嵌入匿名结构

Question

I'm trying to figure out how to embed an anonymous struct within another struct, for json parsing purposes.

I have an "extras" map that contains different attributes dependent on various factors. This map is a field of a larger json blob. I'd like to fully model out the various possibilities of the "extras" map so I can avoid using type assertions. I would like to have the "extras" structs be separate from the base struct (the rest of the json). I know I can do something like this:

type TestObj1 struct {
    ExtraObj `json:"extras"`
}

type ExtraObj struct {
    Foo string `json:"foo"`
}

This works great, because the json parses exactly how I would expect, and I can directly access Foo like so testObj1.Foo. The problem with this method is that now I have 2 different structs per possible "extras" variation, instead of 1. So then I could try something like this:

type TestObj2 struct {
    Extras struct {
        Foo string `json:"foo"`
    } `json:"extras"`
}

This also parses the json as expected, and gets rid of the need for 2 structs per variation. But the problem is, to access Foo, I need to go through Extras like so testObj2.Extras.Foo. I was hoping for a best of both worlds solution like so:

type TestObj3 struct {
    struct {
        Foo string `json:"foo"`
    } `json:"extras"`
}

But this is a compile error. A quick playground link I put together for this.

Is there any way to accomplish something like this, or is it not possible in the language? Your help is greatly appreciated!

Answer 1

Try the following:

type TestObj1 struct {
    ExO ExtraObj `json:"extras"`
}

type ExtraObj struct {
    Foo string `json:"foo"`
}

I did not test it myself, but should work.