Go无法访问其他文件中的导出数据

Question

My project exports these values in different files:

//messages.go    
package types

    //BeaconMsg with data from google glass and the connected beacons
    type BeaconMsg struct {
        instanceID  int
        namespaceID int
        distance    int
    }

//beacondata.go
package types

import (
    "time"
)

//Beacondata with data from glasses containing beacon information
type Beacondata struct {
    instanceID   int
    namespaceID  int
    distance     int
    RegisterTime time.Time
}

In another file I import the types like this:

import (
    "glassbackend/types"
)

Code that throws the error:

req := new(types.BeaconMsg)
        if err := structFromRequest(req, r); err != nil {
            log.Errorf(context, "error extracting data from request %v", err)
            w.WriteHeader(http.StatusBadRequest)
            return
        }
        if req.namespaceID == "" || req.instanceID == "" {blab blabl}

but then this code throws me the error "req.namespaceID undefined (cannot refer to unexported field or method namespaceID)(build)

Note that the code req := new(types.BeaconMsg) does not cast any error, only the last row of my code.

Does anyone have any idea as to what is happening? Am I doing something wrong with the exports? I don't think there is much else to do either right or wrong?

Answer 1

You only exported the type BeaconMsg (the type name), but the fields are unexported.

If you want to access the fields too from other packages, you have to export them by starting their names with a capital letter:

type BeaconMsg struct {
    InstanceID  int
    NamespaceID int
    Distance    int
}