Available Validators

This package includes several predefined validators:

Blank: Ensures the value is blank ("" or nil).
NotBlank: Ensures the value is not blank.
Nil: Ensures the value is nil.
NotNil: Ensures the value is not nil.
IsTrue: Ensures the value is true.
IsString: Ensures the value is string.
IsFloat: Ensures the value is float.
IsFloat32: Ensures the value is float32.
IsFloat64: Ensures the value is float64.
IsInt: Ensures the value is int.
IsInt8: Ensures the value is int8.
IsInt16: Ensures the value is int16.
IsInt32: Ensures the value is int32.
IsInt64: Ensures the value is int64.
IsUint: Ensures the value is uint.
IsUint8: Ensures the value is uint8.
IsUint16: Ensures the value is uint16.
IsUint32: Ensures the value is uint32.
IsUint64: Ensures the value is uint64.
IsStruct: Ensures the value is struct.
IsFalse: Ensures the value is false.
IsBool: Ensures the value is a boolean (true or false).
Struct: Ensures the value is struct of type ``. (Example)
Currency: Ensures the value is a valid currency code.
Email: Ensures the value is a valid email address.
Language: Ensures the value is a valid language code without a region (e.g., en).
LanguageWithRegion: Ensures the value is a valid language code with a region (e.g., en-US).
Range: Ensures the value is within a defined range (e.g., a number between min and max). It support int and float. (Example)
ArrayRange: Ensures the value is within a defined array range (e.g., a number between min and max). It support int and float. (Example)
EqualTo: Ensures the value is equal to.
GreaterOrEqual: Ensures the value is greater or equal. (support int, float)
GreaterThen: Ensures the value is greater. (support int, float)
LessOrEqual: Ensures the value is less or equal. (support int, float)
LessThen: Ensures the value is less then. (support int, float)
IsEven: Ensures the value is an even integer.
IsOdd: Ensures the value is an odd integer.
IsMultipleOf: Ensures the value is a multiple of a specif
Options: Ensures the value is within a defined array. (Example)
ArrayOptions: Ensures the values (array) is within a defined array. (Example)
Required: Ensures the value is not blank or nil.
RegularExpression: Ensures the value match regular expression. (Example)
Date: Ensures the value is valid date. (Example)
Url: Ensures the value is valid url. (Example)
PhoneNumber: Ensures the value is valid phone number (with option format). (Example)
Length: Ensure the value has length. (Example)
Field: Allow you to validate nested structures, such as map[string]any, where each field can have its own constraints. (Example)
Composite: Allow you to combine multiple constraints into one, symplifying validation logic when a single field needs to meet multiple criteria. (Example)
Country: Ensures the value is valid (one of name, alpha-2 (2 letters code), alpha-3 (3 letters code)) by ISO 3166-1.
IsIPv4: Ensures the value is IP4 address.
IsIPv6: Ensures the value is IP6 address.
IsMAC: Ensures the value is MAC address.
IsLowercase: Ensures the value is entirely lowercase.
IsUppercase: Ensures the value is entirely uppercase.
IsTitleCase: Ensures the value starts with an uppercase letter.
IsCamelCase: Ensures the value follows camelCase format.
IsPascalCase: Ensures the value follows PascalCase format.
HasPrefix: Ensures the value starts with a specified prefix.
HasSuffix: Ensures the value ends with a specified suffix.
Contains: Ensures the value contains a specified substring.
IsBase32: Ensures the value is a valid Base32-encoded string.
IsBase64: Ensures the value is a valid Base64-encoded string.
IsSHA256: Ensures the value is a valid SHA-256 hash (64 hex characters).
IsHexColor: Ensures the value is a valid hex color (e.g. #fff or #ffffff).
IsHSLColor: Ensures the value is a valid HSL/HSLA color.
IsRGBColor: Ensures the value is a valid RGB/RGBA color.
IsHex: Ensures the value is a valid hexadecimal string.
IsJSON: Ensures the value is a valid JSON string.
IsJWT: Ensures the value is a valid JWT token (three base64 segments).
IsUUIDv1: Ensures the value is a valid UUID version 1.
IsUUIDv3: Ensures the value is a valid UUID version 3.
IsUUIDv4: Ensures the value is a valid UUID version 4.
IsUUIDv5: Ensures the value is a valid UUID version 5.
IsUUID: Ensures the value is a valid UUID (optionally of a specific version).
Custom: Custom constraint with user-defined validation logic (Example).

Examples

Struct

con := constraints.Struct{
		Struct: MyStruct{},
	}

errs := validator.Validate(value, con)

RegularExpression

regExp := `^[a-z]{3}$`
con := constraints.RegularExpression{
    Regexp: regExp,
}

errs := validator.Validate(value, con)

Range

con := constrains.Range{
	Min: 5,
	Max: 20,
}

value := 7

errs := validator.Validate(value, con)

ArrayRange

con := constrains.ArrayRange{
	Min: 5,
	Max: 20,
}

value := []any{5, 15, 19}

errs := validator.Validate(value, con)

Options

con := constraints.Options{
		Options: []any{"option1", "option2", "option3", 42},
	}

value := "option1"

errs := validator.Validate(value, con)

ArrayOptions

con := constraints.ArrayOptions{
		Options: []any{"Red", "Green", "Blue", 100},
	}
	
values := []any{"Red", "Green", 100}
errs := validator.Validate(values, con)

Date

dateFormat := "2006-01-02"
minDate, _ := time.Parse(dateFormat, "2023-01-01")
maxDate, _ := time.Parse(dateFormat, "2023-12-31")

con := constraints.Date{
    Min:    minDate,
    Max:    maxDate,
    Format: dateFormat,
}

value := "01-05-2023"
errs := validator.Validate(value, con)

Url

v := constraints.Url{
    AllowEmpty:     false,
    AllowedSchemes: []string{"http", "https"},
}

value := "https://example.com"
errs := validator.Validate(value, v)

Length

Map

v := constraints.Length{
    Max: 4,
}

value := map[string]int{"a": 1, "b": 2, "c": 3}
errs := validator.Validate(value, v)

String

v := constraints.Length{
    Max: 4,
}

value := "hello"
errs := validator.Validate(value, v)

### Phone number

```go
v := constraints.PhoneNumber{Format: "(00420) 000 000 000"}

value := "(00420) 123 456 789"
errs := validator.Validate(value, v)

Field

nestedValidator := constraints.Field{
    Constraints: map[string]validator.Constraint{
        "Name":  constraints.NotBlank{},
        "Email": constraints.Email{},
        "Address": constraints.Field{
            Constraints: map[string]validator.Constraint{
                "City":    constraints.NotBlank{},
                "Country": constraints.NotBlank{},
            },
        },
    },
}

errs := validator.Validate(value, nestedValidator)

Composite

nestedValidator := constraints.Field{
    Constraints: map[string]validator.Constraint{
        "Email": constraints.Composite{
            Constraints: []validator.Constraint{
                constraints.NotBlank{},
                constraints.Length{Min: 5, Max: 50},
                constraints.Email{},
            },
        },
        "Name": constraints.Composite{
            Constraints: []validator.Constraint{
                constraints.NotBlank{},
                constraints.Length{Min: 3, Max: 100},
            },
        },
    },
}

errs := validator.Validate(value, nestedValidator)

Custom

con := constraints.Custom{
	Fn: func(value any) error {
		s, ok := value.(string)
		if !ok {
			return errors.New("value must be a string")
		}
		if len(s) < 5 {
			return errors.New("string must be at least 5 characters long")
		}
		return nil
	},
}

value := "abc"

errs := validator.Validate(value, con)

if len(errs) > 0 {
	for _, err := range errs {
		fmt.Println("Validation error:", err)
	}
}

Custom Validator

If you want to add your own validator, simply implement the Constraint interface and write the Validate method to perform the validation.

package constraints

import "errors"

type GreaterThan100 struct{}

func (c GreaterThan100) Validate(value any) error {
	num, ok := value.(int)
	if !ok {
		return errors.New("this value must be an integer")
	}
	if num <= 100 {
		return errors.New("this value must be greater than 100")
	}
	return nil
}

Packages

Available Validators

Examples

Struct

RegularExpression

Range

ArrayRange

Options

ArrayOptions

Date

Url

Length

Map

String

Field

Composite

Custom

Custom Validator