Use lean in mongoose with callback

Question

I am trying to use lean in my mongoDB query but the problem I am facing is that I don't use .exec() method. I use callback implementation like below

model.find({user_id: mobile_no }, {'_id':0, 'type':1}, {sort: {dateTime: -1}, skip: page*page_size, limit: page_size + 1}, function(err, docs) {
     if (err) {
                
     } else {

     }
});

but in most documentation,everyone uses lean with .exec() like below

.lean().exec()

Can anyone please tell me how can I use lean using my callback implementation or I would have to use .exec() implementation in order to use it.

robertklep · Accepted Answer · 2017-05-15 09:47:14Z

1

You can use both .exec() and callbacks:

model.find(...).lean().exec(function(err, docs) {
  ...
});

See also the documentation, where one of the examples does the same.

answered May 15, 2017 at 9:47

robertklep

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6 Comments

Prakash Kumar Over a year ago

yes but as i am not using exec() can i use lean() without using exec() because otherwise i will have to change code everywhere just because of exec().

robertklep Over a year ago

I don't understand: you already have to change your code everywhere because you want to use .lean(), so what's the issue with adding an additional .exec()? Like my answer states: you can still use callbacks using .exec(), you don't have to use promises if you don't want to.

Prakash Kumar Over a year ago

ok thanks i just want to use my syntax, there is no extra problem thanks anyways.

Prakash Kumar Over a year ago

actually time taken by query is still little bit same, there is no significant difference coming ?? Can you tell me why this is hapening.

robertklep Over a year ago

My guess would be that your query just is slow, which lean won't solve (it only skips the step where Mongoose converts the MongoDB results into Mongoose documents).

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userProfile · Accepted Answer · 2018-08-10 12:58:59Z

0

model.find({user_id: mobile_no }, {'_id':0, 'type':1}, {sort: {dateTime: -1}, skip: page*page_size, limit: page_size + 1}, function(err, docs) {
     if (err) {

     } else {

     }
}).lean();

You have to write .lean() at the end of the query :3

answered Aug 10, 2018 at 12:58

userProfile

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