How to override the way a structure field is converted to JSON?

In Go, to override the way a struct field is converted to JSON, you can implement the json.Marshaler interface for the entire struct or for a specific field if it is a type with a MarshalJSON() method. This allows you to define custom serialization logic.

Example for a field with a custom type:

package main

import (
    "encoding/json"
    "fmt"
)

type CustomType int

func (c CustomType) MarshalJSON() ([]byte, error) {
    // Convert the number to a string with a prefix
    return json.Marshal(fmt.Sprintf("custom-%d", c))
}

type MyStruct struct {
    Field CustomType `json:"field"`
}

func main() {
    s := MyStruct{Field: 42}
    data, _ := json.Marshal(s)
    fmt.Println(string(data)) // Output: {"field":"custom-42"}
}

If you want to change the serialization of the entire struct, implement the MarshalJSON() method for the struct as a whole.