javascript - return Model.create(arr).exec() is not working in mongoose - Stack Overflow

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I heard that exec "returns a promise" so I'm using exec it do asynchronous calls. This question is inspired my other question. The mentator said my code is not working because :

You are using asynchronous code synchronously

I was trying to fix that by using the below code. Don't know if this code will make it not sync but I heard that promises help with that.

so I have this and I cannot create(save) the data but I can delete it. why cant I use the same pattern for create as i did for remove?

var Comp = require("./models/pany.js");
  var arr = [
    {name : "p1",industry : "industry1", ranking: 20},
    {name : "p2",industry : "industry2", ranking: 5},
    {name : "p3",industry : "industry3", ranking: 10}
  ]


Comp.find({}).exec()
    .then(function(docs){
        return Comp.remove({}).exec()
        .then(function(){
            console.log("deleted")
        })
    })
    .then(function(){
        return Comp.create(arr).exec()
        .then(function(data){
            console.log(data)
        })
    })

and can you help get to my original goal which was in my other question.

I heard that exec "returns a promise" so I'm using exec it do asynchronous calls. This question is inspired my other question. The mentator said my code is not working because :

You are using asynchronous code synchronously

I was trying to fix that by using the below code. Don't know if this code will make it not sync but I heard that promises help with that.

so I have this and I cannot create(save) the data but I can delete it. why cant I use the same pattern for create as i did for remove?

var Comp = require("./models/pany.js");
  var arr = [
    {name : "p1",industry : "industry1", ranking: 20},
    {name : "p2",industry : "industry2", ranking: 5},
    {name : "p3",industry : "industry3", ranking: 10}
  ]


Comp.find({}).exec()
    .then(function(docs){
        return Comp.remove({}).exec()
        .then(function(){
            console.log("deleted")
        })
    })
    .then(function(){
        return Comp.create(arr).exec()
        .then(function(data){
            console.log(data)
        })
    })

and can you help get to my original goal which was in my other question.

• javascript
• node.js
• mongodb
• mongoose

Share Improve this question Follow edited May 23, 2017 at 12:17 CommunityBot 111 silver badge asked May 18, 2016 at 20:35 jack blankjack blank 5,19577 gold badges4545 silver badges7575 bronze badges

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3 Answers 3

Sorted by: Reset to default 4

The then funtion does not return promise, the exec does!

So you need to do return Comp.remove({}).exec()

Comp.find({}).exec()
.then(function(docs){
    return Comp.remove({}).exec();
})
.then(function(result_of_remove){
    return Comp.create(arr).exec();
})
.then(function(result_of_create){
    ....
})

first of all you should confirm you mongoose version.

in older version:

Model.create(doc) returns a query object; call the exec method of the query will trigger the database operation and return a promise.

in new version (i am using 4.4.8) of mongoose Model.create(doc) and 'Model.remove(con)' returns a promise directly.

so check with your version to see if you need to remove some exec

last but not least add catch call to check if you got some errors, it helps when debug

Comp.find({}).exec()
.then(function(docs){
    return Comp.remove({}).exec();
})
.then(function(result_of_remove){
    return Comp.create(arr).exec();
})
.then(function(result_of_create){
    ....
})
.catch(function(error){
  console.log(error)
})

I normally use .exec() when I want to return a Promise when working with

Model.findOne(...).exec()

Model.create(...) returns a Promise.

The .exec() function does not exist for Model.create(...)

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