govalid

Struct validation using tags

Programming language: Go

License: MIT License

Tags: Validation    

Latest version: v1.2.0

README

Govalid

Use Govalid to validate structs.

Documentation

For full documentation see pkg.go.dev.

Example

package main

import (
    "fmt"
    "log"
    "strings"

    "github.com/twharmon/govalid"
)

type Post struct {
    // ID has no constraints
    ID int

    // Title is required, must be at least 3 characters long, cannot be
    // more than 20 characters long, and must match ^[a-zA-Z ]+$
    Title string `govalid:"req|min:3|max:20|regex:^[a-zA-Z ]+$"`

    // Body is not required, cannot be more than 10000 charachers,
    // and must be "fun" (a custom rule defined below).
    Body string `govalid:"max:10000|fun"`

    // Category is not required, but if not zero value ("") it must be
    // either "announcement" or "bookreview".
    Category string `govalid:"in:announcement,bookreview"`
}

var v = govalid.New()

func main() {
    // Add Custom validation to the struct `Post`
    v.AddCustom(Post{}, func(val interface{}) string {
        post := val.(*Post)
        if post.Category != "" && !strings.Contains(post.Body, post.Category) {
            return fmt.Sprintf("Body must contain %s", post.Category)
        }
        return ""
    })

    // Add custom string "fun" that can be used on any string field
    // in any struct.
    v.AddCustomStringRule("fun", func(field string, value string) string {
        if float64(strings.Count(value, "!")) / float64(utf8.RuneCountInString(value)) > 0.001 {
            return ""
        }
        return fmt.Sprintf("%s must contain more exclamation marks", field)
    })

    v.Register(Post{}) // Register all structs at load time

    p := Post{
        ID:       5,
        Title:    "Hi",
        Body:     "Hello world!",
        Category: "announcement",
    }

    vio, err := v.Violations(&p)
    if err != nil {
        log.Fatalln(err)
    }

    fmt.Println(vio)
}

Benchmarks

BenchmarkValidatorStringReqInvalid           192 ns/op        48 B/op          3 allocs/op
BenchmarkValidatorStringReqValid            98.5 ns/op        16 B/op          1 allocs/op
BenchmarkValidatorsVariety                  1114 ns/op       281 B/op         13 allocs/op

Contribute

Make a pull request.