new Ajv({ coerceTypes: true }) // options can be passed, e.g. {allErrors: true}

const OrderSchema = {
    type: 'object',
    properties: {
        childOrder: {
            type: 'object',
            additionalProperties: true,
            properties: {
                Order: {
                    type: 'object',

                    additionalProperties: true,

                    properties: {
                        qty: {
                            type: 'string'
                        },
                        triggerPrice: {
                            type: 'number'
                        }

                    },
                    required: ['triggerPrice', 'qty']

                }

            }
        }

    },
    additionalProperties: true

}

json_data = {
    childOrder: {
        Order: {
            buy: 'true',
            orderType: '3',
            price: 3999,
            qty: '10',
            triggerPrice: 3400
        }
    },
    duration: 'DAY',
    ltp: 3435,
    orderType: '3',
    price: 0,
    product: 'wood',
    qty: '10',
}

ajv.addKeyword({
    keyword: 'triggerPrice',
    type: 'number',
    compile: (a, b) => {
        // logic to transaform trigger price
        console.log(a, b)
    }
})
const validateOrder = ajv.compile(OrderSchema)

const _validate = validateOrder(json_data)

are there any other alternate ways of doing validatin in nodejs like there are in python marshmallow and django DRF.

In order for your custom keyword validation to work, you need to modify the compile function to return a data validation function instead of actually running validation logic:

ajv.addKeyword({
  keyword: "triggerPrice",
  type: "number",
  compile: (schema, parentSchema, it) => {
    const validate = (data, dataPath) => {
      // run your validation logic here and return true/false if data is valid
      return true;
    };
    return validate;
  },
});

In addition, in order for the keyword to be applied to a property in your schema, you need to "flag" this property with the custom keyword (having the same name doesn't do anything...): note triggerPrice: true was added to the triggerPrice property in the schema object

const OrderSchema = {
  type: "object",
  properties: {
    childOrder: {
      type: "object",
      additionalProperties: true,
      properties: {
        Order: {
          type: "object",
          additionalProperties: true,
          properties: {
            qty: {
              type: "string",
            },
            triggerPrice: {
              type: "number",
              triggerPrice: true, // add custom validation keyword
            },
          },
          required: ["triggerPrice", "qty"],
        },
      },
    },
  },
  additionalProperties: true,
};