How to use the not function from joi

joi.not is a method in the Joi validation library that negates a given validation schema.

How does joi.not work?

joi.not is a method in the Joi validation library that negates a given validation schema. When you call joi.not(), you pass in a Joi schema as its parameter. The method returns a new schema that negates the original schema, meaning that it will validate values that do not match the original schema. For example, if you have a schema that validates strings that contain only letters, you can use joi.not() to create a new schema that validates strings that contain anything other than letters. The joi.not() method can be used in conjunction with other Joi validation methods to create more complex validation schemas. For example, you could use joi.object() to define an object schema and then use joi.not() to negate a particular property validation. Overall, joi.not() provides a way to negate a validation schema and create more flexible validation rules for your application's data.

Ai Example

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const Joi = require("joi");

const schema = Joi.object({
  name: Joi.string().required(),
  age: Joi.number().positive().required(),
});

const negatedSchema = Joi.object({
  name: Joi.not(Joi.string().required()),
  age: Joi.not(Joi.number().positive().required()),
});

const user = {
  name: 123,
  age: -10,
};

const result1 = schema.validate(user);
console.log(result1.error); // Output: ValidationError: "name" must be a string

const result2 = negatedSchema.validate(user);
console.log(result2.error); // Output: undefined

In this example, we first define a schema using Joi.object() that requires a name property that is a string and an age property that is a positive number. We then define a second schema using Joi.object() that negates the name and age properties of the original schema using Joi.not(). This means that the negated schema will validate objects where the name property is not a string and the age property is not a positive number. Next, we define a user object that fails the validation of the original schema since the name property is a number and the age property is negative. We then validate the user object against both schemas using the validate() method. The first schema validation will return an error because the name property is not a string, but the second schema validation will pass because the name and age properties do not match the negated schema. Overall, this example demonstrates how to use joi.not() to negate a validation schema and create more flexible validation rules for your application's data.