CommandReader

根据命令运行 RedisGears 函数。

Redis 堆栈

这CommandReader允许您在以下情况下根据命令运行 RedisGears 函数：

  1. 将CommandReader到GearsBuilder.CreateGearsBuilder()函数。

  2. 调用register()功能。

  3. 跑RG.JEXECUTE以注册您的代码。

  4. 用RG.TRIGGER要按命令运行代码，请执行以下作：

    RG.TRIGGER <Trigger name> [arg1 arg2 ...]

Parameters

Name Type Description
trigger string The command name that triggers the registered RedisGears functions to run

Output records

Outputs a record with the command trigger's name and arguments.

Example

The following example shows how to create a custom command to update an item's stock. It also adds a timestamp to track when the last restock occurred.

Add a hash to the database that represents an inventory item:

redis> HSET inventory:headphones:1 color "blue" stock 5 price 30.00
(integer) 3

Example code:

// Create the reader that will pass data to the pipe
CommandReader reader = new CommandReader();
// Set the name of the custom command
reader.setTrigger("Restock");
        
// Create the data pipe builder
GearsBuilder.CreateGearsBuilder(reader).map(r-> {
    // Parse the command arguments to get the key name and new stock value
    String itemKey = new String((byte[]) r[1], StandardCharsets.UTF_8);
    String newStock = new String((byte[]) r[2], StandardCharsets.UTF_8);
        	
    // Update the item's stock and add a timestamp
    GearsBuilder.execute("HSET", itemKey , "stock", newStock,
        			"last_restocked", Long.toString(System.currentTimeMillis()));
        	
    return "OK restocked " + itemKey;
}).register();

After you register the previous code with the RG.JEXECUTE command, run RG.TRIGGER to test it:

redis> RG.TRIGGER Restock inventory:headphones:1 20
1) "OK restocked inventory:headphones:1"

The item now has the updated value for stock and a last_restocked timestamp:

redis> HGETALL inventory:headphones:1
1) "color"
2) "blue"
3) "stock"
4) "20"
5) "price"
6) "30.00"
7) "last_restocked"
8) "1643232394078"