雄辩的-按月，年和分页分组

Question

I am trying to list entries in a table by Month, Year:

• May, 2015
  • Item 1
  • Item 2
  • Item 3
• June, 2015
  • Item 1
  • etc..

I have achieved this with the following code but I would also like to paginate the results . I have tried many different things but none of them seem to work, I am using Laravel 5.

$events = App\Events->orderBy('start', 'asc')->get()->groupBy(function($date) {
            return $date->start->format('F, Y');
        });

Here is the output for the above query:

{
    "April, 2015": [
        {
            "id": "10",
            "event_type_id": "1",
            "user_id": "1",
            "title": "Testing",
            "slug": "testing",
            "start": "2015-04-23 17:00:00",
            "end": "2015-04-23 17:40:00",
            "description": "<h1>MEETING!</h1><p>Let's try this in HTML!<br></p>",
            "created_at": "2015-04-19 14:18:33",
            "updated_at": "2015-04-21 22:07:41",
            "type": {
                "id": "1",
                "name": "General",
                "slug": "general",
                "created_at": "2015-04-18 11:24:00",
                "updated_at": "2015-04-18 11:24:04"
            }
        }
    ],
    "May, 2015": [
        {
            "id": "12",
            "event_type_id": "1",
            "user_id": "1",
            "title": "Test Event",
            "slug": "test-event",
            "start": "2015-05-15 18:00:00",
            "end": null,
            "description": "<p>This is a test event with just a start time</p>",
            "created_at": "2015-04-21 14:59:56",
            "updated_at": "2015-05-02 18:37:53",
            "type": {
                "id": "1",
                "name": "General",
                "slug": "general",
                "created_at": "2015-04-18 11:24:00",
                "updated_at": "2015-04-18 11:24:04"
            }
        },
        {
            "id": "9",
            "event_type_id": "1",
            "user_id": "1",
            "title": "Monthly Meeting",
            "slug": "monthly-meeting",
            "start": "2015-05-23 14:00:00",
            "end": "2015-04-16 20:00:00",
            "description": "<p>It's a long monthly meeting!</p>",
            "created_at": "2015-04-19 13:13:45",
            "updated_at": "2015-05-03 08:45:56",
            "type": {
                "id": "1",
                "name": "General",
                "slug": "general",
                "created_at": "2015-04-18 11:24:00",
                "updated_at": "2015-04-18 11:24:04"
            }
        }
    ],
    "June, 2015": [
        {
            "id": "11",
            "event_type_id": "1",
            "user_id": "1",
            "title": "Another Meeting Saved",
            "slug": "another-meeting-saved",
            "start": "2015-06-19 18:00:00",
            "end": null,
            "description": "<p>It's another meeting afterall</p>",
            "created_at": "2015-04-20 15:03:30",
            "updated_at": "2015-05-03 08:46:19",
            "type": {
                "id": "1",
                "name": "General",
                "slug": "general",
                "created_at": "2015-04-18 11:24:00",
                "updated_at": "2015-04-18 11:24:04"
            }
        }
    ]
}

With LengthAwarePaginator -

$paginator = new LengthAwarePaginator($events, count($events), 1);
    return $paginator;

This returns the paginator but the data is the same - meaning the same result set as without the paginator, when I'd expect only one record to be returned per page:

    [{
    "total": 3,
    "per_page": 1,
    "current_page": 1,
    "last_page": 3,
    "next_page_url": "/?page=2",
    "prev_page_url": null,
    "from": 1,
    "to": 3,
    "data": {
        "data" : ".. same as above"
    }
}]

Answer 1

With aggregates you need to implement your own custom paginator, as stated by docs :

Note: Currently, pagination operations that use a groupBy statement cannot be executed efficiently by Laravel. If you need to use a groupBy with a paginated result set, it is recommended that you query the database and create a paginator manually.

See this posts to manually implement pagination:

Laravel 5 - Manual pagination

Manually Creating a Paginator (Laravel 5)

Answer 2

Many people have pointed me to a widely mentioned paragraph in the Laravel documentation,

Note: Currently, pagination operations that use a groupBy statement cannot be executed efficiently by Laravel. If you need to use a groupBy with a paginated result set, it is recommended that you query the database and create a paginator manually.

Not terribly helpful, since I cannot find any example in the documentation as to exactly how to create a manual paginator using the results of an Eloquent query. So, here is what I was able to come up with. Note that you must use ->take() and ->offset() in the query, otherwise you will end up with the same results on every page (this is where I was getting stuck).

<?php
// routes.php
use Illuminate\Pagination\LengthAwarePaginator as Paginator;
    get('test', function(Request $request) {
        $page = $request->has('page') ? $request->input('page') : 1; // Use ?page=x if given, otherwise start at 1
        $numPerPage = 2; // Number of results per page
        $eventType = EventType::find(1); // Not relevant to pagination
        $count = $eventType->memberEvents()->count(); // Get the total number of entries you'll be paging through
        // Get the actual items
        $events = $eventType->memberEvents()->orderBy('start', 'asc')
            ->take($numPerPage)->offset(($page-1)*$numPerPage)->get()->groupBy(function($date) {
            return $date->start->format('F, Y');
        });
        // Create the paginator with Illuminate\Pagination\LengthAwarePaginator as Paginator
        // Pass in the variables supplied above, including the path for pagination links
        $paginator = new Paginator($events, $count, $numPerPage, $page, ['path' => $request->url(), 'query' => $request->query()]);
        return $paginator;
    });

Answer 3

As stated in the Laravel docs...Note: Currently, pagination operations that use a groupBy statement cannot be executed efficiently by Laravel. If you need to use a groupBy with a paginated result set, it is recommended that you query the database and create a paginator manually. Docs

Answer 4

If you want to add groupBy to your data the you should use LengthAwarePaginator object as updated in laravel 5

Try this,

use Illuminate\Pagination\LengthAwarePaginator as Paginator;

$page       = ($request->input('page') != null) ? $request->input('page') : 1;
$perPage    = 1;

$sliced     = array_slice($data, 0, 5); //you can these values as per your requirement 

$paginator  = new Paginator($sliced, count($data), $perPage, $page,['path'  => url()->current(),'query' => $request->query()]);

return $paginator;

$data is your data object and fifth parameters are for next and prev urls

Refer this for more information about paginator, https://laravel.com/api/5.5/Illuminate/Database/Eloquent/Builder.html#method_paginate