How to clear struct values except certain fields with struct's method

Question

I have a struct. I want to clear all fields except some public fields, e.g. Name, Gender, how to implement the function through method?

In my real code, I have many fields in the struct, so reset those sensitive fields manually is not my option.

type Agent struct {
    Name    string
    Gender  string
    Secret1 string
    Secret2 string
}

func (a *Agent) HideSecret() {
    fmt.Println("Hiding secret...")
    new := &Agent{
        Name:   a.Name,
        Gender: a.Gender,
    }
    a = new
}

I tried a few combination of * and &, but it seems not working... Please help.

    James := Agent{
        Name:    "James Bond",
        Gender:  "M",
        Secret1: "1234",
        Secret2: "abcd",
    }

    fmt.Printf("[Before] Secret: %s, %s\n", James.Secret1, James.Secret2)
    James.HideSecret()
    fmt.Printf("[After]  Secret: %s, %s\n", James.Secret1, James.Secret2) // not working

The golang playground is here: https://go.dev/play/p/ukJf2Fa0fPI

marc_s · Accepted Answer · 2025-11-06 20:33:53Z

2

The receiver is a pointer. You have to update the object that the pointer points to:

func (a *Agent) HideSecret() {
    fmt.Println("Hiding secret...")
    cleaned := Agent{
        Name:   a.Name,
        Gender: a.Gender,
    }
    *a=cleaned
}

edited Nov 6 at 20:33

marc_s

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answered Sep 28, 2022 at 18:56

Burak Serdar

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Comments

marc_s · Accepted Answer · 2025-11-06 20:33:45Z

0

If you want to just clear the fields, this is an easy solution; it saves some memory

func (a *Agent) HideSecret() {
   fmt.Println("Hiding secret...")
   a.Secret1 = ""
   a.Secret2 = ""
}

edited Nov 6 at 20:33

marc_s

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answered Sep 29, 2022 at 1:01

VithuBati

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