node.js - 如果包含在 sequelize 中找不到任何关系数据，则设置属性的空值

Question

我试图找出一本书可以有多个横幅的书。
所以我在找书的时候应用了很多横幅的关系。
它工作正常，但如果书籍没有任何横幅，我希望响应有所不同。

Book.findAll({
                order: [
                    ['updated_at', 'ASC']
                ],
                attributes: {
                    exclude: ["thumbnail", "listenTime", "created_at", "today_book_day"],
                },
                include: [{
                        model: banner,
                        as: 'banners',
                        attributes: [
                            [banner_attribute, 'url']
                        ],
                        where: whereAttribute,
                        required: false
                    }
                ]
            }).then(books => {
                var totalPage = 1;
                if (totalBooks){
                    totalPage = Math.ceil(totalBooks / pagesize);
                }
                var metaInfo = {
                    currentPage: parseInt(page),
                    totalPage: totalPage,
                    pagesize: pagesize
                };
                var output = {
                    'meta': metaInfo,
                    "data": books,
                    "status": 200
                };
                res.send(output);
            });

得到如下响应:

{
    "meta": {
        "currentPage": 1,
        "totalPage": 3,
        "pagesize": 100
    },
    "data": [
        {
            "id": 114,
            "rating": "5.00",
            "like": -1,
            "comment": 0,
            "listen": 49,
            "category": "[]",
            "order": 9,
            "updated_at": 1589475237,
            "thumbnailUrl": null,
            "banners": []
        },
        "status": 200
    ]
}

但我想要像下面这样的 JSON 响应:

{
    "meta": {
        "currentPage": 1,
        "totalPage": 3,
        "pagesize": 100
    },
    "data": [
        {
            "id": 114,
            "rating": "5.00",
            "like": -1,
            "comment": 0,
            "listen": 49,
            "category": "[]",
            "order": 9,
            "updated_at": 1589475237,
            "thumbnailUrl": null,
            "banners": [
                {
                    "url" : null
                }
            ],
        },
        "status": 200
    ]
}

Answer 1

这是无效的 JSON

"banners": [url" : null] // table of... what?

我想你想要这样的东西？

"banners": [ {"url" : null} ] // table with one object, which has key 'url' and value 'null'

但是如果横幅数组为空，那么您可以得出 url 为空的结论。您不需要明确地放置这些信息。