How to implement pagination functionality outside of Laravel

First of all, Laravel is a very popular PHP framework that provides a series of functions and tools to help us quickly develop web applications. One of the very useful functions is paging. Laravel provides a built-in paging class Paginator, which can easily perform data paging operations. However, sometimes we may need to use paging in an environment outside of Laravel, such as in a PHP program written by ourselves, in which case we need to implement the paging function ourselves.

In this article, we will introduce how to implement the paging function in an environment outside of Laravel, and solve some error reporting problems you may encounter.

1. Implementation of paging function

First, let us take a look at the specific implementation method of paging. In the data we want to paginate, we need to clarify the following parameters:

1. Total data volume: total

2. Amount of data displayed per page: perPage

3. Current page number: currentPage

Through these parameters, we can achieve paging of data. The following is a sample code:

<?php

$total = 1000; //总数据量
$perPage = 20; //每页显示的数据量
$currentPage = 1; //当前页数

//计算总页数
$totalPages = ceil($total / $perPage);

//计算当前页要显示的数据
$data = array();
for($i = ($currentPage - 1) * $perPage; $i < $currentPage * $perPage; $i++){
    if($i < $total){
        $data[] = $i;
    }else{
        break;
    }
}

//输出分页数据
echo json_encode(array(
    &#39;total&#39; => $total,
    'perPage' => $perPage,
    'currentPage' => $currentPage,
    'totalPages' => $totalPages,
    'data' => $data
));

Here we use PHP's native calculation method to implement data paging. First, we calculate the total number of pages through the total amount of data and the amount of data displayed on each page, and then use the current page number to calculate the data to be displayed on the current page. Finally, the paging data is output and displayed in json format.

2. Possible error reports

In the process of using the paging function, you may encounter some error reports. Let's take a look at the errors you may encounter and their solutions.

1. Undefined variable: items

When using Laravel's built-in Paginator paging function, if this error occurs, it is usually because the paging data is not set correctly. Specifically, we may forget to call the paginate method to get the data, or not pass the data to the Paginator class correctly.

Solution: Make sure to call the paginate method correctly, as follows:

$items = DB::table('users')->paginate(15);

2. Call to undefined method Illuminate\Pagination\LengthAwarePaginator::links()

In When using Laravel's built-in Paginator paging function, if this error occurs, it is usually because we did not pass the parameters correctly when using the links() method. Specifically, we need to pass the LengthAwarePaginator class object as a parameter to the links() method.

Solution: Make sure to pass the parameters correctly as follows:

$items = DB::table('users')->paginate(15);
echo $items->links('vendor.pagination.bootstrap-4');

3. Method Illuminate\Database\Query\Builder::paginate does not exist.

In When using Laravel's built-in Paginator pagination function, if this error occurs, it is usually because we did not call the paginate() method correctly when using it. Specifically, we may have forgotten to pass the query results to the paginate() method.

Solution: Make sure the query results are correctly passed to the paginate() method, as shown below:

$items = DB::table('users')->where('active', true)->paginate(15);

Summary

In this article, we introduced how to Implement the paging function in external environments and solve some error reporting problems that may be encountered. The paging function is one of the most commonly used functions in web development. It can help us better manage and display data. Whether in Laravel or in other frameworks or contexts, we need to master the implementation of paging and avoid the errors encountered.

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