Golang cloud-google-com-go-datastore.NewKey类(方法)实例源码

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_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 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 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 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 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 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 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.
}