func ExampleNewKey_withParent() {
ctx := context.Background()
// [START key_with_parent]
parentKey := datastore.NewKey(ctx, "TaskList", "default", 0, nil)
taskKey := datastore.NewKey(ctx, "Task", "sampleTask", 0, parentKey)
// [END key_with_parent]
_ = taskKey // Use the task key for datastore operations.
}
func ExampleNewKey() {
ctx := context.Background()
// Key with numeric ID.
k1 := datastore.NewKey(ctx, "Article", "", 1, nil)
// Key with string ID.
k2 := datastore.NewKey(ctx, "Article", "article8", 0, nil)
_, _ = k1, k2 // TODO: Use keys.
}
func ExampleNewKey_withMultipleParents() {
ctx := context.Background()
// [START key_with_multilevel_parent]
userKey := datastore.NewKey(ctx, "User", "alice", 0, nil)
parentKey := datastore.NewKey(ctx, "TaskList", "default", 0, userKey)
taskKey := datastore.NewKey(ctx, "Task", "sampleTask", 0, parentKey)
// [END key_with_multilevel_parent]
_ = taskKey // Use the task key for datastore operations.
}
func ExampleWithNamespace() {
ctx := context.Background()
// k1 is in the default namespace.
k1 := datastore.NewKey(ctx, "Article", "", 1, nil)
// k2 is in the "other" namespace.
ctx2 := datastore.WithNamespace(ctx, "other")
k2 := datastore.NewKey(ctx2, "Article", "", 1, nil)
// k1 and k2 can refer to different entities, despite the same kind and ID.
fmt.Printf("k1: %q\n", k1.Namespace())
fmt.Printf("k2: %q\n", k2.Namespace())
// Output:
// k1: ""
// k2: "other"
}
func pollCommits(dir string) {
cmd := execGit(dir, "pull_origin", nil, "pull", "origin")
out, err := cmd.CombinedOutput()
if err != nil {
log.Printf("Error running git pull origin master in %s: %v\n%s", dir, err, out)
return
}
log.Printf("Ran git pull.")
// TODO: see if .git/refs/remotes/origin/master
// changed. (quicker than running recentCommits each time)
hashes, err := recentCommits(dir)
if err != nil {
log.Print(err)
return
}
latestHash.Lock()
latestHash.s = hashes[0]
latestHash.Unlock()
for _, commit := range hashes {
if knownCommit[commit] {
continue
}
if dsClient != nil {
ctx := context.Background()
key := datastore.NewKey(ctx, "git_commit", commit, 0, nil)
var gc GitCommit
if err := dsClient.Get(ctx, key, &gc); err == nil && gc.Emailed {
log.Printf("Already emailed about commit %v; skipping", commit)
knownCommit[commit] = true
continue
}
}
if err := emailCommit(dir, commit); err == nil {
log.Printf("Emailed commit %s", commit)
knownCommit[commit] = true
if dsClient != nil {
ctx := context.Background()
key := datastore.NewKey(ctx, "git_commit", commit, 0, nil)
_, err := dsClient.Put(ctx, key, &GitCommit{Emailed: true})
log.Printf("datastore put of git_commit(%v): %v", commit, err)
}
}
}
if githubSSHKey != "" {
if err := syncToGithub(dir, hashes[0]); err != nil {
log.Printf("Failed to push commit %v to github: %v", hashes[0], err)
}
}
}
// Set writes the key, value pair to cs. But it does not actually write if the
// value already exists, is up to date, and is more recent than 30 days.
func (cs cachedStore) Set(key, value string) error {
// check if record already exists
ctx := context.Background()
dk := datastore.NewKey(ctx, "camnetdns", key, 0, nil)
var oldValue dsValue
if err := cs.dsClient.Get(ctx, dk, &oldValue); err != nil {
if err != datastore.ErrNoSuchEntity {
return fmt.Errorf("error checking if record exists for %q from datastore: %v", key, err)
}
// record does not exist, write it.
return cs.put(ctx, key, value)
}
// record already exists
if oldValue.Record != value {
// new record is different, overwrite old one.
return cs.put(ctx, key, value)
}
// record is the same as before
if oldValue.Updated.Add(staleRecord).After(time.Now()) {
// record is still fresh, nothing to do.
return nil
}
// record is older than 30 days, so we rewrite it, for analytics.
return cs.put(ctx, key, value)
}
func ExampleClient_Put() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
type Article struct {
Title string
Description string
Body string `datastore:",noindex"`
Author *datastore.Key
PublishedAt time.Time
}
newKey := datastore.NewIncompleteKey(ctx, "Article", nil)
_, err = client.Put(ctx, newKey, &Article{
Title: "The title of the article",
Description: "The description of the article...",
Body: "...",
Author: datastore.NewKey(ctx, "Author", "jbd", 0, nil),
PublishedAt: time.Now(),
})
if err != nil {
// TODO: Handle error.
}
}
func ExampleClient_RunInTransaction() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
// Increment a counter.
// See https://cloud.google.com/appengine/articles/sharding_counters for
// a more scalable solution.
type Counter struct {
Count int
}
var count int
key := datastore.NewKey(ctx, "Counter", "singleton", 0, nil)
_, err = client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
var x Counter
if err := tx.Get(key, &x); err != nil && err != datastore.ErrNoSuchEntity {
return err
}
x.Count++
if _, err := tx.Put(key, &x); err != nil {
return err
}
count = x.Count
return nil
})
if err != nil {
// TODO: Handle error.
}
// The value of count is only valid once the transaction is successful
// (RunInTransaction has returned nil).
fmt.Printf("Count=%d\n", count)
}
func ExampleKey_Encode() {
ctx := context.Background()
key := datastore.NewKey(ctx, "Article", "", 1, nil)
encoded := key.Encode()
fmt.Println(encoded)
// Output: EgsKB0FydGljbGUQAQ
}
func ExampleNewKey() {
ctx := context.Background()
// [START named_key]
taskKey := datastore.NewKey(ctx, "Task", "sampletask", 0, nil)
// [END named_key]
_ = taskKey // Use the task key for datastore operations.
}
func ExampleGetMulti() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
log.Fatal(err)
}
keys := []*datastore.Key{
datastore.NewKey(ctx, "Post", "post1", 0, nil),
datastore.NewKey(ctx, "Post", "post2", 0, nil),
datastore.NewKey(ctx, "Post", "post3", 0, nil),
}
posts := make([]Post, 3)
if err := client.GetMulti(ctx, keys, posts); err != nil {
log.Println(err)
}
}
func ExampleClient_GetMulti() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
keys := []*datastore.Key{
datastore.NewKey(ctx, "Post", "post1", 0, nil),
datastore.NewKey(ctx, "Post", "post2", 0, nil),
datastore.NewKey(ctx, "Post", "post3", 0, nil),
}
posts := make([]Post, 3)
if err := client.GetMulti(ctx, keys, posts); err != nil {
// TODO: Handle error.
}
}
func ExampleQuery_EventualConsistency() {
ctx := context.Background()
// [START eventual_consistent_query]
ancestor := datastore.NewKey(ctx, "TaskList", "default", 0, nil)
query := datastore.NewQuery("Task").Ancestor(ancestor).EventualConsistency()
// [END eventual_consistent_query]
_ = query // Use client.Run or client.GetAll to execute the query.
}
func ExampleQuery_keyFilter() {
ctx := context.Background()
// [START key_filter]
key := datastore.NewKey(ctx, "Task", "someTask", 0, nil)
query := datastore.NewQuery("Task").Filter("__key__ >", key)
// [END key_filter]
_ = query // Use client.Run or client.GetAll to execute the query.
}
func ExampleClient_Delete() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
key := datastore.NewKey(ctx, "Task", "sampletask", 0, nil)
// [START delete]
err := client.Delete(ctx, key)
// [END delete]
_ = err // Make sure you check err.
}
func ExampleClient_Get() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
taskKey := datastore.NewKey(ctx, "Task", "sampleTask", 0, nil)
// [START lookup]
var task Task
err := client.Get(ctx, taskKey, &task)
// [END lookup]
_ = err // Make sure you check err.
}
func ExampleClient_PutMulti_interfaceSlice() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
keys := []*datastore.Key{
datastore.NewKey(ctx, "Post", "post1", 0, nil),
datastore.NewKey(ctx, "Post", "post2", 0, nil),
}
// PutMulti with an empty interface slice.
posts := []interface{}{
&Post{Title: "Post 1", PublishedAt: time.Now()},
&Post{Title: "Post 2", PublishedAt: time.Now()},
}
if _, err := client.PutMulti(ctx, keys, posts); err != nil {
// TODO: Handle error.
}
}
func ExampleClient_Delete() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
key := datastore.NewKey(ctx, "Article", "articled1", 0, nil)
if err := client.Delete(ctx, key); err != nil {
// TODO: Handle error.
}
}
func ExamplePutMulti_slice() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
log.Fatal(err)
}
keys := []*datastore.Key{
datastore.NewKey(ctx, "Post", "post1", 0, nil),
datastore.NewKey(ctx, "Post", "post2", 0, nil),
}
// PutMulti with a Post slice.
posts := []*Post{
{Title: "Post 1", PublishedAt: time.Now()},
{Title: "Post 2", PublishedAt: time.Now()},
}
if _, err := client.PutMulti(ctx, keys, posts); err != nil {
log.Fatal(err)
}
}
func ExampleDelete() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
log.Fatal(err)
}
key := datastore.NewKey(ctx, "Article", "articled1", 0, nil)
if err := client.Delete(ctx, key); err != nil {
log.Fatal(err)
}
}
func (cs cachedStore) put(ctx context.Context, key, value string) error {
dk := datastore.NewKey(ctx, "camnetdns", key, 0, nil)
val := &dsValue{
Record: value,
Updated: time.Now(),
}
if _, err := cs.dsClient.Put(ctx, dk, val); err != nil {
return fmt.Errorf("error writing (%q : %q) record to datastore: %v", key, value, err)
}
// and cache it.
cs.cache.Add(key, value)
return nil
}
func ExampleClient_DeleteMulti() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
var keys []*datastore.Key
for i := 1; i <= 10; i++ {
keys = append(keys, datastore.NewKey(ctx, "Article", "", int64(i), nil))
}
if err := client.DeleteMulti(ctx, keys); err != nil {
// TODO: Handle error.
}
}
func ExampleTransaction_runQuery() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
// [START transactional_single_entity_group_read_only]
tx, err := client.NewTransaction(ctx)
if err != nil {
log.Fatalf("client.NewTransaction: %v", err)
}
defer tx.Rollback() // Transaction only used for read.
ancestor := datastore.NewKey(ctx, "TaskList", "default", 0, nil)
query := datastore.NewQuery("Task").Ancestor(ancestor).Transaction(tx)
var tasks []Task
_, err = client.GetAll(ctx, query, &tasks)
// [END transactional_single_entity_group_read_only]
_ = err // Check error.
}
func Example_metadataPropertiesForKind() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
// [START property_by_kind_run_query]
kindKey := datastore.NewKey(ctx, "__kind__", "Task", 0, nil)
query := datastore.NewQuery("__property__").Ancestor(kindKey)
type Prop struct {
Repr []string `datastore:"property_representation"`
}
var props []Prop
keys, err := client.GetAll(ctx, query, &props)
// [END property_by_kind_run_query]
_ = err // Check error.
_ = keys // Use keys to find property names, and props for their representations.
}
func ExampleTransaction_insert() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
task := Task{} // Populated with appropriate data.
taskKey := datastore.NewKey(ctx, "Task", "sampleTask", 0, nil)
// [START insert]
_, err := client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
// We first check that there is no entity stored with the given key.
var empty Task
if err := tx.Get(taskKey, &empty); err != datastore.ErrNoSuchEntity {
return err
}
// If there was no matching entity, store it now.
_, err := tx.Put(taskKey, &task)
return err
})
// [END insert]
_ = err // Make sure you check err.
}
func (cs cachedStore) Get(key string) (string, error) {
val, ok := cs.cache.Get(key)
if ok {
return val.(string), nil
}
// Cache Miss. hit the datastore.
ctx := context.Background()
dk := datastore.NewKey(ctx, "camnetdns", key, 0, nil)
var value dsValue
if err := cs.dsClient.Get(ctx, dk, &value); err != nil {
if err != datastore.ErrNoSuchEntity {
return "", fmt.Errorf("error getting value for %q from datastore: %v", key, err)
}
return "", errRecordNotFound
}
// And cache it.
cs.cache.Add(key, value.Record)
return value.Record, nil
}
func ExampleClient_Put() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
// [START entity_with_parent]
parentKey := datastore.NewKey(ctx, "TaskList", "default", 0, nil)
key := datastore.NewIncompleteKey(ctx, "Task", parentKey)
task := Task{
Category: "Personal",
Done: false,
Priority: 4,
Description: "Learn Cloud Datastore",
}
// A complete key is assigned to the entity when it is Put.
var err error
key, err = client.Put(ctx, key, &task)
// [END entity_with_parent]
_ = err // Make sure you check err.
}
func ExampleClient_Get() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
type Article struct {
Title string
Description string
Body string `datastore:",noindex"`
Author *datastore.Key
PublishedAt time.Time
}
key := datastore.NewKey(ctx, "Article", "articled1", 0, nil)
article := &Article{}
if err := client.Get(ctx, key, article); err != nil {
// TODO: Handle error.
}
}
func ExampleClient_NewTransaction() {
ctx := context.Background()
client, err := datastore.NewClient(ctx, "project-id")
if err != nil {
// TODO: Handle error.
}
const retries = 3
// Increment a counter.
// See https://cloud.google.com/appengine/articles/sharding_counters for
// a more scalable solution.
type Counter struct {
Count int
}
key := datastore.NewKey(ctx, "counter", "CounterA", 0, nil)
var tx *datastore.Transaction
for i := 0; i < retries; i++ {
tx, err = client.NewTransaction(ctx)
if err != nil {
break
}
var c Counter
if err = tx.Get(key, &c); err != nil && err != datastore.ErrNoSuchEntity {
break
}
c.Count++
if _, err = tx.Put(key, &c); err != nil {
break
}
// Attempt to commit the transaction. If there's a conflict, try again.
if _, err = tx.Commit(); err != datastore.ErrConcurrentTransaction {
break
}
}
if err != nil {
// TODO: Handle error.
}
}
func ExampleTransaction_getOrCreate() {
ctx := context.Background()
client, _ := datastore.NewClient(ctx, "my-proj")
key := datastore.NewKey(ctx, "Task", "sampletask", 0, nil)
// [START transactional_get_or_create]
_, err := client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
var task Task
if err := tx.Get(key, &task); err != datastore.ErrNoSuchEntity {
return err
}
_, err := tx.Put(key, &Task{
Category: "Personal",
Done: false,
Priority: 4,
Description: "Learn Cloud Datastore",
})
return err
})
// [END transactional_get_or_create]
_ = err // Check error.
}