How to use value objects¶

Objective¶

Expose a richer model type while preserving the sqlc-generated persistence type.

Define the value object¶

package content

type Email struct {
    value string
}

func ParseEmail(value string) (Email, error) {
    // Normalize and validate.
}

func (e Email) String() string {
    return e.value
}

Configure conversion¶

fields:
  email:
    value_object:
      type: Email
      constructor: ParseEmail
      accessor: String

Generated hydration¶

email, err := ParseEmail(row.Email)
if err != nil {
    return nil, fmt.Errorf("User.Email: %w", err)
}

Generated persistence conversion¶

arg := user.Email().String()

Avoid implicit wrapper assumptions¶

The generator must not treat every type mismatch as a pgtype wrapper with .Valid and a value field. Conversion is valid only when types are directly assignable, covered by a known supported mapping, or explicitly configured.

Keep value-object behavior handwritten¶

The generator emits conversion calls and field plumbing. Validation rules and domain behavior remain in developer-owned source files.