Programmatically build dynamic query with Mongoose

Question

I'm trying to build a search from input received from a form.

router.get('/data', function(req, res) {
    var firstName=req.body.firstName,
    lastName=req.body.lastName,
    companyName=req.body.companyName,
    email=req.body.email;
});

I'd like to build a query up from these values, but if the field has no value, I obviously don't want to include it in the search (searching for "" would change the results)

I've tried a couple different things, like building a string to place in:

mongoose.model('customers').find({QUERY STRING WOULD GO HERE} ,function(err, data) {
    if (err) return console.error(err);
    console.log(data);
});

But that doesn't seem to work properly. I also tried "stacking" search queries like this:

if(firstName !="") {
    mongoose.model('customers').find({firstName: firstName})
}

and then executing the search like this:

mongoose.model('customers').exec(function(err, customer){
    console.log(customer);
});

But that causes 500 errors (and I'm not sure if there's any more info I can get from them).

Please help a Newbie dynamically build a mongoose search query :(

Instead of a query string, have you tried constructing a query object? (if you're new to javascript other languages call it "hash" or "map" or "array") — slebetman
– slebetman, Commented Apr 6, 2015 at 6:27
@slebetman You're absolutely right. I looked up how to create an object, but just wasn't doing it properly :( — Stephen Bailey
– Stephen Bailey, Commented Apr 6, 2015 at 20:27

Sudhir Bastakoti · Accepted Answer · 2015-04-06 06:32:11Z

38

try creating query object, like:

//generate query object based on availability of value 
var query = {};
if( your_variable !== "" ) {
    query["some_key"] = your_variable;
}
if( your_second_variable !== "" ) {
    query["some_other_key"] = your_second_variable;
}
mongoose.model('customers').find(query, function(err, c) {
    //do something
});

answered Apr 6, 2015 at 6:32

Sudhir Bastakoti

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3 Comments

Stephen Bailey Over a year ago

I did exactly this and it worked! I was trying to make an object wrong the whole time! Thanks for helping me out!

RamBen Over a year ago

Hi DemoUser, If I want to put the 'in' checking how to use the above one, means I want check this {usernames: {$in:['x','y','z']}} . In this case what is first variable and second variable.

sandyiit Over a year ago

@RamBen - you can use: query["usernames"] = {$in:['x','y','z']}}

Tomasz Gałkowski · Accepted Answer · 2017-03-27 16:48:27Z

13

For people using newer JavaScript (and especially on Node.js 7.6.0+ or Babel).

The best way I found for programmatically building queries (based on if clauses etc.) is using the Query and the alternative syntax.

let query = PersonModel().find();

if (isMale) {
    query.where('sex', 'male'); 
} else {
    query.where('sex', 'female');
}

query.where('alive', true);

// and then to run the query
const result = await query.exec();

Note the async/await usage here. It's working perfectly on Node.js 7.6.0+. If you don't want to use async/await you can just use Promises like so:

query.exec().then(result => {
    // result has your... results
});

answered Mar 27, 2017 at 16:48

Tomasz Gałkowski

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2 Comments

Stephen Bailey Over a year ago

Thanks for the input! My usecase is a lot simpler than that, but I appreciate it either way! I'm sure someone will get good use of it!

Jha Nitesh Over a year ago

Before using $where make sure you consider these points,mongodb.com/docs/manual/reference/operator/query/where

Talha Awan · Accepted Answer · 2016-10-25 18:46:28Z

10

To avoid checking each parameter independently you can loop through them.

var query = {};
for(var key in req.body){ //could also be req.query and req.params
  req.body[key] !== "" ? query[key] = req.body[key] : null;
}

mongoose.model('customers').find(query, function(err, customers){

})

answered Oct 25, 2016 at 18:46

Talha Awan

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1 Comment

Stephen Bailey Over a year ago

This is pretty helpful, thanks! I've done this in a couple other places in my app and it's been pretty helpful!

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