javascript - 为什么承诺的“成功”会给我一个函数不存在的错误？

Question

我有一些看起来像这样的代码：

var db = require("../db.js");

module.exports = {
    init: function(app) {
        // run searchin our database
        app.post("/api/search", function (req, res) {
            // generate search sql
            try {
                var sql_tables = "select attraction.id, title, src from attraction LEFT JOIN attraction_picture ON attraction_picture.attraction_id = attraction.id";
                var sql_group_by = " group by attraction.id";
                var sql_order_by = " ORDER BY ";
                var params = {};

                // order those with pictures first, ALWAYS
                sql_order_by += " if (attraction_picture.id IS NOT NULL, 0, 1), 0";

                // order based on those with higher ratings first
                sql_order_by += " + attraction.stars ";

                // give slight preference to those with more ratings (popularity)
                sql_order_by += " + if (reviews > 5000, 5, reviews/1000) ";

                // apply preferences for each different category independently
                if (typeof(req.body.sess_user.filters) != "undefined") {
                    for (var i in req.body.sess_user.filters) {
                        i = parseInt(i); // make sure its an integer
                        if (!req.body.sess_user.filters[i]) continue;

                        // join to figure out if this attraction matches this filter
                        var thistable = "filter_" + i;
                        sql_tables += " LEFT JOIN attraction_filter " + thistable + " ON " + thistable + 
                            ".attraction_id = attraction.id AND " + thistable + ".filter_id=:filter_id_" + i + " ";
                        params["filter_id_" + i] = i;

                        // if it does match, give points or take away points based on the star. 
                        var adjustment_if_matches = (req.body.sess_user.filters[i]) - 3 * 3; 
                        sql_order_by += " + if(" + thistable + ".attraction_id IS NOT NULL, :filter_adjustment_" + i + ", 0) ";
                        params["filter_adjustment_" + i] = adjustment_if_matches;
                    }
                }

                // per page
                sql_order_by += " DESC LIMIT :start, :per_page";
                params.start = 0;
                if (typeof(req.body.start) != "undefined") {
                    params.start = req.body.start; 
                }
                console.log(req.body.start);
                params.per_page = 24; 

                // execute sql and return results
                app.db.q(sql_tables + sql_group_by + sql_order_by, params).success(function(results) {
                    res.json(results);
                });
            } catch (err) {
                console.log("error running search: ");
                console.log(err);
                res.json([]); // @TODO - better error handling
            }
        });

这段代码的作用并不是很重要，但本质上它会通过一个 mysql 数据库并选择其中的某些元素。

在这一行：

// execute sql and return results
                app.db.q(sql_tables + sql_group_by + sql_order_by, params).success(function(results) {
                    res.json(results);

我收到此错误：

$ sudo nodemon app.js 
[nodemon] 1.19.1
[nodemon] to restart at any time, enter `rs`
[nodemon] watching: *.*
[nodemon] starting `node app.js`
Listening on port 80
0
passing raw query replacements as the 4th argument to sequelize.query is deprecated. Please use options.replacements instead
error running search: 
TypeError: app.db.q(...).success is not a function
    at /home/tex/studygit/Planning-App/api/attractions.js:54:68
    at Layer.handle [as handle_request] (/home/tex/studygit/Planning-App/node_modules/express/lib/router/layer.js:76:5)
    at next (/home/tex/studygit/Planning-App/node_modules/express/lib/router/route.js:100:13)
    at Route.dispatch (/home/tex/studygit/Planning-App/node_modules/express/lib/router/route.js:81:3)
    at Layer.handle [as handle_request] (/home/tex/studygit/Planning-App/node_modules/express/lib/router/layer.js:76:5)
    at /home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:227:24
    at Function.proto.process_params (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:305:12)
    at /home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:221:12
    at Function.match_layer (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:288:3)
    at next (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:182:10)
    at /home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:184:16
    at Function.match_layer (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:288:3)
    at next (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:182:10)
    at /home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:184:16
    at Function.match_layer (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:288:3)
    at next (/home/tex/studygit/Planning-App/node_modules/express/lib/router/index.js:182:10)

我很困惑为什么会发生这个错误。此特定功能在我的db.js文件中定义，该文件位于该文件的父目录中。所以它看起来像这样：

- root
    - directory
         . attractions.js
    . db.js

我收到错误的文件是景点.js。正如我所说，该函数的定义位于 db.js 中，如下所示：

// bootstrap the db wrapper
var Sequelize = require('sequelize');
var conf = require("./conf");

// Database Wrapper Initialization
try {
    if (conf.db.type == "mysql") {
        // connect to database 
        var db = new Sequelize("mysql://" + conf.db.username + ":"+conf.db.password+
            "@" + conf.db.host + ":" + conf.db.port + "/" + conf.db.database);
    } else {
        console.log("PROBLEM - UNKNOWN DB TYPE: " + conf.db.type);
        process.exit(1);
    }
} catch (err) {
    console.log("PROBLEM - connecting to db: ");
    console.log(err);
    process.exit(1);
}

// simplified database querying function
db.q = function(query, replace) {
    return this.query(query, null, {raw: true}, replace);
};

module.exports = db; // return our db connection

我只是在制作 Sequelize 模块中提供的简化查询功能。sequelize 模块状态：

public query(sql: string, options: Object): Promise 在数据库上执行查询，有可能绕过所有的 sequelize goodness。

默认情况下，该函数将返回两个参数：一个结果数组和一个元数据对象，包含受影响的行数等。

如果您正在运行不需要元数据的查询类型，例如 SELECT 查询，则可以传入查询类型以对结果进行 sequelize 格式：

sequelize.query('SELECT...').then(([results, metadata]) => {
  // Raw query - use then plus array spread
});

sequelize.query('SELECT...', { type: sequelize.QueryTypes.SELECT }).then(results => {
  // SELECT query - use then
})

如果查询是一个承诺，那为什么我不能使用db.q(...).success？为什么说该功能不存在？我在这里做错了什么我没有看到吗？我对 Javascript 有点陌生，所以很可能......

任何帮助，将不胜感激。谢谢你。

标签： javascriptmysqlnode.jssequelize.js