Validator

A lightweight, expressive, and extensible validation library for Go — inspired by Laravel’s Validator.

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Features

• Rule-based validation like string, numeric, email, min, max, gt, lt, boolean, between etc.
• Chainable and expressive rule definitions
• Easy to extend with custom rules

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Installation

go get github.com/shivajichalise/validator

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Basic Usage

import (
    "github.com/shivajichalise/validator"
    _ "github.com/shivajichalise/validator/rules"
)

data := map[string]any{
    "username":    "rickastley",
    "email":       "rick@astley.com",
    "age":         21,
    "is_admin":    false,
    "duration":    10,
}

rules := map[string][]string{
    "username":    {"string", "min:5", "max:20"},
    "email":       {"email:rfc,dns"},
    "age":         {"numeric", "gt:18"},
    "duration":    {"between:9,11"},
}

v := validator.Make(data, rules)

if !v.Validate() {
    for field, errs := range v.Errors() {
        for _, msg := range errs {
            fmt.Printf("%s: %s\n", field, msg)
        }
    }
}

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Supported Rules

Rule	Description
string	Value must be a non-empty string
min:n	String length must be ≥ n
max:n	String length must be ≤ n
email	Validates email with basic, RFC, or DNS check
numeric	Accepts int and float
int	Value must be an integer
float64	Value must be a float64
gt:n	Value must be greater than n
lt:n	Value must be less than n
boolean	Value must be a boolean
between:min,max	Value must be between min and max

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Rule Examples

"username": {"string", "min:5", "max:20"}
"email": {"email:rfc,dns"}
"age": {"numeric", "gt:18"}
"score": {"int", "lt:100"}
"is_admin": {"boolean"}
"duration": {"between:9,11"}

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Custom Rules

Register a custom rule using:

validator.RegisterRule(MyCustomRule{})

Your rule should implement:

type Rule interface {
    Name() string
    Validate(field string, value any, params ...string) error
}

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Tests

This package is well-tested and includes:

• string, min, max
• email with basic, RFC, DNS
• numeric, int, float64
• gt, lt including type strictness and validation chaining
• Missing and invalid parameter handling
• boolean
• between

Run all tests:

go test ./...

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Contributing

We welcome contributions from the community! If you have an idea for a new feature or improvement, please submit a pull request. We also appreciate bug reports and other feedback.

To get started with contributing, simply fork this repository, make your changes, and submit a pull request.

License

This project is licensed under MIT

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