sort query for array structure in mongodb

Question

I have a document having array structure in MongoDB. How can I sort the array element in ascending order?

The below is the Input:

{
    "id": 1,
    "name": "sanjay",
    "address": "Odisha",
    "shoes": [
        {
            "brand": "puma",
            "size": "10"
        },
        {
            "brand": "bata",
            "size": "11"
        },
        {
            "brand": "rebook",
            "size": "9"
        },
        {
            "brand": "adidas",
            "size": "7"
        },
        {
            "brand": "bata",
            "size": "8"
        }
    ]
}

Can anyone help me to get a query to sort my all array element in ascending order of the key "size"?

The below is the required output.

{
    "id": 1,
    "name": "sanjay",
    "address": "Odisha",
    "shoes": [
        {
            "brand": "adidas",
            "size": "7"
        },
        {
            "brand": "bata",
            "size": "8"
        },
        {
            "brand": "rebook",
            "size": "9"
        },
        {
            "brand": "puma",
            "size": "10"
        },
        {
            "brand": "bata",
            "size": "11"
        }
    ]
}

Could you please help me to find out the exact query?

Regards, Sanjay

This post answers your questions. You need to use the aggregation feature to unwind the array and then sort it. http://stackoverflow.com/questions/13449874/how-to-sort-array-inside-collection-record-in-mongodb — sunny, Jul 18 '15 at 13:46

Vishwas · Answer 1 · 2015-07-19T03:51:33.297

In your sample data, shoes.size is a string type. Before sorting, you need to change it to Int. You can use following query to do it.

db.collection.find().forEach(function(data) {
    for (var ii = 0; ii < data.shoes.length; ii++) {
    printjson(data._id);
    print(data.shoes[ii].size);
    db.shoe.update({
        "_id": data._id,
        "shoes.size": data.shoes[ii].size
    }, {
        "$set": {
            "shoes.$.size": parseInt(data.shoes[ii].size)
        }
    });
    }
});

After changing it use aggregation to sort shoes array by following query:

db.collection.aggregate({
    $unwind: "$shoes"
}, {
    $sort: {
    "shoes.size": 1
    }
}, {
    $group: {
    _id: "$_id",
    "shoes": {
        "$push": "$shoes"
    },
    "name": {
        $first: "$name"
    }
    }
}).pretty()

Edit

If you want to select for specific brand then add criteria in match condition.

db.collection.aggregate({
    $unwind: "$shoes"
}, {
    $match: {
    "shoes.brand": "bata"
    }
}, {
    $sort: {
    "shoes.size": 1
    }
}, {
    $group: {
    _id: "$_id",
    "shoes": {
        "$push": "$shoes"
    },
    "name": {
        $first: "$name"
    }
    }
}).pretty()

Vishwas could you please tell how could I find only matching array element in mongoDB. for example I want only array element in shoes whose brand is "bata". — Sanjayakumar Sahu, Jul 18 '15 at 17:41

sort query for array structure in mongodb

1 Answers1