Dynamic mongodb query generation with Node.js driver

Question

Dynamic mongodb query generation with Node.js driver

I am using the Node.js driver for MongoDB and have no trouble construction query objects outside of the call to find() until I attempt to introduce an $or construct into the mix.

I am attempting to dynamically generate the query because I have a variable number of parameters and would prefer to NOT have as many calls to collection.find as I have parameters.

To that end I am

A query as simple as:

var query = {};
query['name'] = 'Steve';
query['date_created'] = '<some date>';

mongo_collection.find(query, function(err, c) {});

Works perfectly.

However, when I attempt to use $or the whole process falls apart.

I have tried each of the following with no joy:

var query = {};

1) query[$or] = [ { 'field' : 'value1' }, { 'field' : 'value2' } ]; query['date_created'] = '';

2) query = { $or : [ { 'field' : 'value1' }, { 'field' : 'value2' } ] }; query['date_created'] = '';

3) query = eval("[ { 'field' : 'value1' }, { 'field' : 'value2' } ]"); query['date_created'] = '';

In every case the $or is wrapped in quotes (honestly I am not sure if this is the problem or not...) and the query fails.

Is there any way to accomplish this?

Thanks for any help you can offer!

r/Steve

javascript
node.js
mongodb
dynamic

Answer 1

Here is how you can do it (there are probably multiple ways):

var query = {};

query["$or"]=[];
query["$or"].push({"field":"value1"});
query["$or"].push({"field":"value2"});
query["date_created"]="whatever";

query
{
    "$or" : [
        {
            "field" : "value1"
        },
        {
            "field" : "value2"
        }
    ],
    "date_created" : "whatever"
}

Now you should be able to run db.collection.find(query)