无法从模块导出中获取变量

Question

我有一个connector.js文件，我想用它来导出dbResult对象。

(function(){
var Massive = require("massive");
var connectionString = "postgres://postgres:postgres@localhost/postgres";
var db = Massive.connectSync({connectionString : connectionString});
var dbResult ;
 db.query("Select * from company", function (err, data) {
        dbResult = data;
        console.log(data);
    });
})(module.exports);

现在在另一个文件中，我试图获得dbResult并显示数据:

var express = require("express");
var app = express();
var connectorObject = require("./Connector.js");
var Massive = require("massive");
app.get("/api/Steves",function(req,res){
        res.set("Content-Type","application/json");
        res.send(connectorObject.dbResult);
    });

app.listen(3000);
console.log("Server Started on port 3000...");

但是当我启动URL时，没有看到任何响应。

Answer 1

您要做的是返回一个函数，可以稍后对结果求值:

var Massive = require("massive");
var connectionString = "postgres://postgres:postgres@localhost/postgres";
var db = Massive.connectSync({connectionString : connectionString});
module.exports.getCompanies = function(callback) {
    db.query("Select * from company", callback);
}

然后你可以从你的其他文件中访问它:

var connector = require('./Connector');
connector.getCompanies(function( err, data ) {
    if ( err ) return console.error( err );
    console.log( data );
});