Validating data with Joi can result in multiple error messages being displayed for a single field

Question

Validating data with Joi can result in multiple error messages being displayed for a single field

I'm attempting to implement a validation flow using the joi package, which can be found at https://www.npmjs.com/package/joi.

1) First, I want to check if the field category exists. If it doesn't, I should display the error message category required.

2) Next, I need to verify that the category field only allows alphabetic characters. If it contains any other characters, I should show the error message provide valid category

Below is my code snippet:

const schema = Joi.object().keys({
    category: Joi.string().required().error(new Error('category is required')),
    category: Joi.string().regex(/^[a-zA-Z]*$/).required().error(new Error('category is not valid')),
});

Unfortunately, the code did not work as expected.

javascript validation express joi

Answer 1

Answer №1

If you want to identify the cause of an error, you can pass a callback function to the error() method.

Your custom callback could be structured as follows:

const onError = x => {
    switch (x[0].type) {
        case 'any.required': {
            return new Error('category is required');
        }
        case 'string.regex.base': {
            return new Error('category is not valid');
        }
        default: {
            return new Error('category has some error');
        }
    }
};

After defining your callback function, you can integrate it like this:

category: Joi.string()
                .regex(/^[a-zA-Z]*$/)
                .required()
                .error(onError)

Below is the entire code snippet that demonstrates the usage:

const Joi = require('joi');

const onError = x => {
    switch (x[0].type) {
        case 'any.required': {
            return new Error('category is required');
        }
        case 'string.regex.base': {
            return new Error('category is not valid');
        }
        default: {
            return new Error('category has some error');
        }
    }
};

const schema = Joi.object().keys({
    category: Joi.string()
                .regex(/^[a-zA-Z]*$/)
                .required()
                .error(onError)
});

const testCategories = [{ category: 'ABCD' }, {}, { category: '&&&' }];

testCategories.forEach(aCategory => {
    schema
        .validate(aCategory)
        .then(() => {
            console.log(JSON.stringify(aCategory), 'passed!');
        })
        .catch(e => {
            console.log(JSON.stringify(aCategory), 'failed', e);
        });
});

Answer 2

If you want to identify the cause of an error, you can pass a callback function to the error() method.

Your custom callback could be structured as follows:

const onError = x => {
    switch (x[0].type) {
        case 'any.required': {
            return new Error('category is required');
        }
        case 'string.regex.base': {
            return new Error('category is not valid');
        }
        default: {
            return new Error('category has some error');
        }
    }
};

After defining your callback function, you can integrate it like this:

category: Joi.string()
                .regex(/^[a-zA-Z]*$/)
                .required()
                .error(onError)

Below is the entire code snippet that demonstrates the usage:

const Joi = require('joi');

const onError = x => {
    switch (x[0].type) {
        case 'any.required': {
            return new Error('category is required');
        }
        case 'string.regex.base': {
            return new Error('category is not valid');
        }
        default: {
            return new Error('category has some error');
        }
    }
};

const schema = Joi.object().keys({
    category: Joi.string()
                .regex(/^[a-zA-Z]*$/)
                .required()
                .error(onError)
});

const testCategories = [{ category: 'ABCD' }, {}, { category: '&&&' }];

testCategories.forEach(aCategory => {
    schema
        .validate(aCategory)
        .then(() => {
            console.log(JSON.stringify(aCategory), 'passed!');
        })
        .catch(e => {
            console.log(JSON.stringify(aCategory), 'failed', e);
        });
});

Validating data with Joi can result in multiple error messages being displayed for a single field

Answer №1

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