how to get all negative value document for particular user using express.js with mongodb?

Question

i have all user data which is inserted in mongodb.

[
{

    "user_id": "1",
    "name": "aaaa",
    "value": -10
  }, {

    "user_id": "2",
    "name": "bbbb",
    "value": 30

  }, {
    ,
    "user_id": "1",
    "name": "aaaa",
    "value": 310

  }, {

    "user_id": "2",
    "name": "bbbb",
    "value": -15
  }, {

    "user_id": "1",
    "name": "aaaa",
    "value": -100

  }, {

    "user_id": "3",
    "name": "cccc",
    "value": 390

  }]

how to do query for my requirment? in my document some user contaning value in negative . for example user_id = 1 contaning two negative value object i need to find out using query how can i modify my code?

User.findOne({user_id: '1'},function(err, user) { 
    if (err) return next(err);
    if (!user) return res.status(401).send('Unauthorized');
    res.json(user);
    });

please try this one *User.find( {user_id:'1', value: { $lt: 1 } } )* — KARTHIKEYAN.A, Nov 07 '16 at 06:38

score 1 · Accepted Answer · answered Nov 07 '16 at 07:50

To get multiple document use find instead of findOne. When you use find you get the output as array of objects. You can try the below code

User.find({user_id: '1' ,value : {$lt : 0}},function(err, users) { 
    if (err) return next(err);
    res.json(users);
});

score 1 · Answer 2 · answered Nov 07 '16 at 09:03

If you just need to find all entries with negative values, just specify value < 0 as your query criteria:

User.find({value : {$lt : 0}},function(err, users) { 
  if (err) return next(err);
  if (!users || users.length) {
    return res.status(401).send('Unauthorized');
  }
  res.json(users);
});

score 0 · Answer 3 · answered Nov 07 '16 at 09:45

Try this

By referring your sample schema, it is array of documents of user_id's

Use $unwind to seperate the docs from array and filter the documents by using given user_id and whose value is negative.

Sample document

{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : [
                {
                        "user_id" : "1",
                        "name" : "aaaa",
                        "value" : -10
                },
                {
                        "user_id" : "2",
                        "name" : "bbbb",
                        "value" : 30
                },
                {
                        "user_id" : "1",
                        "name" : "aaaa",
                        "value" : 310
                },
                {
                        "user_id" : "2",
                        "name" : "bbbb",
                        "value" : -15
                },
                {
                        "user_id" : "1",
                        "name" : "aaaa",
                        "value" : -100
                },
                {
                        "user_id" : "3",
                        "name" : "cccc",
                        "value" : 390
                }
        ]
}

db.collection.aggregate([{$unwind:"userArray"}]);

The result of unwind on above data would be

{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "1",
                "name" : "aaaa",
                "value" : -10
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "2",
                "name" : "bbbb",
                "value" : 30
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "1",
                "name" : "aaaa",
                "value" : 310
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "2",
                "name" : "bbbb",
                "value" : -15
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "1",
                "name" : "aaaa",
                "value" : -100
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "3",
                "name" : "cccc",
                "value" : 390
        }
}

Then apply the condition of that is user_id and value is negative. For this we can use $match together with $and (since we have two conditions value and id)

db.collection.aggregate([{$unwind:"$userArray"}, {$match:{$and: [{"userArray.value":{$lte:0}}, {"userArray.user_id":"1"}]}} ]);

for user_id: 1 the query result is

{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "1",
                "name" : "aaaa",
                "value" : -10
        }
}
{
        "_id" : ObjectId("582032556772b7cb0ff85721"),
        "userArray" : {
                "user_id" : "1",
                "name" : "aaaa",
                "value" : -100
        }
}

With this result you have to iterate it in your service layer and work on the other desired results.

Hope it helps!

how to get all negative value document for particular user using express.js with mongodb?

3 Answers3

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