User functions
Execute JavaScript functions via TFCALL or TFCALLASYNC
All TFCALL command arguments that follow the function name are passed to the function callback. The following example shows how to implement a simple function that returns the value of a key of type string or hash:
#!js api_version=1.0 name=lib
redis.registerFunction('my_get', function(client, key_name){
if (client.call('type', key_name) == 'string') {
return client.call('get', key_name);
}
if (client.call('type', key_name) == 'hash') {
return client.call('hgetall', key_name);
}
throw "Unsupported type";
});
Example of running the preceding function:
127.0.0.1:6379> set x 1
OK
127.0.0.1:6379> TFCALL lib.my_get 1 x
"1"
127.0.0.1:6379> hset h a b x y
(integer) 2
127.0.0.1:6379> TFCALL lib.my_get 1 h
1) "a"
2) "b"
3) "x"
4) "y"
It is also possible to get all the function arguments as a JS array. This is how we can extend the above example to accept multiple keys and return their values:
#!js api_version=1.0 name=lib
redis.registerFunction('my_get', function(client, ...keys){
var results = [];
keys.forEach((key_name)=> {
if (client.call('type', key_name) == 'string') {
results.push(client.call('get', key_name));
return;
}
if (client.call('type', key_name) == 'hash') {
results.push(client.call('hgetall', key_name));
return;
}
results.push("Unsupported type");
}
);
return results;
});
Run example:
127.0.0.1:6379> TFCALL foo.my_get 2 x h
1) "1"
2) 1) "a"
2) "b"
3) "x"
4) "y"