how to force execution of requests inside async.each with nodejs?

Question

I have a async.each that iterates an array and for every element inside the array it execute a function "check" that has a request inside. This is the code but when I run it I see from the debugger that node doesn't execute the check function and it block its execution.

async.each(array,
  function(v_page, callback){
    if(v_page.url.length>=5){
      internals.check(v_page.url,array2, function (body) {
        callback();
      });
    }
  },
  function(err){
    internals.calls(var1,var2,var3);
});

I tried with a normal for loop but it jump at the internals.calls function without execute the internals.check function for the async nature of node. So how can i force the execution of the check function?

This is the code of the check function:

internals.check = (url,array2,cb) => {
  request(url, function(err, recordset) {
    if(err){
      cb(array2);
    }else {
      //some stuffs
      cb(array2)
    }
  });
};

alexmac · Accepted Answer · 2017-08-31 15:00:20Z

4

You call callback only when v_page.url.length >= 5, but you need to do that for each element:

async.each(array, function(v_page, callback) {
 if(v_page.url.length >= 5) {
   internals.check(v_page.url,array2, function(body) {
     callback();
   });
 } else {
   callback(); <== call callback here, when condition is not met
 }
 ...

Another problem is that, you incorrectly call callback in internals.check. According Node.js notation, the first parameter of callback must be an error or null (async uses this notation). But in your case you call callback with array2 anyway:

internals.check = (url, array2, cb) => {
  request(url, function(err, recordset) {
    if (err) {
      cb(err); // <== pass error here
    } else {
      cb(null, array2); // <== no error, so first parameter is null, the second is data
    }
  });
};

edited Aug 31, 2017 at 15:00

answered Aug 31, 2017 at 14:46

alexmac

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6 Comments

Graziano Dimatteo Over a year ago

Thanks, I added it but nothing changed and above all I did not solve the problem... It doesn't execute the check function.

alexmac Over a year ago

Updated the answer, you have a bug in internals.check function.

Graziano Dimatteo Over a year ago

ok I fix the callback bug but from the debugger i saw that it enters inside the check function and when it arrives to request, it jump to the end of the function so it doesn't see the callback cb. I think that this is the problem.

alexmac Over a year ago

Of course it jumps to the end, because request is `asynchronous_ function, it returns immediately and later, when data is loaded, calls callback.

Graziano Dimatteo Over a year ago

so there isn't any solution?

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