Apparently, I want to return an array of struct based on the function parameter (getOccupationStructs function) in order to keep DRY (not using if else in every other functions), but it seems impossible to do, so here is my errors:
cannot use []Student literal (type []Student) as type []struct {} in
return argument
cannot use []Employee literal (type []Employee ) as type []struct {} in
return argument
and here is my code:
package main
import (
"fmt"
"time"
"github.com/jinzhu/gorm"
_ "github.com/jinzhu/gorm/dialects/postgres"
)
type Human struct {
ID uint `gorm:"primary_key" gorm:"column:_id" json:"_id"`
Name string `gorm:"column:name" json:"name"`
Age int `gorm:"column:age" json:"age"`
Phone string `gorm:"column:phone" json:"phone"`
}
type Student struct {
Human
School string `gorm:"column:school" json:"school"`
Loan float32 `gorm:"column:loan" json:"loan"`
}
type Employee struct {
Human
Company string `gorm:"column:company" json:"company"`
Money float32 `gorm:"column:money" json:"money"`
}
func getOccupationStructs(occupation string) []struct{} {
switch occupation {
case "student":
return []main.Student{}
case "employee":
return []main.Employee{}
default:
return []main.Student{}
}
}
func firstFunction(){
m := getOccupationStructs("student")
for _, value := range m{
fmt.Println("Hi, my name is "+value.Name+" and my school is "+value.School)
}
}
func secondFunction(){
m := getOccupationStructs("employee")
for _, value := range m{
fmt.Println("Hi, my name is "+value.Name+" and my company is "+value.Company)
}
}
Is there any valid workaround to cope this problem?
Go doesn't have structural subtyping, so to get polymorphism you'll need to use an interface.
Define an interface that all struct types implement, it can even be private, like interface embedsHuman { Name() string }, and then return []embedsHuman.
Alternatively, restructure your schema or only the Go representation of it as something less hierarchical (perhaps humans can have many roles?), so that it doesn't clash with Go's type system.