How to use reflect.Type.Implements

see: https://stackoverflow.com/questions/18570391/check-if-struct-implements-a-given-interface

ou've unfortunately left out the essential parts (please always post complete programs), so I can only guess that the problem is in a method defined on a pointer receiver, in which case the behavior of your code is expected. Check this example and its output:

package main
import (
        "fmt"
        "reflect"
)
type Model interface {
        m()
}
func HasModels(m Model) {
        s := reflect.ValueOf(m).Elem()
        t := s.Type()
        modelType := reflect.TypeOf((*Model)(nil)).Elem()
        for i := 0; i < s.NumField(); i++ {
                f := t.Field(i)
                fmt.Printf("%d: %s %s -> %t\n", i, f.Name, f.Type, f.Type.Implements(modelType))
        }
}
type Company struct{}
func (Company) m() {}
type Department struct{}
func (*Department) m() {}
type User struct {
        CompanyA    Company
        CompanyB    *Company
        DepartmentA Department
        DepartmentB *Department
}