How to do find in node and mongodb?

Question

This is my \'usergroups\' data

{
    \"_id\": {
        \"$oid\": \"58f7537ec422895572e988a1\"
    },
    \"name\": \"aaa\",
    \"groupname\": \"group north,gro         


        

Answer 1

You can simply get the groupname from the Usergroup, split it to array of two group name using str.split(',') and then query the Group for two groupname as follow:

    Usergroup.findOne({ mobilenumber: 0509867865 }, function(err, usergroup) {
        if (err) {
            return handleError(res, err);
        }
        if (!usergroup) {
            return res.status(404).send('Not Found');
        }
        console.log(usergroup.groupname);

        var groupname   = usergroup.groupname;
        var groups      = groupname.split(',');
        var messages    = {};

        for (var i = groups.length - 1; i >= 0; i--) {
            Group.find({ groupname: groups[i] }, function(err, group) {
                if (err) {
                    return handleError(res, err);
                }
                messages[group.groupname] = group.message;
            });
            if (i == 0) {
                return res.status(200).json(messages);
            }
        }

    });

Answer 2

You can use the below aggregation for 3.4 version.

The query will $match documents in the usergroups collection with the mobilenumber followed by $split to split the groupnames and $lookup the groupname in the groups collection for messages. Final step is to $unwind the mobile_group array to $project the messages for each groupname.

db.usergroups.aggregate([
    { $match: { mobilenumber:"0509867865" } },
    { $project: { groupname:{ $split: [ "$groupname", ',' ] }  } },
    { $lookup:
        {
          from: "groups",
          localField: "groupname",
          foreignField: "groupname",
          as: "mobile_group"
        }
   },
   {$unwind:"$mobile_group"},
   { $project : { groupname:"$mobile_group.groupname", "messages" : "$mobile_group.message" } }
])

Answer 3

You can use the $in operator:

Usergroup.findOne({
            mobilenumber: 0509867865
        },
        function(err, usergroup) {
            if (err) {
                return handleError(res, err);
            }
            if (!usergroup) {
                return res.status(404).send('Not Found');
            }
            console.log(usergroup.groupname);
        //group north ,group south
            Group.find({
                    groupname: { $in: usergroup.groupname.split(",") } 
                },
                function(err, group) {
                    if (err) {
                        return handleError(res, err);
                    }

                    return res.json(group);
                });
        });