node_redis - embarrassingly easy question

[Aaron Reabow]

I have the feeling this might be really dumb.  I am trying to obtain the value of a list's length from redis.

It is returning correctly inside the anonymous function (if I console.log it), I just can't for the life of me seem to access outside of that function.

Here I have set a local variable - len - and tried to assign a value for it inside the function.

I wouldn't expect it to work like this, because I should set a global variable len instead.

The strange thing is that neither approach works.  Even if the global variable did the trick, it seems remiss to be using a global variable for something so trivial.

Any ideas on a solution?  Here is my code:

var len = 0

redis.llen("chatRecord", function (err, length) {

            log('length from llen is: ' + length)

len = length

        });

[Aaron Reabow]

Right.  So I forgot about non blocking.  The call to redis will enough time for js to move on and execute down the page.

I had the feeling this was going to be embarrassing :)

[Christopher Mina]

At what point outside of the redis callback are you checking the value of "len"? As this, like most calls in JS, is async, you must wait for the call to complete and then notify your calling method via a callback function, watcher system, event system, etc. What you can't do is simply reference the Len value beneath your redis call and expect it to be set.

Good luck
Chris

[Adam Reynolds]

Have a look at Promises or Observables. 

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[Christopher Mina]

It happens! Glad to see people involved in JS at any level. 

Chris

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