Mongoose/MongoDB dynamic where depend URL Parameters

Question

Using NodeJS with Mongoose and MongoDB for my back-end.

I am trying to do this (example):

controller.getUsersSearchAll = function(req, res){
    let last = req.query.last;
    let min = req.query.minPrice;
    let max = req.query.maxPrice;
    if(last && min && max){
        User.find()
            .where('last_name').equals(last)
            .where('age').gte(min).lte(max)
            .exec(function(err, result){
            res.json(result);
        });
    }else if(last){
        User.find()
            .where('last_name').equals(last)
            .exec(function(err, result){
            res.json(result);
        });
    }    
};

It works but in this way, it is static. The problem is when I have 10 conditions or more I had to apply many if conditions.

How to convert it to a dynamic way? Is there a smart way?

user2263572 · Accepted Answer · 2018-11-25 13:44:56Z

1

Why not just store your base query in a var and then add to it?

var query = User.find().where('last_name').equals(last)

// editing to show adding multiple where conditons
if(condition_1){
  query = query.where('age').gte(10)
}
if (condition_2){
  query = query.where('age').gte(50)
}
if (condition_3){
  query = query.where('age').gte(100)
}//...etc for any other where clauses you need to add

//Then exec your query and do something with the data
query.exec(function(err, data){})

edited Nov 25, 2018 at 13:44

answered Nov 25, 2018 at 13:31

user2263572

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4 Comments

Vasilis Greece Over a year ago

That was an example. If I had 10 conditions that solution is not applied in my case. In addition there is a possibility to search only by age and not with last_name.

user2263572 Over a year ago

If you have 10 conditions, you need to write the logic for each condition. There is no avoiding that. The point is to build the common part of the query statement and store it in a variable. Then you can add any condition that applies.

Vasilis Greece Over a year ago

Can you edit your answer with for each condition? Because I don't know what you mean exactly.

user2263572 Over a year ago

Answer updated. I'd also recommend checking out this answer to understand why this works. stackoverflow.com/questions/8300844/….

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