initial commit

internal/validation/validation.go

@@ -0,0 +1,75 @@
+package validation
+
+import (
+	"errors"
+	"fmt"
+
+	"github.com/go-playground/validator/v10"
+)
+
+var customMessages = map[string]string{
+	"required":         "Field %s is required",
+	"required_strict":  "Field %s is required and cannot be null or empty",
+	"omitempty_strict": "Field %s cannot be null or empty when provided",
+
+	"email":    "Invalid email address for field %s",
+	"min":      "Field %s must have a minimum length of %s characters",
+	"max":      "Field %s must have a maximum length of %s characters",
+	"len":      "Field %s must be exactly %s characters long",
+	"number":   "Field %s must be a number",
+	"positive": "Field %s must be a positive number",
+	"alphanum": "Field %s must contain only alphanumeric characters",
+	"oneof":    "Invalid value for field %s",
+	"password": "Field %s must be at least 8 characters, contain uppercase, lowercase, number, and special character",
+}
+
+func CustomErrorMessages(err error) map[string]string {
+	var validationErrors validator.ValidationErrors
+	if errors.As(err, &validationErrors) {
+		return generateErrorMessages(validationErrors)
+	}
+	return nil
+}
+
+func generateErrorMessages(validationErrors validator.ValidationErrors) map[string]string {
+	errorsMap := make(map[string]string)
+	for _, err := range validationErrors {
+		fieldName := err.StructNamespace()
+		tag := err.Tag()
+
+		customMessage := customMessages[tag]
+		if customMessage != "" {
+			errorsMap[fieldName] = formatErrorMessage(customMessage, err, tag)
+		} else {
+			errorsMap[fieldName] = defaultErrorMessage(err)
+		}
+	}
+	return errorsMap
+}
+
+func formatErrorMessage(customMessage string, err validator.FieldError, tag string) string {
+	if tag == "min" || tag == "max" || tag == "len" {
+		return fmt.Sprintf(customMessage, err.Field(), err.Param())
+	}
+	return fmt.Sprintf(customMessage, err.Field())
+}
+
+func defaultErrorMessage(err validator.FieldError) string {
+	return fmt.Sprintf("Field validation for '%s' failed on the '%s' tag", err.Field(), err.Tag())
+}
+
+func Validator() *validator.Validate {
+	validate := validator.New()
+
+	if err := validate.RegisterValidation("password", Password); err != nil {
+		return nil
+	}
+	if err := validate.RegisterValidation("required_strict", RequiredStrict); err != nil {
+		return nil
+	}
+	if err := validate.RegisterValidation("omitempty_strict", OmitemptyStrict); err != nil {
+		return nil
+	}
+
+	return validate
+}