MongoDB - Aggregation - To get unique items in array

Question

Here\'s my MongoDB collection:

{
    \"_id\" : ObjectId(\"515d8f53175b8ecb053425c2\"),
    \"category\" : \"Batteries\",
    \"products\" : [
        {
              


        

Answer 1

After few more tries, I had solved this. Here's the commands:

db.xyz.aggregate( {$project: {a: '$products.item'}}, 
    {$unwind: '$a'}, 
    {$unwind: '$a'}, 
    {$group: {_id: 'a', items: {$addToSet: '$a'}}});

and

db.xyz.aggregate( {$project: {category: 1, a: '$products.item'}}, 
    {$unwind: '$a'}, 
    {$unwind: '$a'}, 
    {$group: {_id: '$category', items: {$addToSet: '$a'}}});