mongo query for multiple condition

Question

I have data,

var data = [{name: 'n1', age: 22}, {name: 'n1', age: age: 11}, {name: 'n2', age: age: 16}, {name: 'n3', age: 22}];

and I want to get data according to my multiple conditions:

condition 1:- var query = {name: 'n1', age: 22};

condition 2:- var query = {name = '', age: 22}

What I want with a single query:

If I run condition 1 then the result should be

[{name: 'n1', age: 22}].

and if I run condition 2, then the result should be

[{name: 'n1', age: 22}, {name: 'n3', age: 22} ].

Means for second condition, query should search only with age field.

That all I want to implement in one query.

I am doing like:

$query:{$and: [{name: query.name}, {age: query.age}]}

It works for first condition but not for second. How can achieve it in one query?

Answer 1

Code it up so that only the fields you're interested in are in the query:

let criteria = [];

if (query.name && query.name.length > 0) {
   criteria.push({ name: query.name });
}

if (query.age && query.age > 0) {
   criteria.push({ age: query.age });
}

criteria = criteria.length > 0 ? { $and: criteria } : {};

Now you can pass your criteria to the query.

Answer 2

You could create a query object that can be initialised based on the two conditions above. The following snippet demonstrates this:

Populate test collection

db.test.insert([
    {name: 'n1', age: 22}, 
    {name: 'n1', age: 11}, 
    {name: 'n2', age: 16}, 
    {name: 'n3', age: 22}
])

Initialise conditions

var criteria = {},
    condition = [
        {"name": query.name}, 
        {"age": query.age}
    ]; 

if (query.name !== "") { criteria["$and"] = condition; }
else { criteria["$or"] = condition; }

Test criteria for condition 1)

var query = {"name": "n1", "age": 22 }
printjson(criteria);
db.test.find(criteria);

Sample Output

{ "$and" : [ { "name" : "n1" }, { "age" : 22 } ] }

{ "_id" : ObjectId("56b341802ae7a05a8444cedc"), "name" : "n3", "age" : 22 }

Test criteria for condition 2)

var query = {"name": "", "age": 22 }
printjson(criteria);
db.test.find(criteria);

Sample Output

{ "$or" : [ { "name" : "" }, { "age" : 22 } ] }

{ "_id" : ObjectId("56b341802ae7a05a8444ced9"), "name" : "n1", "age" : 22 }
{ "_id" : ObjectId("56b341802ae7a05a8444cedc"), "name" : "n3", "age" : 22 }