Nestjs- Got 'undefined' as output while fetching data from mongodb in json format

Question

I am trying to fetch name and price property of a collection from MongoDB and I got output like this.

When I fetched name property then it shows correct value, but when I fetched price property then I got undefined value.

Note: i don't want to fetch all the properties which available on total. i just want to fetch price property of an object which is on first index of an array

Here is the code of service-:

async total(){
    const total= await this.usersmodel.find().exec()
    try{
        //return total[0].name
        console.log(total[0].name)
        console.log(total[0].price)
    }
    catch(error){
        return error.message
    }
}

Here is the code of controller-:

@Post('total')
async total(){
    return this.usersService.total();
}
}

if i use console.log(total) then i get all the objects of array, but i want to fetch only price from object which is present on 0 index of array. — sahil
– sahil, Commented May 19, 2020 at 11:01

Jeremy Thille · Accepted Answer · 2020-05-19 11:11:15Z

1

You're not returning any data from the service. You need to return what you fetched from Mongo.

async total(){
    const total= await this.usersmodel.find().exec()
    return total;
}

or

async total(){
    return await this.usersmodel.find().exec()
}

If you want to select only one field like price, use .select("price"). Or .select("name price") if you want more than one.

Also add .lean() to get raw data and not some Mongoose weirdo. Currently you're not getting JSON, but an array of Mongoose weirdos. By weirdo I mean stupid Mongoose objects, often immutable, with hidden keys and methods, that look like simple JSON but are absolutely not. .lean() will give you simple JSON. And it's faster.

usersmodel.find().select("price").lean().exec()

edited May 19, 2020 at 11:11

answered May 19, 2020 at 10:54

Jeremy Thille

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1 Comment

sahil Over a year ago

If i used your method then i'll get all the properties of document but i want only specific property that is price and nothing else. in screenshot i just trying to tell you my issue us that if i fetch name then it works properly but when am trying to fetch price its shows undefined

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