admin/vendor/maatwebsite/excel/config/excel.php

<?php

use Maatwebsite\Excel\Excel;

return [
    'exports' => [

        /*
        |--------------------------------------------------------------------------
        | Chunk size
        |--------------------------------------------------------------------------
        |
        | When using FromQuery, the query is automatically chunked.
        | Here you can specify how big the chunk should be.
        |
        */
        'chunk_size'             => 1000,

        /*
        |--------------------------------------------------------------------------
        | Pre-calculate formulas during export
        |--------------------------------------------------------------------------
        */
        'pre_calculate_formulas' => false,

        /*
        |--------------------------------------------------------------------------
        | Enable strict null comparison
        |--------------------------------------------------------------------------
        |
        | When enabling strict null comparison empty cells ('') will
        | be added to the sheet.
        */
        'strict_null_comparison' => false,

        /*
        |--------------------------------------------------------------------------
        | CSV Settings
        |--------------------------------------------------------------------------
        |
        | Configure e.g. delimiter, enclosure and line ending for CSV exports.
        |
        */
        'csv'                    => [
            'delimiter'              => ',',
            'enclosure'              => '"',
            'line_ending'            => PHP_EOL,
            'use_bom'                => false,
            'include_separator_line' => false,
            'excel_compatibility'    => false,
            'output_encoding'        => '',
            'test_auto_detect'       => true,
        ],

        /*
        |--------------------------------------------------------------------------
        | Worksheet properties
        |--------------------------------------------------------------------------
        |
        | Configure e.g. default title, creator, subject,...
        |
        */
        'properties'             => [
            'creator'        => '',
            'lastModifiedBy' => '',
            'title'          => '',
            'description'    => '',
            'subject'        => '',
            'keywords'       => '',
            'category'       => '',
            'manager'        => '',
            'company'        => '',
        ],
    ],

    'imports'            => [

        /*
        |--------------------------------------------------------------------------
        | Read Only
        |--------------------------------------------------------------------------
        |
        | When dealing with imports, you might only be interested in the
        | data that the sheet exists. By default we ignore all styles,
        | however if you want to do some logic based on style data
        | you can enable it by setting read_only to false.
        |
        */
        'read_only'    => true,

        /*
        |--------------------------------------------------------------------------
        | Ignore Empty
        |--------------------------------------------------------------------------
        |
        | When dealing with imports, you might be interested in ignoring
        | rows that have null values or empty strings. By default rows
        | containing empty strings or empty values are not ignored but can be
        | ignored by enabling the setting ignore_empty to true.
        |
        */
        'ignore_empty' => false,

        /*
        |--------------------------------------------------------------------------
        | Heading Row Formatter
        |--------------------------------------------------------------------------
        |
        | Configure the heading row formatter.
        | Available options: none|slug|custom
        |
        */
        'heading_row'  => [
            'formatter' => 'slug',
        ],

        /*
        |--------------------------------------------------------------------------
        | CSV Settings
        |--------------------------------------------------------------------------
        |
        | Configure e.g. delimiter, enclosure and line ending for CSV imports.
        |
        */
        'csv'          => [
            'delimiter'        => null,
            'enclosure'        => '"',
            'escape_character' => '\\',
            'contiguous'       => false,
            'input_encoding'   => 'UTF-8',
        ],

        /*
        |--------------------------------------------------------------------------
        | Worksheet properties
        |--------------------------------------------------------------------------
        |
        | Configure e.g. default title, creator, subject,...
        |
        */
        'properties'   => [
            'creator'        => '',
            'lastModifiedBy' => '',
            'title'          => '',
            'description'    => '',
            'subject'        => '',
            'keywords'       => '',
            'category'       => '',
            'manager'        => '',
            'company'        => '',
        ],

        /*
       |--------------------------------------------------------------------------
       | Cell Middleware
       |--------------------------------------------------------------------------
       |
       | Configure middleware that is executed on getting a cell value
       |
       */
        'cells'        => [
            'middleware' => [
                //\Maatwebsite\Excel\Middleware\TrimCellValue::class,
                //\Maatwebsite\Excel\Middleware\ConvertEmptyCellValuesToNull::class,
            ],
        ],

    ],

    /*
    |--------------------------------------------------------------------------
    | Extension detector
    |--------------------------------------------------------------------------
    |
    | Configure here which writer/reader type should be used when the package
    | needs to guess the correct type based on the extension alone.
    |
    */
    'extension_detector' => [
        'xlsx'     => Excel::XLSX,
        'xlsm'     => Excel::XLSX,
        'xltx'     => Excel::XLSX,
        'xltm'     => Excel::XLSX,
        'xls'      => Excel::XLS,
        'xlt'      => Excel::XLS,
        'ods'      => Excel::ODS,
        'ots'      => Excel::ODS,
        'slk'      => Excel::SLK,
        'xml'      => Excel::XML,
        'gnumeric' => Excel::GNUMERIC,
        'htm'      => Excel::HTML,
        'html'     => Excel::HTML,
        'csv'      => Excel::CSV,
        'tsv'      => Excel::TSV,

        /*
        |--------------------------------------------------------------------------
        | PDF Extension
        |--------------------------------------------------------------------------
        |
        | Configure here which Pdf driver should be used by default.
        | Available options: Excel::MPDF | Excel::TCPDF | Excel::DOMPDF
        |
        */
        'pdf'      => Excel::DOMPDF,
    ],

    /*
    |--------------------------------------------------------------------------
    | Value Binder
    |--------------------------------------------------------------------------
    |
    | PhpSpreadsheet offers a way to hook into the process of a value being
    | written to a cell. In there some assumptions are made on how the
    | value should be formatted. If you want to change those defaults,
    | you can implement your own default value binder.
    |
    | Possible value binders:
    |
    | [x] Maatwebsite\Excel\DefaultValueBinder::class
    | [x] PhpOffice\PhpSpreadsheet\Cell\StringValueBinder::class
    | [x] PhpOffice\PhpSpreadsheet\Cell\AdvancedValueBinder::class
    |
    */
    'value_binder'       => [
        'default' => Maatwebsite\Excel\DefaultValueBinder::class,
    ],

    'cache'        => [
        /*
        |--------------------------------------------------------------------------
        | Default cell caching driver
        |--------------------------------------------------------------------------
        |
        | By default PhpSpreadsheet keeps all cell values in memory, however when
        | dealing with large files, this might result into memory issues. If you
        | want to mitigate that, you can configure a cell caching driver here.
        | When using the illuminate driver, it will store each value in the
        | cache store. This can slow down the process, because it needs to
        | store each value. You can use the "batch" store if you want to
        | only persist to the store when the memory limit is reached.
        |
        | Drivers: memory|illuminate|batch
        |
        */
        'driver'      => 'memory',

        /*
        |--------------------------------------------------------------------------
        | Batch memory caching
        |--------------------------------------------------------------------------
        |
        | When dealing with the "batch" caching driver, it will only
        | persist to the store when the memory limit is reached.
        | Here you can tweak the memory limit to your liking.
        |
        */
        'batch'       => [
            'memory_limit' => 60000,
        ],

        /*
        |--------------------------------------------------------------------------
        | Illuminate cache
        |--------------------------------------------------------------------------
        |
        | When using the "illuminate" caching driver, it will automatically use
        | your default cache store. However if you prefer to have the cell
        | cache on a separate store, you can configure the store name here.
        | You can use any store defined in your cache config. When leaving
        | at "null" it will use the default store.
        |
        */
        'illuminate'  => [
            'store' => null,
        ],

        /*
        |--------------------------------------------------------------------------
        | Cache Time-to-live (TTL)
        |--------------------------------------------------------------------------
        |
        | The TTL of items written to cache. If you want to keep the items cached
        | indefinitely, set this to null.  Otherwise, set a number of seconds,
        | a \DateInterval, or a callable.
        |
        | Allowable types: callable|\DateInterval|int|null
        |
         */
        'default_ttl' => 10800,
    ],

    /*
    |--------------------------------------------------------------------------
    | Transaction Handler
    |--------------------------------------------------------------------------
    |
    | By default the import is wrapped in a transaction. This is useful
    | for when an import may fail and you want to retry it. With the
    | transactions, the previous import gets rolled-back.
    |
    | You can disable the transaction handler by setting this to null.
    | Or you can choose a custom made transaction handler here.
    |
    | Supported handlers: null|db
    |
    */
    'transactions' => [
        'handler' => 'db',
        'db'      => [
            'connection' => null,
        ],
    ],

    'temporary_files' => [

        /*
        |--------------------------------------------------------------------------
        | Local Temporary Path
        |--------------------------------------------------------------------------
        |
        | When exporting and importing files, we use a temporary file, before
        | storing reading or downloading. Here you can customize that path.
        | permissions is an array with the permission flags for the directory (dir)
        | and the create file (file).
        |
        */
        'local_path'          => storage_path('framework/cache/laravel-excel'),

        /*
        |--------------------------------------------------------------------------
        | Local Temporary Path Permissions
        |--------------------------------------------------------------------------
        |
        | Permissions is an array with the permission flags for the directory (dir)
        | and the create file (file).
        | If omitted the default permissions of the filesystem will be used.
        |
        */
        'local_permissions'   => [
            // 'dir'  => 0755,
            // 'file' => 0644,
        ],

        /*
        |--------------------------------------------------------------------------
        | Remote Temporary Disk
        |--------------------------------------------------------------------------
        |
        | When dealing with a multi server setup with queues in which you
        | cannot rely on having a shared local temporary path, you might
        | want to store the temporary file on a shared disk. During the
        | queue executing, we'll retrieve the temporary file from that
        | location instead. When left to null, it will always use
        | the local path. This setting only has effect when using
        | in conjunction with queued imports and exports.
        |
        */
        'remote_disk'         => null,
        'remote_prefix'       => null,

        /*
        |--------------------------------------------------------------------------
        | Force Resync
        |--------------------------------------------------------------------------
        |
        | When dealing with a multi server setup as above, it's possible
        | for the clean up that occurs after entire queue has been run to only
        | cleanup the server that the last AfterImportJob runs on. The rest of the server
        | would still have the local temporary file stored on it. In this case your
        | local storage limits can be exceeded and future imports won't be processed.
        | To mitigate this you can set this config value to be true, so that after every
        | queued chunk is processed the local temporary file is deleted on the server that
        | processed it.
        |
        */
        'force_resync_remote' => null,
    ],
];