Golang : Is conversion between different struct types possible?

Question

Let's say I have two similar types set this way :

type type1 []struct {     Field1 string     Field2 int } type type2 []struct {     Field1 string     Field2 int } 

Is there a direct way to write values from a type1 to a type2, knowing that they have the same fields ? (other than writing a loop that will copy all the fields from the source to the target)

Thanks.

Answer 1

To give a reference to OneOfOne's answer, see the Conversions section of the spec.

It states that

A non-constant value x can be converted to type T in any of these cases:

• x is assignable to T.
• x's type and T have identical underlying types.
• x's type and T are unnamed pointer types and their pointer base types have identical underlying types.
• x's type and T are both integer or floating point types.
• x's type and T are both complex types.
• x is an integer or a slice of bytes or runes and T is a string type.
• x is a string and T is a slice of bytes or runes.

The first and highlighted case is your case. Both types have the underlying type

[]struct { Field1 string Field2 int } 

An underlying type is defined as

If T is one of the predeclared boolean, numeric, or string types, or a type literal, the corresponding underlying type is T itself. Otherwise, T's underlying type is the underlying type of the type to which T refers in its type declaration. (spec, Types)

You are using a type literal to define your type so this type literal is your underlying type.

Answer 2

For your specific example, you can easily convert it playground:

t1 := type1{{"A", 1}, {"B", 2}} t2 := type2(t1) fmt.Println(t2)