How to Omit Empty Nested Structs in Go JSON Marshal?

Go JSON Marshal: Omitting Empty Nested Structs

The json:",omitempty" tag in Go allows you to exclude fields that have empty values from JSON output. However, this behavior does not apply to zero-value structs.

To omit a nested struct if it has any empty fields, you can use a pointer instead of a non-pointer struct. This ensures that the struct is treated as empty if it has not been assigned a non-zero value.

For example, consider the following struct:

type ColorGroup struct {
    ID     int `json:",omitempty"`
    Name   string
    Colors []string
}

type Total struct {
    A *ColorGroup `json:",omitempty"` // Use pointer
    B string       `json:",omitempty"`
}

In this case, if group.A is not assigned a non-zero value, it will be treated as empty and omitted from JSON output. This is in contrast to using a non-pointer struct, which would still include the empty group.A in JSON output.

The following playground link demonstrates this behavior: https://play.golang.org/p/3i7rh4e3t3D

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