验证是否在struct golang中设置了该字段

Question

I have the following struct:

type Foo struct {
    Bar *FooBar
    Baz *FooBaz
}

type FooBar struct {
    Name string
}

type FooBaz struct {
    Name string
}

How can I access the Baz and Bar in the struct without getting a nil pointer reference when they're not set?

I want something that goes like the below, but I keep getting nil pointer dereference errors.

if Foo.Bar == nil {
  throw error
}

I'm struggling with this!

Answer 1

You should be able to compare to nil, here's a working example:

check := func(f Foo) {
  if f.Bar == nil {
    panic("oops!")
  }
  fmt.Println("OK")
}

foo1 := Foo{Bar: &FooBar{"Alpha"}}
check(foo1) // OK

foo2 := Foo{}
check(foo2) // panic: oops!

Note that if you were to modify the "check" function to accept a *Foo and it was called with a nil pointer then that function would itself panic with a "nil pointer dereference runtime error". This might be what is currently happening with your example.