Question

我使用了nested query格式，当我在 second console.log(main_array)部分中打印db.query时工作正常，这将在单个数组中返回parent_category和child类别，例如父子关系，但是当我发送全部数据outside of second query部分时，它将仅返回parent category而不是全部数据。

我在 nodeJs 中使用了以下脚本。

learnAPI: (req, res) => {
    let query = "SELECT * FROM category where parent_id IS NULL";
    const main_array = {};
    var tets = {};
    db.query(query, (err, result) => {
        if (err) {
        return res.status(500).send(err);
        }
        Object.keys(result).forEach(function (key) {
            let cat_name = result[key]['name'];
            main_array[cat_name] = result[key];
            let getsubcategory = "SELECT * FROM category where parent_id = " + result[key]['id'];
            db.query(getsubcategory, (err, subcategory) => {
                Object.keys(subcategory).forEach(function (key) {
                    let sub_name = subcategory[key]['name'];
                    main_array[cat_name][sub_name] = subcategory[key];
                });
                tets = main_array;
            });
            console.log(tets);
        });
        res.setHeader('Content-Type', "application/json");
        res.status(200).send(main_array);
    });
},

任何人都知道我该怎么做到吗？

Answer 1

尝试一下：

 learnAPI: (req, res) => {
    let query = "SELECT * FROM category where parent_id IS NULL";
    let main_array = {};
    let tets = [];
    db.query(query, (err, result) => {
        if (err) {
        return res.status(500).send(err);
        }
        Object.keys(result).forEach(function (key) {
            let cat_name = result[key]['name'];
            main_array[cat_name] = result[key];
            let getsubcategory = "SELECT * FROM category where parent_id = " + result[key]['id'];
            db.query(getsubcategory, (err, subcategory) => {
                Object.keys(subcategory).forEach(function (key) {
                    let sub_name = subcategory[key]['name'];
                    main_array[cat_name][sub_name] = subcategory[key];
                });
                tets.push(main_array);
            });
            console.log(tets);
        });
        res.setHeader('Content-Type', "application/json");
        res.status(200).send(main_array);
    });
}

无法在nodeJs中的嵌套查询块之外获取结果

1 个答案: