Cannot Embed Non-Interface Type in Interface

Why This Happens

Go interfaces can only embed other interfaces, not concrete types. If you need to combine behaviors from a struct and an interface, use a struct with both an embedded struct and an embedded interface.

The Problem

type MyStruct struct {
    Name string
}

type MyInterface interface {
    MyStruct // cannot embed non-interface type
    DoWork()
}

The Fix

type Namer interface {
    GetName() string
}

type MyInterface interface {
    Namer
    DoWork()
}

Step-by-Step Fix

1. 1

   Identify the wrong embedding

   Find the interface definition that tries to embed a struct type.

2. 2

   Extract an interface

   Define an interface with the methods you need from the struct.

3. 3

   Embed the interface

   Embed the new interface into the original interface definition.