mirror of
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568 lines
13 KiB
Go
568 lines
13 KiB
Go
// Copyright 2014 Google Inc. All Rights Reserved.
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//
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// Licensed under the Apache License, Version 2.0 (the "License");
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// you may not use this file except in compliance with the License.
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// You may obtain a copy of the License at
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//
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// http://www.apache.org/licenses/LICENSE-2.0
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//
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// Unless required by applicable law or agreed to in writing, software
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// distributed under the License is distributed on an "AS IS" BASIS,
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// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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// See the License for the specific language governing permissions and
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// limitations under the License.
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package datastore_test
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import (
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"fmt"
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"log"
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"time"
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"cloud.google.com/go/datastore"
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"golang.org/x/net/context"
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"google.golang.org/api/iterator"
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)
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func ExampleNewClient() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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_ = client // TODO: Use client.
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}
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func ExampleClient_Get() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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type Article struct {
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Title string
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Description string
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Body string `datastore:",noindex"`
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Author *datastore.Key
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PublishedAt time.Time
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}
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key := datastore.NameKey("Article", "articled1", nil)
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article := &Article{}
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if err := client.Get(ctx, key, article); err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_Put() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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type Article struct {
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Title string
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Description string
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Body string `datastore:",noindex"`
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Author *datastore.Key
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PublishedAt time.Time
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}
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newKey := datastore.IncompleteKey("Article", nil)
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_, err = client.Put(ctx, newKey, &Article{
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Title: "The title of the article",
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Description: "The description of the article...",
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Body: "...",
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Author: datastore.NameKey("Author", "jbd", nil),
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PublishedAt: time.Now(),
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})
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if err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_Put_flatten() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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log.Fatal(err)
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}
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type Animal struct {
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Name string
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Type string
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Breed string
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}
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type Human struct {
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Name string
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Height int
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Pet Animal `datastore:",flatten"`
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}
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newKey := datastore.IncompleteKey("Human", nil)
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_, err = client.Put(ctx, newKey, &Human{
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Name: "Susan",
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Height: 67,
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Pet: Animal{
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Name: "Fluffy",
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Type: "Cat",
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Breed: "Sphynx",
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},
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})
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if err != nil {
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log.Fatal(err)
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}
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}
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func ExampleClient_Delete() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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key := datastore.NameKey("Article", "articled1", nil)
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if err := client.Delete(ctx, key); err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_DeleteMulti() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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var keys []*datastore.Key
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for i := 1; i <= 10; i++ {
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keys = append(keys, datastore.IDKey("Article", int64(i), nil))
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}
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if err := client.DeleteMulti(ctx, keys); err != nil {
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// TODO: Handle error.
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}
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}
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type Post struct {
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Title string
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PublishedAt time.Time
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Comments int
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}
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func ExampleClient_GetMulti() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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keys := []*datastore.Key{
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datastore.NameKey("Post", "post1", nil),
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datastore.NameKey("Post", "post2", nil),
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datastore.NameKey("Post", "post3", nil),
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}
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posts := make([]Post, 3)
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if err := client.GetMulti(ctx, keys, posts); err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_PutMulti_slice() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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keys := []*datastore.Key{
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datastore.NameKey("Post", "post1", nil),
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datastore.NameKey("Post", "post2", nil),
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}
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// PutMulti with a Post slice.
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posts := []*Post{
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{Title: "Post 1", PublishedAt: time.Now()},
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{Title: "Post 2", PublishedAt: time.Now()},
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}
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if _, err := client.PutMulti(ctx, keys, posts); err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_PutMulti_interfaceSlice() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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keys := []*datastore.Key{
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datastore.NameKey("Post", "post1", nil),
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datastore.NameKey("Post", "post2", nil),
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}
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// PutMulti with an empty interface slice.
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posts := []interface{}{
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&Post{Title: "Post 1", PublishedAt: time.Now()},
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&Post{Title: "Post 2", PublishedAt: time.Now()},
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}
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if _, err := client.PutMulti(ctx, keys, posts); err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleNewQuery() {
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// Query for Post entities.
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q := datastore.NewQuery("Post")
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_ = q // TODO: Use the query with Client.Run.
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}
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func ExampleNewQuery_options() {
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// Query to order the posts by the number of comments they have recieved.
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q := datastore.NewQuery("Post").Order("-Comments")
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// Start listing from an offset and limit the results.
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q = q.Offset(20).Limit(10)
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_ = q // TODO: Use the query.
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}
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func ExampleClient_Count() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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// Count the number of the post entities.
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q := datastore.NewQuery("Post")
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n, err := client.Count(ctx, q)
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if err != nil {
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// TODO: Handle error.
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}
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fmt.Printf("There are %d posts.", n)
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}
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func ExampleClient_Run() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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// List the posts published since yesterday.
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yesterday := time.Now().Add(-24 * time.Hour)
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q := datastore.NewQuery("Post").Filter("PublishedAt >", yesterday)
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it := client.Run(ctx, q)
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_ = it // TODO: iterate using Next.
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}
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func ExampleClient_NewTransaction() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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const retries = 3
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// Increment a counter.
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// See https://cloud.google.com/appengine/articles/sharding_counters for
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// a more scalable solution.
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type Counter struct {
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Count int
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}
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key := datastore.NameKey("counter", "CounterA", nil)
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var tx *datastore.Transaction
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for i := 0; i < retries; i++ {
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tx, err = client.NewTransaction(ctx)
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if err != nil {
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break
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}
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var c Counter
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if err = tx.Get(key, &c); err != nil && err != datastore.ErrNoSuchEntity {
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break
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}
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c.Count++
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if _, err = tx.Put(key, &c); err != nil {
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break
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}
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// Attempt to commit the transaction. If there's a conflict, try again.
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if _, err = tx.Commit(); err != datastore.ErrConcurrentTransaction {
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break
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}
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}
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if err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleClient_RunInTransaction() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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// Increment a counter.
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// See https://cloud.google.com/appengine/articles/sharding_counters for
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// a more scalable solution.
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type Counter struct {
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Count int
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}
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var count int
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key := datastore.NameKey("Counter", "singleton", nil)
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_, err = client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
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var x Counter
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if err := tx.Get(key, &x); err != nil && err != datastore.ErrNoSuchEntity {
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return err
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}
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x.Count++
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if _, err := tx.Put(key, &x); err != nil {
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return err
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}
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count = x.Count
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return nil
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})
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if err != nil {
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// TODO: Handle error.
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}
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// The value of count is only valid once the transaction is successful
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// (RunInTransaction has returned nil).
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fmt.Printf("Count=%d\n", count)
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}
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func ExampleClient_AllocateIDs() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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var keys []*datastore.Key
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for i := 0; i < 10; i++ {
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keys = append(keys, datastore.IncompleteKey("Article", nil))
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}
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keys, err = client.AllocateIDs(ctx, keys)
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if err != nil {
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// TODO: Handle error.
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}
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_ = keys // TODO: Use keys.
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}
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func ExampleKey_Encode() {
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key := datastore.IDKey("Article", 1, nil)
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encoded := key.Encode()
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fmt.Println(encoded)
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// Output: EgsKB0FydGljbGUQAQ
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}
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func ExampleDecodeKey() {
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const encoded = "EgsKB0FydGljbGUQAQ"
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key, err := datastore.DecodeKey(encoded)
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if err != nil {
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// TODO: Handle error.
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}
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fmt.Println(key)
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// Output: /Article,1
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}
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func ExampleIDKey() {
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// Key with numeric ID.
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k := datastore.IDKey("Article", 1, nil)
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_ = k // TODO: Use key.
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}
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func ExampleNameKey() {
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// Key with string ID.
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k := datastore.NameKey("Article", "article8", nil)
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_ = k // TODO: Use key.
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}
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func ExampleIncompleteKey() {
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k := datastore.IncompleteKey("Article", nil)
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_ = k // TODO: Use incomplete key.
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}
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func ExampleClient_GetAll() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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var posts []*Post
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keys, err := client.GetAll(ctx, datastore.NewQuery("Post"), &posts)
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for i, key := range keys {
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fmt.Println(key)
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fmt.Println(posts[i])
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}
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}
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func ExampleClient_Mutate() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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key1 := datastore.NameKey("Post", "post1", nil)
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key2 := datastore.NameKey("Post", "post2", nil)
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key3 := datastore.NameKey("Post", "post3", nil)
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key4 := datastore.NameKey("Post", "post4", nil)
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_, err = client.Mutate(ctx,
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datastore.NewInsert(key1, Post{Title: "Post 1"}),
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datastore.NewUpsert(key2, Post{Title: "Post 2"}),
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datastore.NewUpdate(key3, Post{Title: "Post 3"}),
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datastore.NewDelete(key4))
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if err != nil {
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// TODO: Handle error.
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}
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}
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func ExampleCommit_Key() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "")
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if err != nil {
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// TODO: Handle error.
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}
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var pk1, pk2 *datastore.PendingKey
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// Create two posts in a single transaction.
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commit, err := client.RunInTransaction(ctx, func(tx *datastore.Transaction) error {
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var err error
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pk1, err = tx.Put(datastore.IncompleteKey("Post", nil), &Post{Title: "Post 1", PublishedAt: time.Now()})
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if err != nil {
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return err
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}
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pk2, err = tx.Put(datastore.IncompleteKey("Post", nil), &Post{Title: "Post 2", PublishedAt: time.Now()})
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if err != nil {
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return err
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}
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return nil
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})
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if err != nil {
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// TODO: Handle error.
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}
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// Now pk1, pk2 are valid PendingKeys. Let's convert them into real keys
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// using the Commit object.
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k1 := commit.Key(pk1)
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k2 := commit.Key(pk2)
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fmt.Println(k1, k2)
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}
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func ExampleIterator_Next() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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it := client.Run(ctx, datastore.NewQuery("Post"))
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for {
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var p Post
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key, err := it.Next(&p)
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if err == iterator.Done {
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break
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}
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if err != nil {
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// TODO: Handle error.
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}
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fmt.Println(key, p)
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}
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}
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func ExampleIterator_Cursor() {
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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it := client.Run(ctx, datastore.NewQuery("Post"))
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for {
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var p Post
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_, err := it.Next(&p)
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if err == iterator.Done {
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break
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}
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if err != nil {
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// TODO: Handle error.
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}
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fmt.Println(p)
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cursor, err := it.Cursor()
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if err != nil {
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// TODO: Handle error.
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}
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// When printed, a cursor will display as a string that can be passed
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// to datastore.NewCursor.
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fmt.Printf("to resume with this post, use cursor %s\n", cursor)
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}
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}
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func ExampleDecodeCursor() {
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// See Query.Start for a fuller example of DecodeCursor.
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// getCursor represents a function that returns a cursor from a previous
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// iteration in string form.
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cursorString := getCursor()
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cursor, err := datastore.DecodeCursor(cursorString)
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if err != nil {
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// TODO: Handle error.
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}
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_ = cursor // TODO: Use the cursor with Query.Start or Query.End.
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}
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func getCursor() string { return "" }
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func ExampleQuery_Start() {
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// This example demonstrates how to use cursors and Query.Start
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// to resume an iteration.
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ctx := context.Background()
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client, err := datastore.NewClient(ctx, "project-id")
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if err != nil {
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// TODO: Handle error.
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}
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// getCursor represents a function that returns a cursor from a previous
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// iteration in string form.
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cursorString := getCursor()
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cursor, err := datastore.DecodeCursor(cursorString)
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if err != nil {
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// TODO: Handle error.
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}
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it := client.Run(ctx, datastore.NewQuery("Post").Start(cursor))
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_ = it // TODO: Use iterator.
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}
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func ExampleLoadStruct() {
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type Player struct {
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User string
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Score int
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}
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// Normally LoadStruct would only be used inside a custom implementation of
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// PropertyLoadSaver; this is for illustrative purposes only.
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props := []datastore.Property{
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{Name: "User", Value: "Alice"},
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{Name: "Score", Value: int64(97)},
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}
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var p Player
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if err := datastore.LoadStruct(&p, props); err != nil {
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// TODO: Handle error.
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}
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fmt.Println(p)
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// Output: {Alice 97}
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}
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func ExampleSaveStruct() {
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type Player struct {
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User string
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Score int
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}
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p := &Player{
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User: "Alice",
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Score: 97,
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}
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props, err := datastore.SaveStruct(p)
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if err != nil {
|
|
// TODO: Handle error.
|
|
}
|
|
fmt.Println(props)
|
|
// TODO(jba): make this output stable: Output: [{User Alice false} {Score 97 false}]
|
|
}
|