gp-validator

A small validation library

Example usage

const { create } = require('gp-validator');
const validator = create();

const rules = {
  title: 'required',
  description: 'required',
};

const data = {
  title: '',
  descrption: ''
};

const result = validator.validate(data, rules);
// Will have an array with one string message indicating that title is required
console.log(result.errors.title);
// Will have an array with one string message indicating that description is required
console.log(result.errors.description);

Typescript

Has Typescript definitions built in so will work in a TS project too.

Rules

Built in rules are:

• required
• integer
• decimal
• money
• length

Decimal can be configured using arguments. e.g decimal(1,2) to ensure that (if a decimal point is given) then 1 to 2 digits follow it. money allows up to 2 decimal places, any more and it will be invalid.

Length can be configured using arguments. e.g length(1, 100) ensures a min length of 1 and max length of 100 characters. You can exclude either parameter to check only the min OR max, for example length(,100) ensures a max length of 100 characters.

Adding rules

Custom rules can be added

validator.addRule('fish-names', {
  rule: async (key, data) => ['cod', 'tuna', 'pike', 'trout', 'salmon'].includes(data[key]),
  errorMessage: (key, _) => `The ${key} field does not contain a valid type of fish.`,
});

const data = { fish: 'cow' };
const rules = { fish: 'fish-names' };
// Will have an array with one string message indicating that cow is not a valid fish name
const result = validator.validate(data, rules);

Change the text output when a specific rule fails

validator.setErrorHandler('required', (key, data) => `Il titolo "${data.title}" non e buona per ${key}`);

Change the error text for a particular field when a particular validation fails

    const rules = {
      title: [{
        name: 'required',
        errorMessage: (key, data) => `Il titolo "${data.title}" non e buona per ${key}`,
      }],
      description: 'required',
    }
    const result = await validator.validate(data, rules);

...mixing and matching rule definition types is ok. e.g.

    const rules = {
      title: [
        {
          name: 'decimal',
          errorMessage: (key, data) => `Il prezo "${data.price}" non e buona per ${key}`,
        },
        'required',
      ],
    };
    const result = await validator.validate(data, rules);

Nested objects are handled as follows:

    const rules = {
      nested: {
        field1: {
          field1a: 'required',
        },
      },
    };
    const data = {
      nested: {
        field1: {
          field1a: 'Hello Again',
        },
      }
    };
    const result = await validator.validate(data, rules);
    /* Returns
    {
     "nested": {
      "field1": {
       "field1a": [
        "The field1a field is required."
       ]
      },
     }
    }

Regular expressions

Change the error text for a particular field when a particular validation fails

    const result = await validator.validate(
      { toValidate: 'abc' },
      { toValidate: [
        ruleDefinitions.regex(/[0-9]/)
      ]},
    );
    // fails because 'abc' does not match the regex