分页问题

Question

我需要有关使用车把在 Node.js 中分页 table 的代码的帮助。

这是路线的代码：

router.get('/profile', isLoggedIn, async (req, res) => {
    // Get current page from url (request parameter)
    const page_id = parseInt(req.params.page);
    const currentPage = page_id > 0 ? page_id : currentPage;
    //Change pageUri to your page url without the 'page' query string 
    pageUri = '/items/';


    /*Get total items*/
    await pool.query('SELECT COUNT(id) as totalCount FROM user where user_type="Client"', async (err, result,) => {

        // Display 10 items per page
        const perPage = 10,
            totalCount = result[0].totalCount;

        // Instantiate Pagination class
        const Paginate = new Pagination(totalCount, currentPage, pageUri, perPage);


        /*Query items*/
        await db.query('SELECT * FROM user LIMIT ' + Paginate.perPage + ' OFFSET ' + Paginate.start, async (err, result) => {

            data = {
                items: result,
                pages: Paginate.links()
            }

            /* const users = await pool.query('SELECT * FROM database_links.user where user_type="Client"').then;*/
            res.render('profile', { data });
        });
    });
});

这是Pagination.js:

class Pagination{

    constructor(totalCount,currentPage,pageUri,perPage=2){
        this.perPage = perPage;
        this.totalCount =parseInt(totalCount);
        this.currentPage = parseInt(currentPage);
        this.previousPage = this.currentPage - 1;
        this.nextPage = this.currentPage + 1;
        this.pageCount = Math.ceil(this.totalCount / this.perPage);
        this.pageUri = pageUri;
        this.offset  = this.currentPage > 1 ? this.previousPage * this.perPage : 0;
        this.sidePages = 4;
        this.pages = false;
    }
    
    
    
    links(){
        this.pages='<ul class="pagination pagination-md">';
    
        if(this.previousPage > 0)
            this.pages+='<li class="page-item"><a class="page-link" href="'+this.pageUri + this.previousPage+'">Previous</a></li>';
    
    
            /*Add back links*/
            if(this.currentPage > 1){
                for (var x = this.currentPage - this.sidePages; x < this.currentPage; x++) {
                    if(x > 0)
                        this.pages+='<li class="page-item"><a class="page-link" href="'+this.pageUri+x+'">'+x+'</a></li>';
                }
            }
    
            /*Show current page*/
            this.pages+='<li class="page-item active"><a class="page-link" href="'+this.pageUri+this.currentPage+'">'+this.currentPage+'</a></li>';
    
            /*Add more links*/
            for(x = this.nextPage; x <= this.pageCount; x++){
    
                this.pages+='<li class="page-item"><a class="page-link" href="'+this.pageUri+x+'">'+x+' </a></li>';
    
                if(x >= this.currentPage + this.sidePages)
                    break;
            }
    
    
            /*Display next buttton navigation*/
            if(this.currentPage + 1 <= this.pageCount)
                this.pages+='<li class="page-item"><a class="page-link" href="'+this.pageUri+this.nextPage+'">Next</a></li>';
    
            this.pages+='</ul>';
    
        return this.pages;
    }

    

    }
    module.exports = Pagination;

这是html:

<div id="flush-collapseOne" class="accordion-collapse collapse" aria-labelledby="flush-headingOne"
                        data-bs-parent="#accordionFlushExample">
                        <div class="accordion-body">
                            <table class="table table-dark table-borderless">
                                <thead>
                                    <tr class="text-center">
                                        <th scope="col">User_ID</th>
                                        <th scope="col">User_Name</th>
                                        <th scope="col">Full Name</th>
                                        <th scope="col">User type</th>
                                        <th scope="col"></th>
                                    </tr>
                                </thead>
                                <tbody>
                                    {{#each users}}
                                    <tr class="table-dark text-center">
                                        <th scope="row">{{id}}</th>
                                        <td>{{username}}</td>
                                        <td>{{fullname}}</td>
                                        <td>{{user_type}}</td>
                                        <td class="text-center">
                                            <a href="" class="btn btn-danger btn-sm">Eliminar</a>
                                            <a href="" class="btn btn-secondary btn-sm">Editar</a>
                                        </td>
                                    </tr>
                                </tbody>
                                {{else}}
                                <div class="col-md-4 mx-auto">
                                    <div class="card card-body text-center">
                                        <p>There are not users saved yet</p>
                                        <a href="/clients/add">Create One!</a>
                                    </div>
                                </div>
                                {{/each}}
                                {{ pages }}
                            </table>
                        </div>
                    </div>

这是我从控制台得到的错误：

GET /profile - - ms - -
(node:26172) UnhandledPromiseRejectionWarning: ReferenceError: Cannot access 'currentPage' before initialization
    at C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\src\routes\authentications.js:41:49
    at Layer.handle [as handle_request] (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\route.js:137:13)
    at isLoggedIn (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\src\lib\auth.js:5:20)
    at Layer.handle [as handle_request] (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\layer.js:95:5)
    at next (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\route.js:137:13)
    at Route.dispatch (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\route.js:112:3)
    at Layer.handle [as handle_request] (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\layer.js:95:5)
    at C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\index.js:281:22
    at Function.process_params (C:\Users\hacka\Desktop\Web\Proyect_NodeJs_Mysql\node_modules\express\lib\router\index.js:335:12)
(node:26172) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). To terminate the node process on unhandled promise rejection, use the CLI flag `--unhandled-rejections=strict` (see https://nodejs.org/api/cli.html#cli_unhandled_rejections_mode). (rejection id: 4)

Answer 1

您的错误显示 Cannot access 'currentPage' before initialization。

那是因为您试图在 currentPage 定义之前将其分配回 currentPage。而不是：

const currentPage = page_id > 0 ? page_id : currentPage;

将你的初始值放入你的三元语句中：

const currentPage = page_id > 0 ? page_id : 0;

...或：

let currentPage = 0;
if (page_id > 0) currentPage = page_id;

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