golang / mgo：从插入中删除空字段

For some reason mgo inserts the empty struct into the db as null value even though I've set omitempty option.

package main

import (
    "fmt"
    "encoding/json"
)

type A struct {
    A bool
}

type B struct {
    X       int `json:"x,omitempty" bson:"x,omitempty"`
    SomeA   *A `json:"a,omitempty" bson:"a,omitempty"`
}

func main() {
    b := B{}
    b.X = 123

    if buf, err := json.MarshalIndent(&b, "", " "); err != nil {
        fmt.Println(err)
    } else {
        fmt.Println(string(buf))
    }
}

The json encoder leaves out the SomeA property but in the database it's there as "a" : null. Am I doing something wrong, or it's simply not possible to do it this way?

Yeah, so problem was having tabs between the json and bson encoder options, that's why omitempty didn't work. So this is wrong:

SomeA   *A `json:"a,omitempty"         bson:"a,omitempty"`

Instead just have a single space and it's all good:

SomeA   *A `json:"a,omitempty" bson:"a,omitempty"`