Error on callback when running a recursion function using async

Question

I try to execute a recursion through a tree, in order to exec node_func for each node in the tree. node_func also returns the next values in the tree under [values].

I use async.eachSeries which get a list of the nodes in the next level of the tree. The function runs successfully over the first branch of the tree, but at the leaf where I have the stop condition, I try to call the callback but it's undefined.

The code:

function clone(a) {
   return JSON.parse(JSON.stringify(a));
}
var searchNext = function(params, callbackSN){
    var seParams = clone(params);
    node_func(seParams,function(searchRes){
        //Stop Condition - return
        if (searchRes["nextFeature"] != 1){
            return callbackSN(); //Stop Condition
        }
        var values = searchRes["values"]
        var paramsArr = []
        for (var i = 0; i < values.length; i++) {
            var seParams2 = clone(seParams);
            seParams2["value"].push(values[i]["value"])
            paramsArr.push(seParams2)               
        };

        async.eachSeries(paramsArr, searchNext, function(err){
            return callbackSN(err)
        });         
    })
}

//init search
var params = {"value" :[]}
searchNext(params,console.log)

When I run it, it runs over the first branch, and when it gets to the "Stop Condition" I get the following error:

TypeError: undefined is not a function

Pointing to the line:

return callbackSN(); //Stop Condition

At the Stop Condition

Víctor Iniesta · Accepted Answer · 2014-12-28 16:06:03Z

1

In the line

return callback(err)

You are invoking the callback function, but it is not defined in your code. I guess you want to call the callbackSN function.

return callbackSN(err)

answered Dec 28, 2014 at 16:06

Víctor Iniesta

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3 Comments

skme Over a year ago

You are right. I have updated the code. But, still, it doesn't get there. As I wrote it fails on the "Stop Condition" line.

Víctor Iniesta Over a year ago

It is difficult to see where the problem is, because I do not know what the rest of the code does (as the node_func function) Could you post all the code?

skme Over a year ago

I'm pretty sure that the node_func is irrelevant, but I will try to create a sample function I can easily share.

skme · Accepted Answer · 2014-12-28 17:23:09Z

I had an error in the original code :

function clone(a) {
   return JSON.parse(JSON.stringify(a));
}
var searchNext = function(params,db, callbackSN){
    var seParams = clone(params);
    node_func(seParams,db,function(searchRes){
        //Stop Condition - return
        if (searchRes["nextFeature"] != 1){
            return callbackSN(); //Stop Condition
        }
        var values = searchRes["values"]
        var paramsArr = []
        for (var i = 0; i < values.length; i++) {
            var seParams2 = clone(seParams);
            seParams2["value"].push(values[i]["value"])
            paramsArr.push(seParams2)               
        };

        async.eachSeries(paramsArr, searchNext, function(err){
            return callbackSN(err)
        });         
    })
}

//init search
var params = {"value" :[]}
searchNext(params,console.log)

The second variable "db" at node_func cannot be called from the async, so it made the confusion.

I added the "db" variable at the parent function as a local variable.

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