Validation Utility

This validation utility provides functions to validate object fields based on rules such as min, max, pattern, and required status. It includes comprehensive error handling and field validation for string and number values.

Installation

To install this utility, you can add it to your project with npm:

npm install <package-name>

Usage

Importing the Module

After installing, you can import the validate function directly:

const validate = require('@i4nizer/obj-validator');

The validate Function

The validate function checks an object against a defined schema of fields. It verifies required fields, enforces minimum/maximum constraints, and checks pattern matching for string fields.

Function Signature

function validate(
    fields: { name: string, min?: number, max?: number, pattern?: RegExp, required?: boolean }[],
    obj: Record<string, any>
): { error: string | null, result: Record<string, any> }

Parameters

• fields: An array of field objects, each containing:

  • name (string): The field name in the object.
  • min (optional, number): Minimum length (for strings) or value (for numbers).
  • max (optional, number): Maximum length (for strings) or value (for numbers).
  • pattern (optional, RegExp): Regular expression pattern to match (for strings).
  • required (optional, boolean): Whether the field is required. If undefined, it is treated as required by default.

• obj: The object to validate, containing field values (e.g., headers, body, query, params, etc.).

Returns

The validate function returns an object with:

• error: A string containing the error message if validation fails, otherwise null.
• result: An object containing the validated fields with values from obj.

Example Usage

Here's a complete example of how to use the validate function to validate an object:

const validate = require('<package-name>');

// Define the validation schema
const fields = [
    { name: 'username', min: 3, max: 15, required: true },
    { name: 'password', min: 8, required: true },
    { name: 'age', min: 18, max: 99 },
    { name: 'email', pattern: /^[\w-.]+@([\w-]+\.)+[\w-]{2,4}$/, required: true }
];

// Object to validate
const obj = {
    username: 'john_doe',
    password: 'securepassword',
    age: 25,
    email: '[email protected]'
};

// Validate the object
const result = validate(fields, obj);

if (result.error) console.log('Validation Error:', result.error);
else console.log('Validation Successful:', result.result);

Example Output

If validation succeeds:

Validation Successful: { username: 'john_doe', password: 'securepassword', age: 25, email: '[email protected]' }

If there’s a validation error (e.g., age is less than the minimum value):

Validation Error: age must be at least 18

License

This project is licensed under the MIT License.