指南：如何保存和获取状态
使用键值对来持久化状态
介绍
状态管理是任何应用程序最常见的需求之一：无论是新是旧，是单体还是微服务。 与不同的数据库库打交道，进行测试，处理重试和故障是很费时费力的。
Dapr提供的状态管理功能包括一致性和并发选项。 在本指南中，我们将从基础知识开始。使用键/值状态API来允许应用程序保存，获取和删除状态。
前提
- Dapr CLI
- Initialized Dapr environment
第一步：设置状态存储
状态存储组件代表Dapr用来与数据库进行通信的资源。
For the purpose of this guide we’ll use a Redis state store, but any state store from the supported list will work.
当在单机模式下使用dapr init时，Dapr CLI会自动提供一个状态存储(Redis)，并在components目录中创建相关的YAML，在Linux/MacOS上位于$HOME/.dapr/components，在Windows上位于%USERPROFILE%/.dapr/components。
如果需要切换使用的状态存储引擎，用你选择的文件替换/components下的YAML文件statestore.yaml。
To deploy this into a Kubernetes cluster, fill in the metadata connection details of your desired statestore component in the yaml below, save as statestore.yaml, and run kubectl apply -f statestore.yaml.
apiVersion: dapr.io/v1alpha1
kind: Component
metadata:
name: statestore
namespace: default
spec:
type: state.redis
version: v1
metadata:
- name: redisHost
value: localhost:6379
- name: redisPassword
value: ""
See the instructions here on how to setup different state stores on Kubernetes.
第二步：保存和检索单个状态
下面的例子显示了如何使用Dapr状态构件的单个键/值对。
Note
设置一个app-id是很重要的，因为状态键是以这个值为前缀的。 如果你不设置，就会在运行期间为你自动生成一个值，而到下次运行命令时又会生成一个新的值，你将因此无法再访问以前保存的状态。首先启动一个Dapr sidecar：
dapr run --app-id myapp --dapr-http-port 3500
然后在一个单独的终端中保存一个键/值对到你的statestore中：
curl -X POST -H "Content-Type: application/json" -d '[{ "key": "key1", "value": "value1"}]' http://localhost:3500/v1.0/state/statestore
现在获取你刚才保存的状态：
curl http://localhost:3500/v1.0/state/statestore/key1
你也可以重启你的sidecar，然后再次尝试检索状态，看看存储的状态是否与应用状态保持一致。
首先启动Dapr sidecar:
dapr --app-id myapp --port 3500 run
然后在一个单独的终端中保存一个键/值对到你的statestore中:
Invoke-RestMethod -Method Post -ContentType 'application/json' -Body '[{"key": "key1", "value": "value1"}]' -Uri 'http://localhost:3500/v1.0/state/statestore'
现在获取你刚才保存的状态：
Invoke-RestMethod -Uri 'http://localhost:3500/v1.0/state/statestore/key1'
你也可以重启你的sidecar，然后再次尝试检索状态，看看存储的状态是否与应用状态保持一致。
将以下内容保存到名为pythonState.py的文件中:
from dapr.clients import DaprClient
with DaprClient() as d:
d.save_state(store_name="statestore", key="myFirstKey", value="myFirstValue" )
print("State has been stored")
data = d.get_state(store_name="statestore", key="myFirstKey").data
print(f"Got value: {data}")
保存后执行以下命令启动Dapr sidecar并运行Python应用程序:
dapr --app-id myapp run python pythonState.py
你应该会得到一个类似于下面的输出，它将同时显示Dapr和应用程序的日志:
== DAPR == time="2021-01-06T21:34:33.7970377-08:00" level=info msg="starting Dapr Runtime -- version 0.11.3 -- commit a1a8e11" app_id=Braidbald-Boot scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:34:33.8040378-08:00" level=info msg="standalone mode configured" app_id=Braidbald-Boot scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:34:33.8040378-08:00" level=info msg="app id: Braidbald-Boot" app_id=Braidbald-Boot scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:34:33.9750400-08:00" level=info msg="component loaded. name: statestore, type: state.redis" app_id=Braidbald-Boot scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:34:33.9760387-08:00" level=info msg="API gRPC server is running on port 51656" app_id=Braidbald-Boot scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:34:33.9770372-08:00" level=info msg="dapr initialized. Status: Running. Init Elapsed 172.9994ms" app_id=Braidbald-Boot scope=dapr.
Checking if Dapr sidecar is listening on GRPC port 51656
Dapr sidecar is up and running.
Updating metadata for app command: python pythonState.py
You are up and running! Both Dapr and your app logs will appear here.
== APP == State has been stored
== APP == Got value: b'myFirstValue' Status: Running. Init Elapsed 172.9994ms" app_id=Braidbald-Boot scope=dapr.
在state-example.php中保存以下内容:
<?php
require_once __DIR__.'/vendor/autoload.php';
$app = \Dapr\App::create();
$app->run(function(\Dapr\State\StateManager $stateManager, \Psr\Log\LoggerInterface $logger) {
$stateManager->save_state(store_name: 'statestore', item: new \Dapr\State\StateItem(
key: 'myFirstKey',
value: 'myFirstValue'
));
$logger->alert('State has been stored');
$data = $stateManager->load_state(store_name: 'statestore', key: 'myFirstKey')->value;
$logger->alert("Got value: {data}", ['data' => $data]);
});
保存后，执行以下命令启动Dapr sidecar并运行PHP应用程序:
dapr --app-id myapp run -- php state-example.php
你应该会得到一个类似于下面的输出，它将同时显示Dapr和应用程序的日志:
✅ You're up and running! Both Dapr and your app logs will appear here.
== APP == [2021-02-12T16:30:11.078777+01:00] APP.ALERT: State has been stored [] []
== APP == [2021-02-12T16:30:11.082620+01:00] APP.ALERT: Got value: myFirstValue {"data":"myFirstValue"} []
第三步：删除状态
下面的例子显示了如何通过给状态管理API传递一个键来删除一个对象:
用上面运行的同一个dapr实例执行:
curl -X DELETE 'http://localhost:3500/v1.0/state/statestore/key1'
再尝试获取状态，注意没有返回任何值。
用上面运行的同一个dapr实例执行:
Invoke-RestMethod -Method Delete -Uri 'http://localhost:3500/v1.0/state/statestore/key1'
再尝试获取状态，注意没有返回任何值。
修改pythonState.py如下：
from dapr.clients import DaprClient
with DaprClient() as d:
d.save_state(store_name="statestore", key="key1", value="value1" )
print("State has been stored")
data = d.get_state(store_name="statestore", key="key1").data
print(f"Got value: {data}")
d.delete_state(store_name="statestore", key="key1")
data = d.get_state(store_name="statestore", key="key1").data
print(f"Got value after delete: {data}")
现在通过以下命令运行你的程序:
dapr --app-id myapp run python pythonState.py
你应该会看到一个类似于下面的输出:
Starting Dapr with id Yakchocolate-Lord. HTTP Port: 59457. gRPC Port: 59458
== DAPR == time="2021-01-06T22:55:36.5570696-08:00" level=info msg="starting Dapr Runtime -- version 0.11.3 -- commit a1a8e11" app_id=Yakchocolate-Lord scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:55:36.5690367-08:00" level=info msg="standalone mode configured" app_id=Yakchocolate-Lord scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:55:36.7220140-08:00" level=info msg="component loaded. Status: Running. Init Elapsed 154.984ms" app_id=Yakchocolate-Lord scope=dapr.runtime type=log ver=0.11.3
Checking if Dapr sidecar is listening on GRPC port 59458
Dapr sidecar is up and running.
Updating metadata for app command: python pythonState.py
You're up and running!
== APP == State has been stored
== APP == Got value: b'value1'
== APP == Got value after delete: b''
修改state-example.php，内容如下:
<?php
require_once __DIR__.'/vendor/autoload.php';
$app = \Dapr\App::create();
$app->run(function(\Dapr\State\StateManager $stateManager, \Psr\Log\LoggerInterface $logger) {
$stateManager->save_state(store_name: 'statestore', item: new \Dapr\State\StateItem(
key: 'myFirstKey',
value: 'myFirstValue'
));
$logger->alert('State has been stored');
$data = $stateManager->load_state(store_name: 'statestore', key: 'myFirstKey')->value;
$logger->alert("Got value: {data}", ['data' => $data]);
$stateManager->delete_keys(store_name: 'statestore', keys: ['myFirstKey']);
$data = $stateManager->load_state(store_name: 'statestore', key: 'myFirstKey')->value;
$logger->alert("Got value after delete: {data}", ['data' => $data]);
});
现在使用以下命令运行它:
dapr --app-id myapp run -- php state-example.php
你应该会看到类似下面的输出:
✅ You're up and running!
== APP == [2021-02-12T16:38:00.839201+01:00] APP.ALERT: State has been stored [] []
== APP == [2021-02-12T16:38:00.841997+01:00] APP.ALERT: Got value: myFirstValue {"data":"myFirstValue"} []
== APP == [2021-02-12T16:38:00.845721+01:00] APP.ALERT: Got value after delete: {"data":null} []
第四步：保存和检索多个状态
Dapr还允许你在同一个调用中保存和检索多个状态:
在上面运行的同一个dapr实例中，将两个键/值对保存到你的statetore中:
curl -X POST -H "Content-Type: application/json" -d '[{ "key": "key1", "value": "value1"}, { "key": "key2", "value": "value2"}]' http://localhost:3500/v1.0/state/statestore
现在获取你刚才保存的状态：
curl -X POST -H "Content-Type: application/json" -d '{"keys":["key1", "key2"]}' http://localhost:3500/v1.0/state/statestore/bulk
在上面运行的同一个dapr实例中，将两个键/值对保存到你的statetore中:
Invoke-RestMethod -Method Post -ContentType 'application/json' -Body '[{ "key": "key1", "value": "value1"}, { "key": "key2", "value": "value2"}]' -Uri 'http://localhost:3500/v1.0/state/statestore'
现在获取你刚才保存的状态：
Invoke-RestMethod -Method Post -ContentType 'application/json' -Body '{"keys":["key1", "key2"]}' -Uri 'http://localhost:3500/v1.0/state/statestore/bulk'
StateItem对象可以使用save_states和get_states方法来存储多个Dapr状态。
用以下代码更新你的pythonState.py文件:
from dapr.clients import DaprClient
from dapr.clients.grpc._state import StateItem
with DaprClient() as d:
s1 = StateItem(key="key1", value="value1")
s2 = StateItem(key="key2", value="value2")
d.save_bulk_state(store_name="statestore", states=[s1,s2])
print("States have been stored")
items = d.get_bulk_state(store_name="statestore", keys=["key1", "key2"]).items
print(f"Got items: {[i.data for i in items]}")
现在通过以下命令运行你的程序:
dapr --app-id myapp run python pythonState.py
你应该会看到一个类似于下面的输出:
== DAPR == time="2021-01-06T21:54:56.7262358-08:00" level=info msg="starting Dapr Runtime -- version 0.11.3 -- commit a1a8e11" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:54:56.7401933-08:00" level=info msg="standalone mode configured" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:54:56.8754240-08:00" level=info msg="Initialized name resolution to standalone" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:54:56.8844248-08:00" level=info msg="component loaded. name: statestore, type: state.redis" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:54:56.8854273-08:00" level=info msg="API gRPC server is running on port 60614" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T21:54:56.8854273-08:00" level=info msg="dapr initialized. Status: Running. Init Elapsed 145.234ms" app_id=Musesequoia-Sprite scope=dapr.runtime type=log ver=0.11.3
Checking if Dapr sidecar is listening on GRPC port 60614
Dapr sidecar is up and running.
Updating metadata for app command: python pythonState.py
You're up and running!
== APP == States have been stored
== APP == Got items: [b'value1', b'value2']
要用PHP批量加载和保存状态，只需创建一个 “Plain Ole' PHP对象”(POPO)，并用 StateStore注解进行声明。
更新state-example.php文件:
<?php
require_once __DIR__.'/vendor/autoload.php';
#[\Dapr\State\Attributes\StateStore('statestore', \Dapr\consistency\EventualLastWrite::class)]
class MyState {
public string $key1 = 'value1';
public string $key2 = 'value2';
}
$app = \Dapr\App::create();
$app->run(function(\Dapr\State\StateManager $stateManager, \Psr\Log\LoggerInterface $logger) {
$obj = new MyState();
$stateManager->save_object(item: $obj);
$logger->alert('States have been stored');
$stateManager->load_object(into: $obj);
$logger->alert("Got value: {data}", ['data' => $obj]);
});
运行该应用:
dapr --app-id myapp run -- php state-example.php
并看到以下输出:
✅ You're up and running!
== APP == [2021-02-12T16:55:02.913801+01:00] APP.ALERT: States have been stored [] []
== APP == [2021-02-12T16:55:02.917850+01:00] APP.ALERT: Got value: [object MyState] {"data":{"MyState":{"key1":"value1","key2":"value2"}}} []
第五步：执行状态事务性操作
Note
状态事务性操作需要一个支持multi-item transactions的状态存储引擎。 Visit the supported state stores page page for a full list. 请注意，在自托管环境中创建的默认Redis容器是支持的。用上面运行的同一个dapr实例执行两个状态事务操作:
curl -X POST -H "Content-Type: application/json" -d '{"operations": [{"operation":"upsert", "request": {"key": "key1", "value": "newValue1"}}, {"operation":"delete", "request": {"key": "key2"}}]}' http://localhost:3500/v1.0/state/statestore/transaction
现在可以看到你的状态事务操作的结果:
curl -X POST -H "Content-Type: application/json" -d '{"keys":["key1", "key2"]}' http://localhost:3500/v1.0/state/statestore/bulk
在上面运行的同一个dapr实例中，将两个键/值对保存到你的statetore中:
Invoke-RestMethod -Method Post -ContentType 'application/json' -Body '{"operations": [{"operation":"upsert", "request": {"key": "key1", "value": "newValue1"}}, {"operation":"delete", "request": {"key": "key2"}}]}' -Uri 'http://localhost:3500/v1.0/state/statestore'
现在可以看到你的状态事务操作的结果:
Invoke-RestMethod -Method Post -ContentType 'application/json' -Body '{"keys":["key1", "key2"]}' -Uri 'http://localhost:3500/v1.0/state/statestore/bulk'
如果你的状态存储需要事务支持，可以考虑使用TransactionalStateOperation。
用以下代码更新你的pythonState.py文件:
from dapr.clients import DaprClient
from dapr.clients.grpc._state import StateItem
from dapr.clients.grpc._request import TransactionalStateOperation, TransactionOperationType
with DaprClient() as d:
s1 = StateItem(key="key1", value="value1")
s2 = StateItem(key="key2", value="value2")
d.save_bulk_state(store_name="statestore", states=[s1,s2])
print("States have been stored")
d.execute_state_transaction(
store_name="statestore",
operations=[
TransactionalStateOperation(key="key1", data="newValue1", operation_type=TransactionOperationType.upsert),
TransactionalStateOperation(key="key2", data="value2", operation_type=TransactionOperationType.delete)
]
)
print("State transactions have been completed")
items = d.get_bulk_state(store_name="statestore", keys=["key1", "key2"]).items
print(f"Got items: {[i.data for i in items]}")
现在通过以下命令运行你的程序:
dapr run python pythonState.py
你应该会看到一个类似于下面的输出:
Starting Dapr with id Singerchecker-Player. HTTP Port: 59533. gRPC Port: 59534
== DAPR == time="2021-01-06T22:18:14.1246721-08:00" level=info msg="starting Dapr Runtime -- version 0.11.3 -- commit a1a8e11" app_id=Singerchecker-Player scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:18:14.1346254-08:00" level=info msg="standalone mode configured" app_id=Singerchecker-Player scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:18:14.2747063-08:00" level=info msg="component loaded. name: statestore, type: state.redis" app_id=Singerchecker-Player scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:18:14.2757062-08:00" level=info msg="API gRPC server is running on port 59534" app_id=Singerchecker-Player scope=dapr.runtime type=log ver=0.11.3
== DAPR == time="2021-01-06T22:18:14.2767059-08:00" level=info msg="dapr initialized. Status: Running. Init Elapsed 142.0805ms" app_id=Singerchecker-Player scope=dapr.runtime type=log ver=0.11.3
Checking if Dapr sidecar is listening on GRPC port 59534
Dapr sidecar is up and running.
Updating metadata for app command: python pythonState.py
You're up and running!
== APP == State transactions have been completed
== APP == Got items: [b'value1', b'']
事务性状态通过扩展TransactionalState基础对象来支持，它挂接到你的 对象，然后通过setters和getters来提供事务。 而你可能会希望依赖注入框架来替你创建一个事务对象:
再次修改state-example.php文件:
<?php
require_once __DIR__.'/vendor/autoload.php';
#[\Dapr\State\Attributes\StateStore('statestore', \Dapr\consistency\EventualLastWrite::class)]
class MyState extends \Dapr\State\TransactionalState {
public string $key1 = 'value1';
public string $key2 = 'value2';
}
$app = \Dapr\App::create();
$app->run(function(MyState $obj, \Psr\Log\LoggerInterface $logger, \Dapr\State\StateManager $stateManager) {
$obj->begin();
$obj->key1 = 'hello world';
$obj->key2 = 'value3';
$obj->commit();
$logger->alert('Transaction committed!');
// begin a new transaction which reloads from the store
$obj->begin();
$logger->alert("Got value: {key1}, {key2}", ['key1' => $obj->key1, 'key2' => $obj->key2]);
});
运行程序:
dapr --app-id myapp run -- php state-example.php
观察到以下输出:
✅ You're up and running!
== APP == [2021-02-12T17:10:06.837110+01:00] APP.ALERT: Transaction committed! [] []
== APP == [2021-02-12T17:10:06.840857+01:00] APP.ALERT: Got value: hello world, value3 {"key1":"hello world","key2":"value3"} []
下一步
- Read the full State API reference
- Try one of the Dapr SDKs
- Build a stateful service
May 29, 2021: New Crowdin updates (#72) (602a67f8)