Google App Engine - Difference between local Dev server and deployed server - google-app-engine

Question

I'm writing an app on the Google App Engine, and I have been able to write code that runs locally and puts data into the local datastore. However, when I deploy the code to the google server, no data is put into the datastore. My primary indicators that nothing is getting put into the datastore are, one, when I go to the Developer Console, I'm told there are no entries, and two, when I run the page that gets data, nothing is returned.
Do I need to define new Kinds in the app.yaml or developer console before they will work on the production datastore?
Here is my put and get methods from the data store. Again, works in the testing environment and does not work in production, everything compiles just fine.
package tweetdata
import (
"net/url"
"time"
"golang.org/x/net/context"
"google.golang.org/appengine/datastore"
"google.golang.org/appengine/log"
"github.com/ChimeraCoder/anaconda"
)
const linkTweetKind string = "LinkTweet"
const tweetKey string = "Tweets"
const tweetKeyID string = "default_tweetstore"
//LinkTweet contains the address extracted from a tweet and the original tweet
type LinkTweet struct {
Address *url.URL
Tweet anaconda.Tweet
}
//StoreTweet is a struct used for storing a tweet in the datastore
type StoreTweet struct {
Address string
Text string
TweetID int64
CreatedTime time.Time
Retweets int
Favorites int
}
//TweetScore is a struct that shows the relative score of an address based on
// it's populatrity
type TweetScore struct {
Address *url.URL
score int
lastActive time.Time
}
//WriteLinkTweet writes a given Tweet to the datastore
func WriteLinkTweet(tweet LinkTweet, c context.Context) error {
log.Infof(c, "Putting Tweet into datastore: %v", tweet.Tweet.Id)
key := datastore.NewIncompleteKey(c, linkTweetKind, getTweetKey(c))
created, _ := tweet.Tweet.CreatedAtTime()
store := &StoreTweet{Address: tweet.Address.String(),
Text: tweet.Tweet.Text,
TweetID: tweet.Tweet.Id,
CreatedTime: created,
Retweets: tweet.Tweet.RetweetCount,
Favorites: tweet.Tweet.FavoriteCount,
}
err := datastore.RunInTransaction(c, func(c context.Context) error {
_, err := datastore.Put(c, key, store)
log.Errorf(c, "Failed to write LinkTweet to datastore. %v", err.Error())
return err
}, nil)
return err
}
//GetAllNewTweets queries the datastore and gets all tweets created since the last
// time given
func GetAllNewTweets(since time.Time, c context.Context) []StoreTweet {
q := datastore.NewQuery(linkTweetKind).Ancestor(getTweetKey(c)).Filter("CreatedTime >=", since)
out := make([]StoreTweet, 0, 15)
q.GetAll(c, &out)
return out
}
// guestbookKey returns the key used for all guestbook entries.
func getTweetKey(c context.Context) *datastore.Key {
// The string "default_guestbook" here could be varied to have multiple guestbooks.
return datastore.NewKey(c, tweetKey, tweetKeyID, 0, nil)
}

Answer 1

You're seeing the (often initially confusing) effect of "eventual consistency". Entities that are written outside of a transaction take a while to be visible to queries.
https://cloud.google.com/datastore/docs/articles/balancing-strong-and-eventual-consistency-with-google-cloud-datastore/ explains the problem. https://cloud.google.com/appengine/docs/go/datastore/transactions is specific to go.

Answer 2

Are you using datastore:,noindex on any fields in the StoreTweet struct? In order to run any query against any fields, the datastore must first index the fields you'll be querying. So not indexing those fields will cause the query to return nil without any errors. Does your dev server automatically create an index.yaml file in your project after running your queries for the first time? The production datastore uses this file to decide which fields should be indexed, all fields not indexed won't be able to be queried. From the information you've provided, this is all I can think of that would be causing your queries to return empty.
In order to debug this further, I would browse your production datastore and make sure your data is structured properly and the values are set to what you are expecting them to be.