How to assign global variables using Node.js and Redis with for loop?

Question

I am attempting to programmatically retrieve values from a Redis database in Node.js using a 'for' loop to iterate over GET requests. I am using the 'redis' node module. I am able to print the values of these requests to the server using console.log, however, I am not able to push each of these values to a global array for use in another node.js module. I am wondering if this is due to the 'global variables protection' aspect of Redis scripts. I'd also like to know if there is a workaround here.

redis-cli:

redis 127.0.0.1:6379> SET a "1"
OK
redis 127.0.0.1:6379> SET b "2"
OK
redis 127.0.0.1:6379> SET c "3"
OK

node.js:

var keys = ['a', 'b', 'c'];
var vals = [];
for(i=0; i<3; i++) {
    client.get(keys[i], function(err, reply) {
        console.log(reply);
        vals.push(reply);
    });
}
console.log(vals);

I would like for the vals array to output the values associated with a, b, and c...or 1, 2, and 3, respectively. Again, the intent is to use these values in another node module.

Is this an issue associated with global variables protection? Any obvious alternatives? Definitely feel like I am missing something obvious.

Answer 1

client.get is an async function. reply's are getting pushed to vals as expected, but not immediately. In near future they will be pushed to vals . So, when you try to log vals synchronously you will only get empty array.

With async.js , you could do something like this:

var vals;
var keys = ['a', 'b', 'c'];
var async = require('async');
async.map(keys, client.get, function(err, results) {
  vals = results;
  console.log(vals);//will print what you wanted.
});

But, anyway, you cannot share vals with other files by making it global. I suggest you to write asynchronous getter function for vals & make other files to call that function to get vals .