Laravel collection get unique order by date

Question

I have a collection which I have been able to sort to return to me sorted by user id and by date, the problem being that I need to get a unique user with the most current date, but I can't get it. This is my json:

{
    "168": {
        "created_at": "2019-01-23 12:40:26",
        "user_id": 1,
        "from": "form",
        "name": "Pedro",
        "lastname": "Pretgar",
        "email": "pedro@demo.com"
    },
    "154": {
        "created_at": "2019-06-28 13:34:21",
        "user_id": 1,
        "from": "form",
        "name": "Pedro",
        "lastname": "Pretgar",
        "email": "pedro@demo.com"
    },
    "167": {
        "created_at": "2019-01-31 17:33:26",
        "user_id": 8,
        "from": "gmail",
        "name": "Lilian",
        "lastname": "Houster",
        "email": "lilian@demo.com"
    },
    "156": {
        "created_at": "2019-06-08 12:14:42",
        "user_id": 14,
        "from": "form",
        "name": "Jhon",
        "lastname": "Cobra",
        "email": "jhon@demo.com"
    },
    "38": {
        "created_at": "2019-07-21 21:22:18",
        "user_id": 14,
        "from": "form",
        "name": "Jhon",
        "lastname": "Cobra",
        "email": "jhon@demo.com"
    },
    "81": {
        "created_at": "2019-09-25 10:24:34",
        "user_id": 14,
        "from": "form",
        "name": "Jhon",
        "lastname": "Cobra",
        "email": "jhon@demo.com"
    }
}

I need this result:

{

    "154": {
        "created_at": "2019-06-28 13:34:21",
        "user_id": 1,
        "from": "form",
        "name": "Pedro",
        "lastname": "Pretgar",
        "email": "pedro@demo.com"
    },
    "167": {
        "created_at": "2019-01-31 17:33:26",
        "user_id": 8,
        "from": "gmail",
        "name": "Lilian",
        "lastname": "Houster",
        "email": "lilian@demo.com"
    },
    "81": {
        "created_at": "2019-09-25 10:24:34",
        "user_id": 14,
        "from": "form",
        "name": "Jhon",
        "lastname": "Cobra",
        "email": "jhon@demo.com"
    }
}

I have tried, sorting by date and then getting the unique value, the problem is that I don't know how to sort first by the most current date and then get the unique value.

$tmp = $users->sortBy(function($user) {
            return [$user->user_id, $user->created_at];
        })->unique('user_id');

Answer 1

you can try

$users->orderBy('created_at', 'desc')
     ->orderBy('user_id', 'asc')
     ->groupBy('user_id')
     ->get();

Answer 2

This code will works :

$users
    ->sortByDesc('created_at')
    ->unique('user_id');

Sort by desc method : https://laravel.com/docs/7.x/collections#method-sortbydesc

Unique method : https://laravel.com/docs/7.x/collections#method-unique

It will return this array :

    81 => { #9 ▼
      +"created_at": "2019-09-25 10:24:34"
      +"user_id": 14
      +"from": "form"
      +"name": "Jhon"
      +"lastname": "Cobra"
      +"email": "jhon@demo.com"
    }
    154 => {#5 ▼
      +"created_at": "2019-06-28 13:34:21"
      +"user_id": 1
      +"from": "form"
      +"name": "Pedro"
      +"lastname": "Pretgar"
      +"email": "pedro@demo.com"
    }
    167 => {#6 ▼
      +"created_at": "2019-01-31 17:33:26"
      +"user_id": 8
      +"from": "gmail"
      +"name": "Lilian"
      +"lastname": "Houster"
      +"email": "lilian@demo.com"
    }

If you want the exact array as you have, sorted by the most recent date and the user_id I guess, you can chain with another sort method with the user_id :

$users
    ->sortByDesc('created_at')
    ->sortBy('user_id')
    ->unique('user_id');

It will return this array :

154 => {#5 ▼
  +"created_at": "2019-06-28 13:34:21"
  +"user_id": 1
  +"from": "form"
  +"name": "Pedro"
  +"lastname": "Pretgar"
  +"email": "pedro@demo.com"
}
167 => {#6 ▼
  +"created_at": "2019-01-31 17:33:26"
  +"user_id": 8
  +"from": "gmail"
  +"name": "Lilian"
  +"lastname": "Houster"
  +"email": "lilian@demo.com"
}
81 => {#9 ▼
  +"created_at": "2019-09-25 10:24:34"
  +"user_id": 14
  +"from": "form"
  +"name": "Jhon"
  +"lastname": "Cobra"
  +"email": "jhon@demo.com"
}