使用 mongoDB 和 express.js 实现分页 REST API答案

【问题标题】：implement pagination REST API using mongoDB and express.js使用 mongoDB 和 express.js 实现分页 REST API
【发布时间】：2021-06-21 15:14:20
【问题描述】：

我有四个收藏mixed, organic, upcycle, vegan 这些都有相同的字段：

// scheme
    const productsSchema = new Schema({
        _id: Schema.Types.ObjectId,
        kind: {
            "upcycle": Boolean,
            "organic": Boolean,
            "vegan": Boolean
        },
        koLCategory: String,
        enLCategory: String,
        sCategory: String,
        koBrandName: String,
        enBrandName: String,
        productName: String,
        thumbNail: String,
        originPrice: String,
        discountPrice: String,
        url: String,
        soldout: Boolean
    });

    const mixedModel = products_conn.model('products', productsSchema, 'mixed');
    const organicModel = products_conn.model('products', productsSchema, 'organic');
    const upcycleModel = products_conn.model('products', productsSchema, 'upcycle');
    const veganModel = products_conn.model('products', productsSchema, 'vegan');

    module.exports = {
        mixedModel,
        organicModel,
        upcycleModel,
        veganModel
    };

我想做的是制作分页 REST API。这段代码只是实现了 REST API（不是分页）

router.route('/category/outer/all').get((req, res) => {
    const upcycle = upcycleModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const organic = organicModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const vegan = veganModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const mixed = mixedModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    Promise.all([
        upcycle,
        organic,
        vegan,
        mixed
    ]).then(data => res.json({
            product: {
                totalCnt: data[0].length + data[1].length + data[2].length + data[3].length,
                items: data[0].concat(data[1]).concat(data[2]).concat(data[3])
            }
        })).catch(err => res.status(400).json('Error: ' + err));
});

在这种情况下，如何生成 REST API 分页？
我知道，将所有数据推送到一个集合中并仅使用 skip, limit 非常简单。
但为了更有效地管理数据，我根据类别值分离集合。
除了将所有数据推送到一个集合中之外，还有其他解决方案吗？

【问题讨论】：

标签： mongodb express pagination

【解决方案1】：

我自己解决了这个问题，代码是：

router.route('/category/outer/all/:page').get((req, res) => {
    const upcycle = upcycleModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const organic = organicModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const vegan = veganModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    const mixed = mixedModel.aggregate([
        {"$match": {"soldout": false, "koLCategory": "keyword"}},
        {"$project":
            {
                "_id": 0,
                "soldout": 0,
            }
        }
    ]);
    /* this part */
    const page = req.params.page;
    const limit = 30;
    const startIndex = (page - 1) * limit;
    const endIndex = page * limit;
    Promise.all([
        upcycle,
        organic,
        vegan,
        mixed
    ]).then(data => {
        result = data[0].concat(data[1]).concat(data[2]).concat(data[3]).slice(startIndex, endIndex);
        res.json({
            product: {
                totalCnt: result.length,
                items: result
            }
        })
    }).catch(err => res.status(400).json('Error: ' + err));
});

如果你有更高效的解决方案，请留下cmets。

【讨论】：