Refactor form validation into a new type

I was worried that i was repeating the AddInputErrors function for each
form, because they were basically the same.  I could create a Form type
and make all forms embed it, but i realized that with a separate
validator i would have cleaner validation functions and would not need
the Valid field in the form that i am using only for that method.

pkg/form.go

@@ -2,6 +2,7 @@ package pkg
 
 import (
 	"context"
+	"errors"
 	"net/http"
 	"net/mail"
 	"strings"
@@ -25,19 +26,6 @@ func (field *InputField) FillValue(r *http.Request) {
 	field.Value = strings.TrimSpace(r.FormValue(field.Name))
 }
 
-func (field *InputField) Equals(other *InputField) bool {
-	return field.Value == other.Value
-}
-
-func (field *InputField) IsEmpty() bool {
-	return field.Value == ""
-}
-
-func (field *InputField) HasValidEmail() bool {
-	_, err := mail.ParseAddress(field.Value)
-	return err == nil
-}
-
 type SelectOption struct {
 	Value string
 	Label string
@@ -86,3 +74,48 @@ func MustGetOptions(ctx context.Context, conn *Conn, sql string, args ...interfa
 
 	return options
 }
+
+type FormValidator struct {
+	Valid bool
+}
+
+func newFormValidator() *FormValidator {
+	return &FormValidator{true}
+}
+
+func (v *FormValidator) AllOK() bool {
+	return v.Valid
+}
+
+func (v *FormValidator) CheckRequiredInput(field *InputField, message string) bool {
+	return v.checkInput(field, field.Value != "", message)
+}
+
+func (v *FormValidator) CheckValidEmailInput(field *InputField, message string) bool {
+	_, err := mail.ParseAddress(field.Value)
+	return v.checkInput(field, err == nil, message)
+}
+
+func (v *FormValidator) CheckPasswordConfirmation(password *InputField, confirm *InputField, message string) bool {
+	return v.checkInput(confirm, password.Value == confirm.Value, message)
+}
+
+func (v *FormValidator) CheckValidSelectOption(field *SelectField, message string) bool {
+	return v.checkSelect(field, field.HasValidOption(), message)
+}
+
+func (v *FormValidator) checkInput(field *InputField, ok bool, message string) bool {
+	if !ok {
+		field.Errors = append(field.Errors, errors.New(message))
+		v.Valid = false
+	}
+	return ok
+}
+
+func (v *FormValidator) checkSelect(field *SelectField, ok bool, message string) bool {
+	if !ok {
+		field.Errors = append(field.Errors, errors.New(message))
+		v.Valid = false
+	}
+	return ok
+}

pkg/login.go

@@ -23,7 +23,6 @@ type loginForm struct {
 	Errors   []error
 	Email    *InputField
 	Password *InputField
-	Valid    bool
 }
 
 func newLoginForm(locale *Locale) *loginForm {
@@ -63,21 +62,12 @@ func (form *loginForm) Parse(r *http.Request) error {
 }
 
 func (form *loginForm) Validate() bool {
-	form.Valid = true
+	validator := newFormValidator()
-	if form.Email.IsEmpty() {
+	if validator.CheckRequiredInput(form.Email, gettext("Email can not be empty.", form.locale)) {
-		form.AppendInputError(form.Email, errors.New(gettext("Email can not be empty.", form.locale)))
+		validator.CheckValidEmailInput(form.Email, gettext("This value is not a valid email. It should be like name@domain.com.", form.locale))
-	} else if !form.Email.HasValidEmail() {
-		form.AppendInputError(form.Email, errors.New(gettext("This value is not a valid email. It should be like name@domain.com.", form.locale)))
 	}
-	if form.Password.IsEmpty() {
+	validator.CheckRequiredInput(form.Password, gettext("Password can not be empty.", form.locale))
-		form.AppendInputError(form.Password, errors.New(gettext("Password can not be empty.", form.locale)))
+	return validator.AllOK()
-	}
-	return form.Valid
-}
-
-func (form *loginForm) AppendInputError(field *InputField, err error) {
-	field.Errors = append(field.Errors, err)
-	form.Valid = false
 }
 
 func LoginHandler() http.Handler {

pkg/profile.go

@@ -2,7 +2,6 @@ package pkg
 
 import (
 	"context"
-	"errors"
 	"net/http"
 )
 
@@ -18,7 +17,6 @@ type profileForm struct {
 	Password        *InputField
 	PasswordConfirm *InputField
 	Language        *SelectField
-	Valid           bool
 }
 
 func newProfileForm(ctx context.Context, conn *Conn, locale *Locale) *profileForm {
@@ -69,32 +67,14 @@ func (form *profileForm) Parse(r *http.Request) error {
 }
 
 func (form *profileForm) Validate() bool {
-	form.Valid = true
+	validator := newFormValidator()
-	if form.Email.IsEmpty() {
+	if validator.CheckRequiredInput(form.Email, gettext("Email can not be empty.", form.locale)) {
-		form.AppendInputError(form.Email, errors.New(gettext("Email can not be empty.", form.locale)))
+		validator.CheckValidEmailInput(form.Email, gettext("This value is not a valid email. It should be like name@domain.com.", form.locale))
-	} else if !form.Email.HasValidEmail() {
-		form.AppendInputError(form.Email, errors.New(gettext("This value is not a valid email. It should be like name@domain.com.", form.locale)))
 	}
-	if form.Name.IsEmpty() {
+	validator.CheckRequiredInput(form.Name, gettext("Name can not be empty.", form.locale))
-		form.AppendInputError(form.Name, errors.New(gettext("Name can not be empty.", form.locale)))
+	validator.CheckPasswordConfirmation(form.Password, form.PasswordConfirm, gettext("Confirmation does not match password.", form.locale))
-	}
+	validator.CheckValidSelectOption(form.Language, gettext("Selected language is not valid.", form.locale))
-	if !form.PasswordConfirm.Equals(form.Password) {
+	return validator.AllOK()
-		form.AppendInputError(form.PasswordConfirm, errors.New(gettext("Confirmation does not match password.", form.locale)))
-	}
-	if !form.Language.HasValidOption() {
-		form.AppendSelectError(form.Language, errors.New(gettext("Selected language is not valid.", form.locale)))
-	}
-	return form.Valid
-}
-
-func (form *profileForm) AppendInputError(field *InputField, err error) {
-	field.Errors = append(field.Errors, err)
-	form.Valid = false
-}
-
-func (form *profileForm) AppendSelectError(field *SelectField, err error) {
-	field.Errors = append(field.Errors, err)
-	form.Valid = false
 }
 
 func ProfileHandler() http.Handler {

po/ca.po

@@ -8,7 +8,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: numerus\n"
 "Report-Msgid-Bugs-To: jordi@tandem.blog\n"
-"POT-Creation-Date: 2023-02-01 10:52+0100\n"
+"POT-Creation-Date: 2023-02-01 11:26+0100\n"
 "PO-Revision-Date: 2023-01-18 17:08+0100\n"
 "Last-Translator: jordi fita mas <jordi@tandem.blog>\n"
 "Language-Team: Catalan <ca@dodds.net>\n"
@@ -142,7 +142,7 @@ msgid "Phone"
 msgstr "Telèfon"
 
 #: web/template/tax-details.gohtml:27 web/template/contacts-new.gohtml:27
-#: pkg/login.go:34 pkg/profile.go:37
+#: pkg/login.go:33 pkg/profile.go:35
 msgctxt "input"
 msgid "Email"
 msgstr "Correu-e"
@@ -221,56 +221,56 @@ msgctxt "title"
 msgid "New Contact"
 msgstr "Nou contacte"
 
-#: pkg/login.go:45 pkg/profile.go:43
+#: pkg/login.go:44 pkg/profile.go:41
 msgctxt "input"
 msgid "Password"
 msgstr "Contrasenya"
 
-#: pkg/login.go:68 pkg/profile.go:74
+#: pkg/login.go:66 pkg/profile.go:71
 msgid "Email can not be empty."
 msgstr "No podeu deixar el correu-e en blanc."
 
-#: pkg/login.go:70 pkg/profile.go:76
+#: pkg/login.go:67 pkg/profile.go:72
 msgid "This value is not a valid email. It should be like name@domain.com."
 msgstr "Aquest valor no és un correu-e vàlid. Hauria de ser similar a nom@domini.cat."
 
-#: pkg/login.go:73
+#: pkg/login.go:69
 msgid "Password can not be empty."
 msgstr "No podeu deixar la contrasenya en blanc."
 
-#: pkg/login.go:105
+#: pkg/login.go:95
 msgid "Invalid user or password."
 msgstr "Nom d’usuari o contrasenya incorrectes."
 
-#: pkg/profile.go:25
+#: pkg/profile.go:23
 msgctxt "language option"
 msgid "Automatic"
 msgstr "Automàtic"
 
-#: pkg/profile.go:31
+#: pkg/profile.go:29
 msgctxt "input"
 msgid "User name"
 msgstr "Nom d’usuari"
 
-#: pkg/profile.go:48
+#: pkg/profile.go:46
 msgctxt "input"
 msgid "Password Confirmation"
 msgstr "Confirmació contrasenya"
 
-#: pkg/profile.go:53
+#: pkg/profile.go:51
 msgctxt "input"
 msgid "Language"
 msgstr "Idioma"
 
-#: pkg/profile.go:79
+#: pkg/profile.go:74
 msgid "Name can not be empty."
 msgstr "No podeu deixar el nom en blanc."
 
-#: pkg/profile.go:82
+#: pkg/profile.go:75
 msgid "Confirmation does not match password."
 msgstr "La confirmació no és igual a la contrasenya."
 
-#: pkg/profile.go:85
+#: pkg/profile.go:76
 msgid "Selected language is not valid."
 msgstr "Heu seleccionat un idioma que no és vàlid."
 

po/es.po

@@ -7,7 +7,7 @@ msgid ""
 msgstr ""
 "Project-Id-Version: numerus\n"
 "Report-Msgid-Bugs-To: jordi@tandem.blog\n"
-"POT-Creation-Date: 2023-02-01 10:52+0100\n"
+"POT-Creation-Date: 2023-02-01 11:26+0100\n"
 "PO-Revision-Date: 2023-01-18 17:45+0100\n"
 "Last-Translator: jordi fita mas <jordi@tandem.blog>\n"
 "Language-Team: Spanish <es@tp.org.es>\n"
@@ -142,7 +142,7 @@ msgid "Phone"
 msgstr "Teléfono"
 
 #: web/template/tax-details.gohtml:27 web/template/contacts-new.gohtml:27
-#: pkg/login.go:34 pkg/profile.go:37
+#: pkg/login.go:33 pkg/profile.go:35
 msgctxt "input"
 msgid "Email"
 msgstr "Correo-e"
@@ -221,56 +221,56 @@ msgctxt "title"
 msgid "New Contact"
 msgstr "Nuevo contacto"
 
-#: pkg/login.go:45 pkg/profile.go:43
+#: pkg/login.go:44 pkg/profile.go:41
 msgctxt "input"
 msgid "Password"
 msgstr "Contraseña"
 
-#: pkg/login.go:68 pkg/profile.go:74
+#: pkg/login.go:66 pkg/profile.go:71
 msgid "Email can not be empty."
 msgstr "No podéis dejar el correo-e en blanco."
 
-#: pkg/login.go:70 pkg/profile.go:76
+#: pkg/login.go:67 pkg/profile.go:72
 msgid "This value is not a valid email. It should be like name@domain.com."
 msgstr "Este valor no es un correo-e válido. Tiene que ser parecido a nombre@dominio.es."
 
-#: pkg/login.go:73
+#: pkg/login.go:69
 msgid "Password can not be empty."
 msgstr "No podéis dejar la contaseña en blanco."
 
-#: pkg/login.go:105
+#: pkg/login.go:95
 msgid "Invalid user or password."
 msgstr "Nombre de usuario o contraseña inválido."
 
-#: pkg/profile.go:25
+#: pkg/profile.go:23
 msgctxt "language option"
 msgid "Automatic"
 msgstr "Automático"
 
-#: pkg/profile.go:31
+#: pkg/profile.go:29
 msgctxt "input"
 msgid "User name"
 msgstr "Nombre de usuario"
 
-#: pkg/profile.go:48
+#: pkg/profile.go:46
 msgctxt "input"
 msgid "Password Confirmation"
 msgstr "Confirmación contrasenya"
 
-#: pkg/profile.go:53
+#: pkg/profile.go:51
 msgctxt "input"
 msgid "Language"
 msgstr "Idioma"
 
-#: pkg/profile.go:79
+#: pkg/profile.go:74
 msgid "Name can not be empty."
 msgstr "No podéis dejar el nombre en blanco."
 
-#: pkg/profile.go:82
+#: pkg/profile.go:75
 msgid "Confirmation does not match password."
 msgstr "La confirmación no corresponde con la contraseña."
 
-#: pkg/profile.go:85
+#: pkg/profile.go:76
 msgid "Selected language is not valid."
 msgstr "Habéis escogido un idioma que no es válido."