Node JS Mongodb collection.find（）查询结果超出范围

Question

I wane collection.find() query result outside the queryfunctin

var fol;

  Folder
    .find({'parentid':id,'stats.archive':'0'})
    .lean()
    .exec(function(err, f_folder) {
        if(!err) {
          fol = f_folder;
        } 

    });

  console.log(fol); // I want query result here

Please, give me solutions why query does not return result outside function

Answer 1

The console.log() called outside the callback passed to the exec() will be executed before the exec() function return.

What you need to do, as @VsevolodGoloviznin said, is to call the console.log() inside the callback, like:

Folder
  .find({'parentid':id,'stats.archive':'0'})
  .lean()
  .exec(function(err, f_folder) {
    if(!err) {
      fol = f_folder;
      console.log(fol);
    }
  });

That will guarantee that your fol var will not be undefined .

What you could also do is to wrap the logic inside functions:

function findFolder(callback) {
  Folder
    .find({'parentid':id,'stats.archive':'0'})
    .lean()
    .exec(function(err, f_folder) {
      if(!err) {
        fol = f_folder;
        callback(fol);
      }
    });
}

function logResult(result) {
  console.log(result);
}

findFolder(logResult);