快速入门 redis-cli
使用 redis-cli 的触发器和函数入门
| Redis 堆栈 | Redis 社区版 | Redis 企业软件 | Redis 云 | Redis 社区版 | 适用于 Kubernetes 的 Redis Enterprise | 客户 |
|---|
确保您已安装并运行 Redis Stack。或者，您可以创建一个免费的 Redis Cloud 帐户。触发器和函数预览版在 Google Cloud 亚太地区（东京）和 AWS 亚太地区（新加坡）区域的固定订阅计划中提供。
连接到 Redis 堆栈
> redis-cli -h 127.0.0.1 -p 6379
Load a library
Use the TFUNCION LOAD command to create a new library in your Redis instance.
127.0.0.1:6379> TFUNCTION LOAD "#!js api_version=1.0 name=myFirstLibrary\n redis.registerFunction('hello', ()=>{ return 'Hello World'})"
OK
When the library is created successfully, an OK response is returned. Run the TFUNCTION LIST command to confirm your library was added to Redis.
> TFUNCTION LIST
1) 1) "api_version"
2) "1.0"
3) "cluster_functions"
4) (empty list or set)
5) "configuration"
6) "null"
7) "engine"
8) "js"
9) "functions"
10) 1) "hello"
11) "keyspace_triggers"
12) (empty list or set)
13) "name"
14) "myFirstLibrary"
15) "pending_async_calls"
16) (empty list or set)
17) "pending_jobs"
18) "0"
19) "stream_triggers"
20) (empty list or set)
21) "user"
22) "default"
The TFCALL command is used to execute the JavaScript Function. If the command fails, an error will be returned.
127.0.0.1:6379> TFCALL myFirstLibrary.hello 0
"Hello World"
To update the library run the TFUNCTION LOAD command with the additional parameter REPLACE.
127.0.0.1:6379> TFUNCTION LOAD REPLACE "#!js api_version=1.0 name=myFirstLibrary\n redis.registerFunction('hello', ()=>{ return 'Hello World updated'})"
OK
Uploading an external file
Use the redis-cli command to upload JavaScript from an external file. The file needs to contain the header, which contains the engine identifier, the API version, and the library name: #!js api_version=1.0 name=myFirstLibrary.
#!js api_version=1.0 name=lib
redis.registerFunction('hello', ()=> {
return 'Hello from an external file'
})
Use the redis-cli -x option to send the file with the command and use the TFUNCTION LOAD REPLACE to replace the inline library with the one from the main.js file.
redis-cli -x TFUNCTION LOAD REPLACE < ./main.js
Creating triggers
Functions within Redis can respond to events using keyspace triggers. While the majority of these events are initiated by command invocations, they also include events that occur when a key expires or is removed from the database.
For the full list of supported events, please refer to the Redis keyspace notifications page.
The following code creates a new keyspace trigger that adds a new field to a new or updated hash with the latest update time.
Load the code in your database:
TFUNCTION LOAD REPLACE "#!js name=myFirstLibrary api_version=1.0\n
function addLastUpdatedField(client, data) {
if(data.event == 'hset') {
var currentDateTime = Date.now();
client.call('hset', data.key, 'last_updated', currentDateTime.toString());
}
}
redis.registerKeySpaceTrigger('addLastUpdated', 'fellowship:', addLastUpdatedField);" // Register the KeySpaceTrigger 'AddLastUpdated' for keys with the prefix 'fellowship' with a callback to the function 'addLastUpdatedField'
Add a new hash with the required prefix to trigger our function.
127.0.0.1:6379> HSET fellowship:1 name "Frodo Baggins" title "The One Ring Bearer"
Check if the last updated time is added to the example.
127.0.0.1:6379> HGETALL fellowship:1
1) "name"
2) "Frodo Baggins"
3) "title"
4) "The One Ring Bearer"
5) "last_updated"
6) "1693238681822"
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