javascript - 获取分页的下一个偏移量 Sequelize

Question

我想知道分页的正确方法，特别是获取下一页并在响应中让用户知道它。我也不想在响应中透露 count 值。

所以我目前的实现有这样的 react :

{
    "offset": 0,
    "count": 8,
    "nextPageOffset": 100,
    "categories": [
        {
            ......

但是我意识到我的 nextPageOffset 值是错误的，并且可能会产生错误，比如用户可能会跳过一些数据。

const nextPageOffset = offset + limit

我该怎么做？

这是我的 Controller :

// Get all the categories.
exports.getCategories = (req, res) => {
  const offset = parseInt(req.query.offset, 10)
  const limit = parseInt(req.query.limit, 10)

  db.Category.findAndCountAll({ where: {}, offset: offset, limit: limit })
  .then(data => {
    const rows = data.rows
    const count = data.count

    const object = { }

    let nextPageOffset = offset + limit
    //if count >

    object.offset = offset
    object.count = count
    object.nextPageOffset = nextPageOffset
    object.categories = rows

    res.send(object)
  })
  .catch(err => {
    console.log("Error get categories: " + err.message)
    res.status(500).send({
      message: "An error has occured while retrieving data."
    })
  })
}

Answer 1

我的方法是让所有使用分页的路由响应中的所有调用都相同，因为这样我的项目最终看起来像这样

https://github.com/balexandre/so61791627

在你的例子中，我会写:

const listAllProducts = async (req, res) => {
  const page = util.parser.tryParseInt(req.query.page, 0);
  const limit = util.parser.tryParseInt(req.query.limit, 10);

  try {
    const result = await db.products.findAndCountAll({
      where: {
        active: '1',
      },
      offset: limit * page,
      limit: limit,
      order: [["id", "ASC"]],
    });

    res.json(util.response.paging(result, page, limit));
  } catch (err) {
    res.json({ error: err.message });
  }
};

为了保持一致，我会让我的回答看起来像

exports.paging = (sequelizeResult, page, limit) => ({
    page: page,
    limit: limit,
    total: sequelizeResult.count,
    data: sequelizeResult.rows,
})

这样你就不会像当前那样在 data 前面加上 categories 前缀，如果它是例如 users 或 products，“模式”就会改变......

注意 :遇到 result 而不是 data 也很常见

路线会像

GET /products
or
GET /products?limit=2&page=2

输出将是，对于 GET /products?limit=2&page=2

HTTP/1.1 200 OK
X-DNS-Prefetch-Control: off
X-Frame-Options: SAMEORIGIN
Strict-Transport-Security: max-age=15552000; includeSubDomains
X-Download-Options: noopen
X-Content-Type-Options: nosniff
X-XSS-Protection: 1; mode=block
Content-Type: application/json; charset=utf-8
Content-Length: 237
ETag: W/"ed-gK+xNNQgqp7jq/ZbZ3qja3u0680"
Date: Thu, 14 May 2020 09:36:55 GMT
Connection: close

{
  "page": 2,
  "limit": 2,
  "total": 9,
  "data": [
    {
      "id": 5,
      "name": "Product 5",
      "description": "Description for product 5",
      "price": "1.25",
      "active": true
    },
    {
      "id": 6,
      "name": "Product 6",
      "description": "Description for product 6",
      "price": "6.55",
      "active": true
    }
  ]
}