validator

Under Reviewv0.1.0-alpha

The validator package provides common input validation helpers for request payloads. It wraps go-playground/validator/v10 for struct validation and provides standalone functions for email and password rules.

Import path: ecom-engine/pkg/validator

---

Functions

ValidateStruct

func ValidateStruct(s interface{}) error

Validates a struct's fields using go-playground/validator/v10 struct tags. Returns nil if all rules pass, or a validator.ValidationErrors describing each failed field.

type CreateProductRequest struct {
    Name  string  `validate:"required,min=1,max=200"`
    Price float64 `validate:"required,gt=0"`
    SKU   string  `validate:"required,alphanum"`
}

req := CreateProductRequest{Name: "", Price: -1}
if err := validator.ValidateStruct(req); err != nil {
    // err contains field-level validation errors
    response.GinWriteError(c, apperrors.NewBadRequest("invalid request", err))
    return
}

Common struct tag rules:

Tag	Description
required	Field must be non-zero
min=N	Minimum length (strings) or value (numbers)
max=N	Maximum length or value
email	Valid email format
gt=0	Greater than zero
alphanum	Alphanumeric characters only
oneof=a b c	Value must be one of the listed options
url	Valid URL

For the full list, see the go-playground/validator documentation.

---

ValidateEmail

func ValidateEmail(email string) error

Validates an email address using Go's standard net/mail.ParseAddress, then additionally checks that the domain part contains a . (dot). Returns errors.New("invalid email address") on failure.

Rules applied:

• Parseable by RFC 5322
• Contains @
• Domain portion contains .

if err := validator.ValidateEmail("user@example.com"); err != nil {
    return apperrors.NewBadRequest("invalid email", err)
}

---

ValidatePassword

func ValidatePassword(password string) error

Checks that the password meets minimum strength requirements.

Rule	Detail
Minimum length	At least 8 characters
Letter required	At least one Unicode letter
Digit required	At least one Unicode digit
Special character required	At least one character that is not a letter, digit, or whitespace

if err := validator.ValidatePassword(pw); err != nil {
    return apperrors.NewBadRequest(err.Error(), nil)
}

Error messages returned:

• "password must be at least 8 characters"
• "password must contain at least one letter, one number, and one special character"

---

Combining validators

For most handler request structs, use ValidateStruct first (covers field presence and format), then call ValidateEmail / ValidatePassword for the fields that need the stricter custom rules:

type RegisterRequest struct {
    Email    string `json:"email"    validate:"required"`
    Password string `json:"password" validate:"required"`
    Name     string `json:"name"     validate:"required,min=1,max=100"`
}

if err := validator.ValidateStruct(req); err != nil {
    response.GinWriteError(c, apperrors.NewBadRequest("invalid request body", err))
    return
}
if err := validator.ValidateEmail(req.Email); err != nil {
    response.GinWriteError(c, apperrors.NewBadRequest(err.Error(), nil))
    return
}
if err := validator.ValidatePassword(req.Password); err != nil {
    response.GinWriteError(c, apperrors.NewBadRequest(err.Error(), nil))
    return
}