Node.js：使用回调或异步的值调用函数 [英] Node.js : Call function using value from callback or async

问题描述

我写了下面的.js文件来调用下面定义的函数。
objectRepositoryLoader.readObjectRepository（）返回一个hashmap从哪里必须使用 enterUserName（），enterPassword（），clickLoginButton ）函数。

  var path = require（'path'）; 
 var elementRepoMap = {} 
 
 var LandingPage = function（）{
 var fileName = path.basename（module.filename，path.extname（module.filename））
 
 objectRepositoryLoader.readObjectRepository（fileName +'。xml'，function（elementRepo）{
 console.log（elementRepo）//这里打印的值
 this.elementRepoMap = elementRepo 
}）; 
 
 this.enterUserName = function（value）{
 console.log（elementRepoMap）//这里不打印值
 //有些代码
}; 
 
 this.enterPassword = function（value）{
 //有些代码
}; 
 
 this.clickLoginButton = function（）{
 //有些代码
}; 
}; 
 module.exports = new LandingPage（）; 
  

objectRepositoryLoader.readObjectRepository（）在另一个文件如下：

  var ObjectRepositoryLoader = function（）{
 
 this.readObjectRepository = function（fileName，callback）{
 var filePath ='./elementRepository/'+fileName; 
 this.loadedMap = this.objectRepoLoader（filePath，function（loadedMap）{
 return callback（loadedMap）; 
}）; 
} 
 
 this.objectRepoLoader = function（filePath，callback）{
 if（filePath.includes（。xml））{
 this.xmlObjectRepositoryLoader ，function（loadedMap）{
 return callback（loadedMap）; 
}）; 
} 
 
 this.xmlObjectRepositoryLoader = function（xmlPath，callback）{
 var innerMap = {}; 
 var elementName; 
 fs.readFile（xmlPath，utf-8，function（err，data）{
 if（err）{
 console.log（'File not found !!'）
} 
 else {
 var doc = domparser.parseFromString（data，text / xml）; 
 var elements = doc.getElementsByTagName（A1）; 
 （var i = 0; i  var elm = elements [i]; 
 elementName = elm.getAttribute（name）; 
 var params = elm .getElementsByTagName（AS）; 
 innerMap = {}; 
 for（var j = 0; j< params.length; j ++）{
 var param = params [j]; 
 var locatorType = param.getAttribute（type）; 
 var locatorValue = param.getAttribute（value）; 
 innerMap [locatorType] = locatorValue; 
} 
 loadedMap [elementName] = innerMap; 
 innerMap = {}; 
}; 
} 
 return callback（loadedMap）; 
}）; 
};我如何调用 enterUserName（），enterPassword（），clickLoginButton（），如下图所示：
 



< 函数从spec.js文件，并有任何方式，我可以避免使用回调并使用 async.js 并从spec.js文件调用 enterUserName（），enterPassword（），clickLoginButton（）？

EDIT
我已如下修改我的文件：

  this.xmlObjectRepositoryLoader = function （xmlPath）{
 var innerMap = {}; 
 var elementName; 
 var filePath = xmlPath +'。xml'
 var self = this 
 return new Promise（
 function（resolve，reject）{
 console.log（In xmlObjectRepositoryLoader ：+ filePath）
 self.readFilePromisified（filePath）
 .then（text => {
 var doc = domparser.parseFromString（text，text / xml）; 
 var elements = doc.getElementsByTagName（Element）; 
 for（var i = 0; i  var elm = elements [i]; 
 elementName = elm.getAttribute（name）; 
 var params = elm.getElementsByTagName（param）; 
 innerMap = {}; 
 for（var j = 0; j < length; j ++）{
 var param = params [j]; 
 var locatorType = param.getAttribute（type）; 
 var locatorValue = param.getAttribute（value）; 
 innerMap [locatorType] = locatorValue; 
} 
 map [elementName] = innerMap; 
 innerMap = {}; 
} 
 console.log（map）//打印地图
 resolve（text）
}）
 .catch（error => {
 reject（error）
}）; 
}）; 
} 
 
 this.readFilePromisified = function（filename）{
 console.log（In readFilePromisified：+ filename）
 return new Promise function（resolve，reject）{
 fs.readFile（filename，{encoding：'utf8'}，
（error，data）=> {
 if（error）{
拒绝（错误）; 
} else {
 resolve（data）; 
} 
}）
}）
} 
  

我从另一个文件调用上述函数，如下所示：

  objectRepositoryLoader.readObjectRepository（fileName）
 .then（text => {
 console.log（text）; 
}）
 .catch error => {
 console.log（error）; 
}）; 
  

但它给我的错误是

  .then（text => {^ 
 
 TypeError：无法读取未定义的属性'then'
  
解决方案
您可以使用async.waterfall和 async.parallel 可执行此任务
 
 
 
请参阅参考 
 
 
 
我刚刚尝试过您的代码使其工作，我在评论中解释了实现方式。
  async.waterfall（[
 function（next）{
 objectRepositoryLoader.readObjectRepository（fileName +'。xml'，next） // pass this next as this function defination and after manipulation return result with callback like this（null，result）
 
} 
]，function（err，result）{
 
 if（！err）{
 // Do wahtever你想要的结果
 
 async.parallel（[
 function（callback）{
 this .enterUserName = function（value）{
 console.log（elementRepoMap）
 //有些代码
}; 
}，
 function（callback）{
 this.enterPassword = function（value）{
 // Some Code 
}; 
}，
 function（callback）{
 
 this.clickLoginButton = function（）{
 // Some Code 
}; 
} 
]，function（err，results）{
 //可选回调
}; 
} 
}）
  
 
I have written below .js file to call below defined function.
objectRepositoryLoader.readObjectRepository() returns me a hashmap from where i have to use values in enterUserName(), enterPassword(), clickLoginButton() functions.
var path = require('path');
var elementRepoMap = {}

var LandingPage = function(){
    var fileName = path.basename(module.filename, path.extname(module.filename))

    objectRepositoryLoader.readObjectRepository(fileName+'.xml' , function(elementRepo){
        console.log(elementRepo) //values are being printed here
        this.elementRepoMap = elementRepo
    }); 

    this.enterUserName = function(value){
        console.log(elementRepoMap) //values are not being printed here
        //Some Code     
    };

    this.enterPassword = function(value){
        //Some Code
    };

    this.clickLoginButton = function(){
        //Some Code
    };  
};
module.exports = new LandingPage();
The objectRepositoryLoader.readObjectRepository() function defined in another file is as below:
var ObjectRepositoryLoader = function() {

    this.readObjectRepository = function(fileName, callback) {        
        var filePath = './elementRepository/'+fileName;
        this.loadedMap = this.objectRepoLoader(filePath, function(loadedMap){
            return callback(loadedMap);
        });
    }

    this.objectRepoLoader = function(filePath, callback){
        if (filePath.includes(".xml")) {
            this.xmlObjectRepositoryLoader(filePath, function(loadedMap){
                return callback(loadedMap);                
        });
    }

    this.xmlObjectRepositoryLoader = function (xmlPath, callback){
        var innerMap = {};
        var elementName;
        fs.readFile(xmlPath, "utf-8",function(err, data) {
            if(err){
                console.log('File not found!!')
            }
            else{
                var doc = domparser.parseFromString(data,"text/xml");
                var elements = doc.getElementsByTagName("A1");
                for(var i =0 ; i< elements.length;i++){
                    var elm = elements[i];
                    elementName = elm.getAttribute("name");
                    var params = elm.getElementsByTagName("AS");
                    innerMap = {};
                    for(var j =0 ; j< params.length;j++){
                        var param = params[j];
                        var locatorType = param.getAttribute("type");
                        var locatorValue = param.getAttribute("value");
                        innerMap[locatorType] = locatorValue;
                    }
                    loadedMap[elementName] = innerMap;
                    innerMap={};
                };
            }
            return callback(loadedMap);         
        });        
    };
How can I call enterUserName(), enterPassword(), clickLoginButton() function from spec.js file and is there any way I can avoid using callback and use async.js and call enterUserName(), enterPassword(), clickLoginButton() from spec.js file ?

EDIT
I have modified my file like below:
this.xmlObjectRepositoryLoader = function (xmlPath){
        var innerMap = {};
        var elementName;
        var filePath = xmlPath+'.xml'
        var self = this
        return new Promise(
            function(resolve, reject){
                console.log("In xmlObjectRepositoryLoader : "+filePath)
                self.readFilePromisified(filePath)
                .then(text => {
                    var doc = domparser.parseFromString(text,"text/xml");
                    var elements = doc.getElementsByTagName("Element");
                    for(var i =0 ; i< elements.length;i++){
                        var elm = elements[i];
                        elementName = elm.getAttribute("name");
                        var params = elm.getElementsByTagName("param");
                        innerMap = {};
                        for(var j =0 ; j< params.length;j++){
                            var param = params[j];
                            var locatorType = param.getAttribute("type");
                            var locatorValue = param.getAttribute("value");
                            innerMap[locatorType] = locatorValue;
                        }
                        map[elementName] = innerMap;
                        innerMap={};
                    }
                    console.log(map) // prints the map
                    resolve(text)
                })
                .catch(error => {
                    reject(error)
                });
            });
        }

this.readFilePromisified = function(filename) {
        console.log("In readFilePromisified : "+filename)
        return new Promise(
            function (resolve, reject) {
                fs.readFile(filename, { encoding: 'utf8' },
                (error, data) => {
                    if (error) {
                        reject(error);
                    } else {
                        resolve(data);
                    }
                })
            })
        }
I am calling above function from another file as below:
objectRepositoryLoader.readObjectRepository(fileName)
    .then(text => {
        console.log(text);
    })
    .catch(error => {
        console.log(error);
    });
But it gives me error as
     .then(text => {   ^

TypeError: Cannot read property 'then' of undefined
In this case how can I use promise to call another promise function and then use the returned value in one more promise function and return calculated value to calling function where I can use the value in other functions. I sound a bit confused. Please help
解决方案
You can use async.waterfall and async.parallel to perform this task

see the reference 

I just tried your code to make it working, I explained the way of implementation in comment. 
async.waterfall([
function(next){
    objectRepositoryLoader.readObjectRepository(fileName+'.xml' ,next)//pass this next as parameter in this function defination and after manipulation return result with callback like this(null,result)

}
  ],function(err,result){

    if(!err){
      //Do wahtever you want with result

async.parallel([
    function(callback){
          this.enterUserName = function(value){
        console.log(elementRepoMap)
        //Some Code     
    };
     },
    function(callback){ 
          this.enterPassword = function(value){
        //Some Code
    };
    },
        function(callback){ 

    this.clickLoginButton = function(){
        //Some Code
    };
        }
], function(err, results) {
    // optional callback
};
    }
  })


                        
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