Utils (pointer & conversion helpers)

gitlab.finema.co/finema/idin-core/v2/utils — small, dependency-free generics for the pointer/enum juggling that request→model mapping needs.

Pointer basics

p := utils.ToPointer("hello")          // string  → *string
v := utils.ToNonPointer(p)             // *string → string (zero value if nil)
v := utils.ToNonPointerOr(p, "def")    // *string → string, "def" if nil

Converting enum pointers

A request DTO usually carries *string, while the model wants *SomeEnum (a type SomeEnum string). Instead of the verbose deref → convert → re-pointer:

// before — long and easy to get wrong
var projectType *models.PMOProjectType
if input.Type != nil {
    projectType = utils.ToPointer(models.PMOProjectType(utils.ToNonPointer(input.Type)))
}

// after — one nil-safe call
projectType := utils.PtrConvert[models.PMOProjectType](input.Type)

Inline in a struct literal it stays short:

pmoProject := &models.PMOProject{
    BaseModel:   models.NewBaseModel(),
    Name:        input.Name,
    Status:      models.PMOProjectStatusIntro,
    Type:        utils.PtrConvert[models.PMOProjectType](input.Type), // *string → *PMOProjectType
    Code:        input.Code,
    CreatedByID: utils.ToPointer(s.ctx.GetUser().ID),
}

It works both ways (e.g. building an output DTO):

resp.Type = utils.PtrConvert[string](pmoProject.Type) // *PMOProjectType → *string

R is given explicitly; the source type is inferred; nil in → nil out.

Numeric enums

For type Priority int and friends use PtrConvertNum:

priority := utils.PtrConvertNum[models.Priority](input.Priority) // *int → *models.Priority

Anything else — MapPtr

For non-trivial conversions (structs, formatting), pass a function; still nil-safe:

createdAt := utils.MapPtr(model.CreatedAt, func(t time.Time) string {
    return t.Format(time.RFC3339)
})

API

func ToPointer[T any](v T) *T
func ToNonPointer[T any](p *T) T
func ToNonPointerOr[T any](p *T, def T) T
func PtrConvert[R ~string, T ~string](p *T) *R    // string enums
func PtrConvertNum[R Numeric, T Numeric](p *T) *R // numeric enums
func MapPtr[T, R any](p *T, fn func(T) R) *R       // custom conversions

Slices

utils.DerefSlice([]*string{p1, nil, p3})      // []*T → []T (zero for nil)
utils.PtrSlice([]int{1, 2})                   // []T  → []*T
utils.Map([]int{1, 2}, func(n int) int { return n*2 })   // → [2 4]
utils.Filter(xs, func(x T) bool { return ... })
utils.Contains([]string{"a", "b"}, "b")       // true
utils.Unique([]int{1, 2, 2, 3})               // [1 2 3]

JSON & structs

utils.JSONToString(v)          // compact JSON string ("" on error)
utils.StructToString(v)        // pretty (indented) JSON string
utils.MapToStruct(src, &dst)   // struct/map → struct via JSON
utils.MapTo[User](src)         // generic: returns (User, error)
utils.StructToMap(v)           // → map[string]any
utils.JSONParse(body, &dst)    // unmarshal with a friendly type-error message
utils.Copy(&dst, src)          // deep copy matching fields (jinzhu/copier)
utils.IsEmpty(x)               // nil or zero value (any)
utils.IsZero(v)                // zero value (comparable, generic)

UUID / time

utils.NewUUID()        // random UUID string
utils.IsUUID(s)        // validate (fixed vs v1)
utils.ParseUUID(s)     // (uuid.UUID, error)
utils.NowPtr()         // *time.Time = now

Crypto / encoding

utils.SHA256(s) / SHA384(s) / SHA512(s)   // hex digests
utils.MD5(s)                              // checksums/etags only (not security)
utils.Base64Encode(s) / Base64Decode(s)
utils.HexEncode(b) / HexDecode(s)
utils.HashPassword(pw)                    // bcrypt → (string, error)
utils.ComparePassword(hash, pw)           // bool

Changes from v1

v1	v2
GetString/GetInt/GetBool/…	ToNonPointer[T] (generic) + ToNonPointerOr
GetArrayString	DerefSlice[T] (generic)
GetUUID	NewUUID
GetCurrentDateTime	NowPtr
NewSha256/384/512	SHA256/384/512
GetMD5Hash	MD5
HashPassword returns *string	returns string
IsUUID (broken FromBytes)	fixed (uuid.Parse)
DID / ECDSA-RSA keypairs / sign-verify / GetBigNumber (0x/0b) / MockExplorer	removed — domain-specific, belongs in the consuming service
utils.IsStrIn / IsExists (govalidator+gorm)	removed — use the valid package