Merge mongodb arrays in one array with aggregation

Question

I want to display the following result

[
  {
    "MergedTabs": [1,2,3,4,5,6],
    "name": "John"
  }
]

from the collection below

[
  {
    "name":"John",
    "tab":[1,2,3]
  },
  {
    "name":"John",
    "tab":[4,5,6]
  }
]

I tried the query below but I doesn't display what I want

db.collection.aggregate([
  {
    "$group": {
      "_id": "$name",
      "MergedTabs": {
        "$push": "$tab"
      }
    }
  },
    {
    "$project": {
      "name": "$_id",
      "MergedTabs": 1
    }
  }
])

Any ideas how to solve it please ? Thanks

Answer 1

    db.collection.aggregate([
  {
    $unwind: "$tab"
  },
  {
    $group: {
      _id: "$name",
      mergedTab: {
        $push: "$tab"
      }
    }
  },
  {
    $project: {
      name: "$_id",
      mergedTab: 1,
      _id: "$$REMOVE"
    }
  }
])