🚀 Express-validator

A lightweight custom validator for Express.js that supports:

• ✅ Simple rules
• ✅ Stops at the first error per field
• ✅ Works with MongoDB or MySQL
• ✅ Async database checks

📦 Installation

npm install @arweb/express-validate-rules

Validation Rules Reference

Below is the list of all supported validation rules with their usage format and behavior.

| Rule | Database | Gives error when... | Use | | ----------------- | -------- | ------------------- | --- | | required | ❌ No | Value is null or empty | { validator: "required", message: "Your message" } | | required_if | ❌ No | Field is empty when another field has a specific value | { validator: "required_if", message: "Your message", options: { other: "field_name", val: "any / or not needed" } } | | email | ❌ No | Value is not a valid email | { validator: "email", message: "Your message" } | | url | ❌ No | Value is not a valid URL | { validator: "url", message: "Your message" } | | alpha | ❌ No | Value contains non-alphabetic characters | { validator: "alpha", message: "Your message" } | | alphanumeric | ❌ No | Value contains characters other than letters or numbers | { validator: "alphanumeric", message: "Your message" } | | no_spaces | ❌ No | Value contains spaces | { validator: "no_spaces", message: "Your message" } | | no_special_chars | ❌ No | Value contains special characters | { validator: "no_special_chars", message: "Your message" } | | equal | ❌ No | Value does not equal provided string | { validator: "equal", message: "Your message", options: { allow: "Some Text" } } | | not_equal | ❌ No | Value equals the disallowed string | { validator: "not_equal", message: "Your message", options: { disallow: "Some Text" } } | | uuid | ❌ No | Value is not a valid UUID (v1–v8 or any) | { validator: "uuid", message: "Your message", options: { type: "any" } } | | slug | ❌ No | Value is not a valid slug | { validator: "slug", message: "Your message" } | | regex | ❌ No | Value does not match the pattern | { validator: "regex", message: "Your message", options: { pattern: "Pattern", flags: "Flags" } } | | contain | ❌ No | Value does not contain given element | { validator: "contain", message: "Your message", options: { element: "Some text or array" } } | | not_contain | ❌ No | Value contains disallowed element | { validator: "not_contain", message: "Your message", options: { element: "Some text or array" } } | | string_case | ❌ No | Value is not in the required case (lower/upper/title) | { validator: "string_case", message: "Your message", options: { case_type: "lower" } } | | string_length | ❌ No | String length does not meet criteria (min/max/exact) | { validator: "string_length", message: "Your message", options: { length: 3, length_type: "min" } } | | starts_with | ❌ No | Value does not start with given prefix | { validator: "starts_with", message: "Your message", options: { prefix: "Some Text" } } | | ends_with | ❌ No | Value does not end with given suffix | { validator: "ends_with", message: "Your message", options: { suffix: "Some Text" } } | | ascii | ❌ No | Value is not valid ASCII | { validator: "ascii", message: "Your message" } | | json | ❌ No | Value is not valid JSON | { validator: "json", message: "Your message" } | | array | ❌ No | Value is not a valid array | { validator: "array", message: "Your message" } | | gt | ❌ No | Value is ≤ provided val | { validator: "gt", message: "Your message", options: { val: 3 } } | | gte | ❌ No | Value is < provided val | { validator: "gte", message: "Your message", options: { val: 3 } } | | lt | ❌ No | Value is ≥ provided val | { validator: "lt", message: "Your message", options: { val: 3 } } | | lte | ❌ No | Value is > provided val | { validator: "lte", message: "Your message", options: { val: 3 } } | | number_between | ❌ No | Value is not between min and max | { validator: "number_between", message: "Your message", options: { min: 5, max: 9 } } | | integer | ❌ No | Value is not an integer | { validator: "integer", message: "Your message" } | | positive | ❌ No | Value is not positive | { validator: "positive", message: "Your message" } | | negative | ❌ No | Value is not negative | { validator: "negative", message: "Your message" } | | float | ❌ No | Value is not float/double | { validator: "float", message: "Your message" } | | numeric | ❌ No | Value is not numeric | { validator: "numeric", message: "Your message" } | | even | ❌ No | Value is not even | { validator: "even", message: "Your message" } | | odd | ❌ No | Value is not odd | { validator: "odd", message: "Your message" } | | boolean | ❌ No | Value is not a valid boolean | { validator: "boolean", message: "Your message" } | | is_true | ❌ No | Value is not true | { validator: "is_true", message: "Your message" } | | is_false | ❌ No | Value is not false | { validator: "is_false", message: "Your message" } | | file_required | ❌ No | File is missing or empty | { validator: "file_required", message: "Your message" } | | file_mime | ❌ No | File MIME type does not match | { validator: "file_mime", message: "Your message", options: { types: ["image/jpeg", "image/png"] } } | | file_storage_size | ❌ No | File size does not match rule (min/max/exact) | { validator: "file_storage_size", message: "Your message", options: { size_bytes: 100000, size_type: "max/min/exact" } } | | file_extension | ❌ No | File extension does not match allowed list | { validator: "file_extension", message: "Your message", options: { extension: [".jpg", ".png"] } } | | image_dimensions | ❌ No | Image dimensions are invalid | { validator: "image_dimensions", message: "Your message", options: { width: 200, height: 100, width_type: "max/min/exact", height_type: "max/min/exact" } } | | exists | ✅ Yes | Value does not exist in the specified database collection | { validator: "exists", message: "Your message", options: { collection: "users", field: "email", exclude: [{ field: "id", value: req.params.id, logic: "AND" }] } } Ensures the value already exists (useful for foreign key or reference checks). | | unique | ✅ Yes | Value already exists (not unique) in the specified database collection | { validator: "unique", message: "Your message", options: { collection: "users", conditions: [{ field: "username", value: req.body.username, logic: "AND" }, { field: "email", value: req.body.email, logic: "OR" }], exclude: [{ field: "id", value: req.params.id, logic: "AND" }] } } Ensures values are unique across one or more fields. Supports logical operators (AND / OR) and multiple exclusions. | | not_exists | ✅ Yes | Value already exists in the specified database collection | { validator: "not_exists", message: "Your message", options: { collection: "users", field: "email", exclude: [{ field: "id", value: req.params.id, logic: "AND" }] } } Ensures the value does not exist before inserting or updating. Commonly used for uniqueness checks during creation. |

🧠 Summary

| Rule | Validation Logic | |------|------------------| | exists | Must already exist in DB | | unique | Must be unique (not duplicated) in DB | | not_exists | Must not exist in DB at all |

✅ Notes:

• exclude supports an array of conditions with individual logic values.
• Default logic between conditions is AND if not specified.
• These database validations can be combined with non-database ones in the same validation set.

Issues

Facing bugs, please raise a Issue