将十六进制值存储为字节导致丢失

I tried to store a hexdecimal value like

url.Values{"key": {"Value"}, "id": {"123"}})
"

in a []byte value on Google Appengine Datastore.

foo := Bar{
    HexdecimalContent:    []byte(content)
}

If I try to read this, all hexdecimal values like &34; will result in a "(MISSING)" (other characters are shown correct!). Now I save the data encoded in base64.

But why, is it needed to encode it in base64?

You should consider using encoding/json package for serializing map types into the datastore

values := map[string]string{"key1": "value1", "key2": "value2"}
bytes, err := json.Marshal(values)
if err != nil {
    return err
}   
foo := &Bar{Content: bytes}