量角器：嘗試返回值時出現undefined

Question

我寫了一個函數，它發送GET請求並返回響應。

this.generateToken = function() { 
    var options = { 
     uri: 'http://localhost:10000/token', 
     method: 'GET', 
     headers: { 
     'Authorization': "YWRtaW46YWRtaW4=" 
     }, 
    }; 
    request(options, function (error, response, body) { 
     var messageresponse = response.body.toString(); 
     console.log(messageresponse); //I am able to print the response 
     return messageresponse; 
    }); 
}; 

我能夠在request（）中打印'messageresponse'變量的值。
此功能正從我的測試的一個叫：

it('Post a GET request and generate a response', function() { 
    var response = commonFunctionObj.generateToken(); 
    response.then(function(value){  //Getting below mentioned error on this line 
     console.log(value); 
    }); 
}); 

四處錯誤：在格蘭調用函數TypeError: Cannot read property 'then' of undefined。
有人可以幫忙嗎？

Answer 1

您需要創建一個承諾並解決它一次以接收響應。 看看下面的代碼。現在

this.generateToken = function() { 
var deffered = protractor.promise.defer(); //create a promise 
var options = { 
    uri: 'http://localhost:10000/token', 
    method: 'GET', 
    headers: { 
    'Authorization': "YWRtaW46YWRtaW4=" 
    }, 
}; 
    request(options, function (error, response, body) { 
    var messageresponse = response.body.toString(); 
    console.log(messageresponse); 
    deffered.fulfill(messageresponse); //Instead of returning the response message, fulfill the promise that we created early. 
    }); 

return deffered.promise; //return the created promise. 
}; 

你可以調用內部的任何測試的，將返回只有當響應從API調用收到它解決了諾言的generateToken（）方法。

it('Post a GET request and generate a response', function() { 
    var response = commonFunctionObj.generateToken(); 
    response.then(function(value){ 
    console.log(value); 
    }); 
}); 

Answer 2

你需要寫的回調函數，這是解決的承諾或處理異步行爲

Code Snippet: 

    it('Post a GET request and generate a response', function() { 
     var response = commonFunctionObj.generateToken(function(err,res){ 
          res.then(function(value){ 
           console.log(value); //or return value 
         }); 
       }); 
    }); 

Answer 3

我認爲你可以如下做到這一點的打印響應邏輯;

this.generateToken = function() { 
    var deferred = protractor.promise.defer(); 

    var options = { 
    uri: 'http://localhost:10000/token', 
    method: 'GET', 
    headers: { 
    'Authorization': "YWRtaW46YWRtaW4=" 
    }, 
    }; 
    request(options, function (error, response, body) { 
    var messageresponse = response.body.toString(); 

    deferred.fulfill(messageresponse); 
    }); 

    return deferred.promise; 
}; 


it('Post a GET request and generate a response', function() { 
    var response = commonFunctionObj.generateToken(); 
    response.then(function(value){  //Getting below mentioned error on this line 
     console.log(value); 
    }); 
}); 

說明;

您不能使用.then與generateToken的回報。因爲該函數內部沒有返回。你需要做出承諾（protractor.promise），然後在裏面使用。然後，您可以使用.then和generateToken函數。