error type out of range when use for embed fields

[Mehrdad-Dadkhah]

hi
tnx for good package.

when I run this code:

       type Product struct {
		gorm.Model `view:"gorm"`
		Code string `view:"*"`
		Price uint `view:"*"`

	}


	product := &Product{}

	gormProduct := retag.Convert(product, retag.NewView("json", "gorm"))

	fmt.Println(gormProduct, reflect.TypeOf(gormProduct))

output error is:

runtime: typeOff 0xffffffffffffffed base 0xc4200ac700 not in ranges:
	types 0x66f000 etypes 0x72154c
fatal error: runtime: type offset base pointer out of range

goroutine 1 [running]:
runtime.throw(0x705437, 0x2e)
	/usr/local/go/src/runtime/panic.go:596 +0x95 fp=0xc42015d160 sp=0xc42015d140
runtime.resolveTypeOff(0xc4200ac700, 0xffffffed, 0x671d87)
	/usr/local/go/src/runtime/type.go:223 +0x350 fp=0xc42015d1c0 sp=0xc42015d160
runtime.(*_type).typeOff(0xc4200ac700, 0xffffffed, 0x671d87)
	/usr/local/go/src/runtime/type.go:239 +0x33 fp=0xc42015d1e8 sp=0xc42015d1c0
runtime.additab(0x7f2f9e916440, 0x101)
	/usr/local/go/src/runtime/iface.go:112 +0x1e2 fp=0xc42015d2d0 sp=0xc42015d1e8
runtime.getitab(0x6b6840, 0xc4200ac700, 0x4a1701, 0xc4200ac700)
	/usr/local/go/src/runtime/iface.go:79 +0x184 fp=0xc42015d368 sp=0xc42015d2d0
runtime.assertE2I2(0x6b6840, 0xc4200ac700, 0xc42014d880, 0x0, 0x0, 0x0)
	/usr/local/go/src/runtime/iface.go:294 +0x43 fp=0xc42015d398 sp=0xc42015d368
fmt.(*pp).handleMethods(0xc4200b63c0, 0xc400000076, 0x100)
	/usr/local/go/src/fmt/print.go:560 +0x70 fp=0xc42015d428 sp=0xc42015d398
fmt.(*pp).printValue(0xc4200b63c0, 0xc4200ac700, 0xc42012b6e8, 0x199, 0xc400000076, 0x3)
	/usr/local/go/src/fmt/print.go:695 +0x2d6b fp=0xc42015d620 sp=0xc42015d428
fmt.(*pp).printValue(0xc4200b63c0, 0xc42012b7a0, 0xc42012b6e0, 0x199, 0xc400000076, 0x2)
	/usr/local/go/src/fmt/print.go:778 +0x21de fp=0xc42015d818 sp=0xc42015d620
fmt.(*pp).printValue(0xc4200b63c0, 0xc42012b800, 0xc42012b6e0, 0x199, 0xc400000076, 0x1)
	/usr/local/go/src/fmt/print.go:778 +0x21de fp=0xc42015da10 sp=0xc42015d818
fmt.(*pp).printValue(0xc4200b63c0, 0xc42014f5c0, 0xc42012b6e0, 0x16, 0x76, 0x0)
	/usr/local/go/src/fmt/print.go:848 +0x1dd1 fp=0xc42015dc08 sp=0xc42015da10
fmt.(*pp).printArg(0xc4200b63c0, 0xc42014f5c0, 0xc42012b6e0, 0x76)
	/usr/local/go/src/fmt/print.go:682 +0x217 fp=0xc42015dc90 sp=0xc42015dc08
fmt.(*pp).doPrintln(0xc4200b63c0, 0xc42015de68, 0x1, 0x1)
	/usr/local/go/src/fmt/print.go:1138 +0xa1 fp=0xc42015dd08 sp=0xc42015dc90
fmt.Fprintln(0x826fc0, 0xc42008e008, 0xc42015de68, 0x1, 0x1, 0xc42012b6e0, 0x82df60, 0xc42012b800)
	/usr/local/go/src/fmt/print.go:247 +0x5c fp=0xc42015dd70 sp=0xc42015dd08
fmt.Println(0xc42015de68, 0x1, 0x1, 0xc42014d720, 0xc42014f5c0, 0xc42012b6e0)
	/usr/local/go/src/fmt/print.go:257 +0x57 fp=0xc42015ddc0 sp=0xc42015dd70
main.main()
	/home/shatranj/GoLang/gorpc/src/app/testRetag.go:62 +0x723 fp=0xc42015df88 sp=0xc42015ddc0
runtime.main()
	/usr/local/go/src/runtime/proc.go:185 +0x20a fp=0xc42015dfe0 sp=0xc42015df88
runtime.goexit()
	/usr/local/go/src/runtime/asm_amd64.s:2197 +0x1 fp=0xc42015dfe8 sp=0xc42015dfe0

goroutine 17 [syscall, locked to thread]:
runtime.goexit()
	/usr/local/go/src/runtime/asm_amd64.s:2197 +0x1
exit status 2

go version:

go version go1.8 linux/amd64

[sevlyar]

Thank you for the report! The issue should be fixed by 5656e2f commit, please check.

[Mehrdad-Dadkhah]

Thank you @sevlyar
yes it is fixed.
but unfortunately it was not useful for me! because retag change struct type to *struct.

for example in my sample code I need a struct with type Product but it return *struct and I can't cast it!

[sevlyar]

@Mehrdad-Dadkhah, You can use next code if you need a structure instead of pointer:

gormProductPtr := Convert(product, NewView("json", "gorm"))
gormProduct := reflect.ValueOf(gormProductPtr).Elem().Interface()

But i don't understand a source of your requirements. Could you clarify your case of retag using? It would help me to extend scope of using.

[Mehrdad-Dadkhah]

Thanks for reply @sevlyar

I test it but I have error!
My code is:

package main

import (
	"fmt"
	"github.com/sevlyar/retag"
	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
	"reflect"
)

func main() {
	type Product struct {
		gorm.Model `view:"gorm"`
		Code string `view:"*"`
		Price uint `view:"*"`

	}


	product := Product{}

	gormProductPtr := retag.Convert(product, retag.NewView("json", "gorm"))
	gormProduct := reflect.ValueOf(gormProductPtr).Elem().Interface()
	
	fmt.Println(gormProduct)
}

And error:

panic: reflect: Elem of invalid type

goroutine 1 [running]:
reflect.(*rtype).Elem(0x6bb980, 0xc42011f500, 0x99)
	/usr/local/go/src/reflect/type.go:954 +0xde
vendor/github.com/sevlyar/retag.Convert(0x6bb980, 0xc42011f500, 0x80dac0, 0xc42013f8e0, 0xc42014fea0, 0xc4200a4ce8)
	/home/shatranj/GoLang/gorpc/src/vendor/github.com/sevlyar/retag/tags.go:58 +0x7e
main.main()
	/home/shatranj/GoLang/gorpc/src/app/testRetag.go:22 +0x143
exit status 2

[Mehrdad-Dadkhah]

About my case, I have a adaptor for gorm orm and another one for other. Gorm need a struct that gorm.Model was embedded to it and another (for example X) orm don't need it.
I don't want to define two struct one for gorm and another for X orm so I need change struct definition and make a new struct in my adaptor base on in used orm.

[sevlyar]

@Mehrdad-Dadkhah Convert requires pointer (&product):

gormProductPtr := retag.Convert(&product, retag.NewView("json", "gorm"))

I will add semantic error message for that case.

[Mehrdad-Dadkhah]

@sevlyar
Yes it's work. I test it with this simple example:

package main

import (
	"fmt"
	"github.com/sevlyar/retag"
	"github.com/jinzhu/gorm"
	_ "github.com/jinzhu/gorm/dialects/mysql"
	"reflect"
)

func main() {
	type Product struct {
		gorm.Model `view:"gorm"`
		Code string `view:"*"`
		Price uint `view:"*"`

	}


	product := Product{}

	gormProductPtr := retag.Convert(&product, retag.NewView("json", "gorm"))
	gormProduct := reflect.ValueOf(gormProductPtr).Elem().Interface()
	fmt.Println("type of gormProduct : ",reflect.TypeOf(gormProduct))

	orginalProduct, _ := gormProduct.(Product);
	fmt.Println("type of orginalProduct : ", reflect.TypeOf(orginalProduct))

	connection, _ := gorm.Open("mysql", "root:2014@/gorpc?charset=utf8&parseTime=True&loc=Local")
	dbObj := connection.First(&orginalProduct, 1)

	fmt.Println("yes! gorm work with it fine. result: ")
	fmt.Println(orginalProduct, dbObj)
}

and output is:

type of gormProduct :  struct { Model gorm.Model; Code string; Price uint }
type of orginalProduct :  main.Product
yes! gorm work with it fine. result: 
{{1 2017-05-05 16:36:56 +0430 IRDT 2017-07-11 23:16:33 +0430 IRDT <nil>} L1212 2000} &{0xc42011f620 <nil> 1 <nil> 0xc42012d860 0xc42012d7c0 0xc4201257c0 0 {0xc4201380f0} <nil> false  map[gorm:order_by_primary_key:ASC] map[]}

one question:
Can we retrieve a type from a variable of that type?
I want to use it for casting ...
I want to cast a struct to another (for this case gormProduct with type of struct{} to orginalProduct with type of Product) when I have not straight access to Product type and just have a variable of that type.
is my question clear?

thanks very very much for help me @sevlyar

[sevlyar]

@Mehrdad-Dadkhah Convert just converts a type of the pointer. It doesn't allocate or copy memory:

    product := Product{}
    ptr := &product 
    newPtr := retag.Convert(ptr, retag.NewView("json", "gorm"))
    // Now ptr and newPtr both point on the same memory - product.

    // ...
    connection.First(&newPtr, 1)
    // Now fields of the product are completely filled by gorm:
    fmt.Println(product.Code, product.Price)

p.s.
I am sorry. I already written an answer on your question earlier but seems i have forgot to press 'Comment' button.