GoLang App Engine Struct Name

I was playing around with the AppEngine recently and came across an issue with the following code, where the only value that seemed to be written to the datastore was the Date. I spent a while banging my head on this to find that by simply capitalizing the first characters in the structs fixed it!

I was wondering if anyone else came across this and knows why I would be unable to use lowercase member names in the Golang struct for the datastore? I think that this may be a bug with the way the Google AppEngine handles struct writes.

Here's the problem code:

package main
import (
"fmt"
"net/http"
"time"
"appengine"
"appengine/datastore"
)
/* This is the problem struct */
type storeVal struct {
firstName    string  //FirstName works
lastName     string  //LastName works
email        string  //Email works
password     string  //Password works
Date         time.Time
}
func init() {
http.HandleFunc("/", handle)
http.ListenAndServe(":8080", nil)
}
func handle(w http.ResponseWriter, r *http.Request) {
c := appengine.NewContext(r)
/* Write values to DataStore */
e1 := storeVal{
firstName:     	"Bob",                 //FirstName works
lastName:     	"Smith",               //lastName works
email: 		    "bob.smith@test.com",  //Email works
password:  	    "password!",           //Password works
Date:  		    time.Now(),
}
key := datastore.NewIncompleteKey(c, "storeVal", nil)
_, err := datastore.Put(c, key, &e1)
if err != nil {
http.Error(w, err.Error(), http.StatusInternalServerError)
return
}
fmt.Fprintf(w, "successfully added {firstName: '%s', lastName: '%s', email: '%s', password: '%s'}", e1.firstName, e1.lastName, e1.email, e1.password)
/* Read values back in. */
q := datastore.NewQuery("storeVal").
Filter("firstName =", "Bob").
Filter("lastName =", "Smith").
Order("-Date")
var storeVals []storeVal
_, err2 := q.GetAll(c, &storeVals)
if err2 != nil {
http.Error(w, err2.Error(), http.StatusInternalServerError)
return
}
if (len(storeVals) == 0) {
fmt.Printf("No results.");
return
}
e2 := storeVals[0]
fmt.Fprintf(w, "successfully grabbed {firstName: '%s', lastName: '%s', email: '%s', password: '%s', uaprem: '%s'}", e2.firstName, e2.lastName, e2.email, e2.password)
}

It's related to how Go handles the "public" and "private" concept.

To export you do need the field names in caps. This can help explain that... it is related to JSON but it applies here as both cases require exporting the data from a struct.

This is from the Eager blog post on Go and JSON, which I found helpful:

> The Field Name
>
> As you might know, Go requires all exported fields to start with a
> capitalized letter.
> It’s not common to use that style in JSON however.
> We use the tag to let the parser know where to actually look for the
> value.
>
>
>
> You can see an example of that in the example above, but as a
> refresher this is what it looks like:
>
> type MyStruct struct {
> SomeField string json:"some_field"
> }