dholtzmann/formvalidator

Simple form validation for Golang

formvalidator

Go package for validating just web forms (url.Values), not structs, maps, or unknown types.

You can write custom error messages and create a custom validation rule by implementing the "Rule" interface.

	type Rule interface {
		Validate([]string, map[string]string) (error, []interface{})
	}

It also includes a couple of functions for rendering radio buttons, checkboxes, and single or multiple selects/dropdowns.

Installation

go get -u github.com/dholtzmann/formvalidator

Basic Example

	package main

	import (
		"html/template"
		"net/http"

		fv "github.com/dholtzmann/formvalidator"
	)

	func main() {
		// setup HTTP server...
	}

	func indexPage(w http.ResponseWriter, r *http.Request) {
		tpl := template.Must(template.ParseGlob("./templates/*.html"))

		err := r.ParseForm()
		if err != nil {
			panic(err.Error())
		}
		/*
			For file uploads and a form.

			err := r.ParseMultipartForm(1 << 20)
			if err != nil {
				panic(err.Error())
			}
		*/

		rules := map[string][]fv.Rule{
			"Email": fv.RuleChain(fv.Required(), fv.Email(true), fv.StrLen(6, 50)),
			"Age":   fv.RuleChain(fv.Numeric(), fv.IntRange(18, 100)),
			// More validation rules...
		}

		err, validator := fv.New(rules)
		if err != nil {
			panic(err.Error())
		}

		isValid, errors := validator.Validate(r.Form) // or r.PostForm, r.MultipartForm.Value
		if isValid {
			// save to database, parse, ...
		} else {
			// display errors
			tplVars := make(map[string]interface{})
			tplVars["FormErrors"] = errors
			err = tpl.ExecuteTemplate(w, "index.gohtml", tplVars)
		}
	}

Validation rules

rules-string.go

• Required()
• RequiredMultiple()
• Email(allowThrowawayDomains bool)
• AlphaNumeric()
• MinStrLen(min uint32)
• MaxStrLen(max uint32)
• StrLen(min, max uint32)
• UTF8LetterNum()
• StrMatch(form.Get("ConfirmPassword"))
• IsJSON()
• WebRequestURI()
• Boolean()

rules-numeric.go

• Numeric()
• IntRange(min, max int)
• IsFloat64()
• FloatRange(min, max float64)
• CreditCard(allowTestingNumbers bool)
• Latitude()
• Longitude()
• ISBN() [format: Strlen 10 or 13]
• IsUUID(version uint32) [format: UUIDv3, UUIDv4, UUIDv5]
• IsDate() [format: DD-MM-YYYY]
• IsTime() [format: HH:MM:SS]
• IsDateTime() [format: DD-MM-YYYY HH:MM:SS]

rules-list.go

• CSVEntryStrLen(delimiter rune, minLenValue, maxLenValue uint32)
• CountryCode() [format: ISO-3166, 2 letters]
• InListMultiple(list []string)
• InListSingle(list []string)
• NotInListSingle(list []string)
• CurrencyCode() [format: ISO-4217, 3 letters]
• NotCommonPassword()

See the file 'validator_test.go' for examples of how to use the validation rules.

Todo

• Write Go documentation in comments. (typical godoc.org format)
• Expand README.md