JSONB for postgres in Golang

JSONB.go

// Found in this issue thread https://github.com/jinzhu/gorm/issues/516#issuecomment-109055198
// License unknown
//
//
// Postgres' JSONB type. It's a byte array of already encoded JSON (like json.RawMessage)
// which also saves itself correctly to PG's jsonb type.  It would probably also work on
// PG json types.
type JSONB []byte

func (j JSONB) Value() (driver.Value, error) {
    if j.IsNull() {
        //      log.Trace("returning null")
        return nil, nil
    }
    return string(j), nil
}

func (j *JSONB) Scan(value interface{}) error {
    if value == nil {
        *j = nil
        return nil
    }
    s, ok := value.([]byte)
    if !ok {
        errors.New("Scan source was not string")
    }
    // I think I need to make a copy of the bytes.
    // It seems the byte slice passed in is re-used
    *j = append((*j)[0:0], s...)

    return nil
}

// MarshalJSON returns *m as the JSON encoding of m.
func (m JSONB) MarshalJSON() ([]byte, error) {
    if m == nil {
        return []byte("null"), nil
    }
    return m, nil
}

// UnmarshalJSON sets *m to a copy of data.
func (m *JSONB) UnmarshalJSON(data []byte) error {
    if m == nil {
        return errors.New("json.RawMessage: UnmarshalJSON on nil pointer")
    }
    *m = append((*m)[0:0], data...)
    return nil
}

func (j JSONB) IsNull() bool {
    return len(j) == 0 || string(j) == "null"
}

func (j JSONB) Equals(j1 JSONB) bool {
    return bytes.Equal([]byte(j), []byte(j1))
}