Adding subjects to the command line app

Question

I started implementing the feature of choosing the subject to get the points for.This was easy but my problem was in displaying the error message.The error message is displayed for every user.But I only want to log it out once.

Here is app.js

var profile = require("./profile.js")


var subj = process.argv[2]
var users = process.argv.slice(3);


users.forEach(function(currentValue){

  profile.get(currentValue,subj)

})

Here is profile.js

//Print out message
var http = require("http");

var subjs;
var profile;

var printMessage =  function(username,badgeCount,points,subj){
  var message = username + " has " + badgeCount + " total badges and "+ points+ " points in "+subj;
  if(points === undefined ){

    console.error("The subject:("+subj+") does not exist.Please choose a valid subject.Subjects are case senitive.Here is a subject list :"+ subjs);
    return false;






    } else{
  console.log(message);
}}

//Print out ERROR messages
function printError(error){
   console.error(error.message);
}

function get(username,subj){
//connect to API URL(https://teamtreehouse.com/username.json)
var req = http.get("http://teamtreehouse.com/"+username+".json",function(response){


  var body="";
  //Read the data from the response
   response.on('data', function (chunk) {
    body += chunk;
  });

  //Parse the data 
     response.on('end',function(){
      if(response.statusCode === 200){

       try { profile = JSON.parse(body); 
         subjs = Object.keys(profile.points).splice(1);
    //Print the data out

    printMessage(username,profile.badges.length,profile.points[subj],subj);

  } catch(error){
    //Parsing Error
      printError(error);
   }
      }else{
        //StatusCode Error
        printError({message:"There was an error getting the profile for "+ username +" ("+http.STATUS_CODES[response.statusCode]+")" +" please try again later"})
      } 
     });


  //conncetion Error
  req.on("error",printError)
})
}


module.exports.get = get;

I know why it is displaying twice but I can not find any solution to displaying only once.

Answer 1 · 2015-01-02T17:55:14Z

January 2, 2015 5:55pm

Good idea, Hossam Khalifa .

One way to implement the display of the error message only once is explained below. The re-factored files, formatted and with comments, are pasted after the explanation.

This will be 2 step process - Step 1 will concentrate on handling the users array that was passed to start the app and Step 2 will focus on the subject that was passed to start the app.

Handling the users array
1. Declare variables to handle unknown user(s) error
2. Add a third parameter to get() function
3. Refactor parsing portion of get()
4. Create function to print unknown users error message
Handling the subject
1. Declare variables to handle unknown subject error
2. Refactor printMessage()
3. Refactor parsing portion of get() (again)

Step 1: Handling the users array

Declare variables to handle unknown user(s) error

In profile.js after var profile; and before the function declarations insert

// Used for status code error message output
// Array for users that were not found
var unknownUsers = [];
// Counter for users not returned
var counter = 0;

Add a third parameter to `get()` function

In app.js change profile.get(currentValue,subj) by adding a third variable (users.length) to the function call so it looks like:

profile.get(currentValue, subj, users.length)

In profile.js change the get() function declaration, in order to handle the third parameter, to:

// Add third parameter of numUsers
function get(username,subj, numUsers) {

Refactor parsing portion of `get()` in `profile.js`

Immediately following the line, response.on('end',function() { insert

// Increase the counter as we loop through the users array
counter ++;

Within the try block, after the printMessage() function call, insert

// Print error message of unknown/ not found users if there are any
printUnknownUsersError(counter, numUsers);

Within the else portion of the status code if statement replace the printError() function call with

// Add falsey username to array
unknownUsers.push(username);
// Print error message of unknown/ not found users if there are any
// We need to call this here in case all users were not found
printUnknownUsersError(counter, numUsers);

Create function to print unknown users error message

In profile.js above the get() function declaration add the following function:

function printUnknownUsersError(counter, numUsers) {
  // At the last item of users and at least 1 unknown user esixts
  if (counter === numUsers && unknownUsers.length > 0) {
    var message =  "\n"; // newline for spacing before this error message

    message += 'There was an error getting the profile for ';
    // Display the users in the order they were called initially and convert array to string
    message += unknownUsers.reverse().join(', ');
    // If statusCode is 200 (because at least one username was correctly returned)
    //     we make an assumption that if a username isn't found it's because it
    //     doesn't exist, i.e. Not Found error code message
    //     Similar to if no results were found and using http.STATUS_CODES[response.statusCode]
    message += ' (Not Found). Please check the spelling or try again later';

    //StatusCode Error
    printError({ message: message });
  // Not at end of users array so carry on
  } else {
    return;
  }
}

Step 2: Handling the subject

Declare variables to handle unknown subject error

In profile.js after var counter = 0; and before the function declarations insert

// Trigger for exit
var time2go = false;

Immediately following the line, response.on('end',function() {, but above counter ++;, insert

// Trigger for valid subject
var isSubj = false;

Refactor `printMessage()`

Our main goal here is to set time2go = true when an invalid subject is found so we can print the error message only once then exit the app
A secondary goal is to conform the usage of the message variable to sense of standards and readability, i.e.similar to how we utilized the variable of the same name in printUnknownUsersError()
Another secondary goal is to return the error message, which will be handled by the catch block (explained below), instead of printing to the console from within the function
Replace the current body of the printMessage() function with

 var message = "";
  // The subject given is invalid
  if(points === undefined) {
    // Print invalid subject message only once
    time2go = true;
    message += "\nThe subject:("; // Add a new line for readability
    // Attach the subject that was provided
    message += subj;
    message += ") does not exist. ";
    message += "Please choose a valid subject. Subjects are case senitive.";
    message += "\nHere is a subject list: ";
    // Attach the list of subjects and format so that a
    //     space follows the comma between valid subjects
    //     for better readability
    message += subjs.join(', ');
    // Send message to be output by error handler in catch block
    return {message: message};
  } else {
    // Print user's profile info
    message = username + " has " + badgeCount + " total badges and "+ points+ " points in "+subj;
    console.log(message);
  }

Refactor parsing portion of `get()` (again)

+Within response.on('end',function() { and after var isSubj = undefined;, but before counter++; insert

// Invalid subject so quit
      if (time2go) {
        return false;
      }

Within the try block, immediately after subjs = Object.keys(profile.points).splice(1);, but before the closing bracket of the try block, replace the code with

// Check existing subjects to verify if subj is valid
 for (var i = 0; i <= subjs.length; i++) {
   // Valid subject
   if (subjs[i] === subj) {
     isSubj = true;
   }
  }

  // Invalid subject
  if (!isSubj) {
    // Print the invalid subject message
    //     - Exit try block and send to catch block
    throw printMessage("", "", undefined, subj);
  } else {
    //Print the data out
    printMessage(username,profile.badges.length,profile.points[subj],subj);
    // Print error message of unknown/ not found users if there are any
    printUnknownUsersError(counter, numUsers);
  }

Files

app.js:

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

// Create String of potential subject
var subj = process.argv[2];
// Create Array of potential users
var users = process.argv.slice(3);

// Loop through each user, get their info and output
users.forEach(function(currentValue) {
  profile.get(currentValue,subj, users.length);
});

profile.js:

/* Retrieve a user's profile info
 * and
 * Print out message(s)
 */

var http = require("http");

// A user's returned profile
var profile = {};
// Array for existing subjects
var subjs = [];
// Array for users not returned
var unknownUsers = [];
// Counter for looping through provided users array
var counter = 0;
// Trigger for exit
var time2go = false;


function printMessage(username,badgeCount,points,subj) {
  var message = "";
  // The subject given is invalid
  if(points === undefined) {
    // Print invalid subject message only once
    time2go = true;
    message += "\nThe subject:("; // Add a new line for readability
    // Attach the subject that was provided
    message += subj;
    message += ") does not exist. ";
    message += "Please choose a valid subject. Subjects are case senitive.";
    message += "\nHere is a subject list: ";
    // Attach the list of subjects and format so that a
    //     space follows the comma between valid subjects
    //     for better readability
    message += subjs.join(', ');
    // Send message to be output by error handler in catch block
    return {message: message};
  } else {
    // Print user's profile info
    message = username + " has " + badgeCount + " total badges and "+ points+ " points in "+subj;
    console.log(message);
  }
}

function printUnknownUsersError(counter, numUsers) {
  // At the last item of users and at least 1 unknown user esixts
  if (counter === numUsers && unknownUsers.length > 0) {
    var message =  "\n"; // newline for spacing before this message

    message += 'There was an error getting the profile for ';
    // Display the users that were not found and convert array to string
    message += unknownUsers.join(', ');
    // If statusCode is 200 (because at least one username was correctly returned)
    //     we make an assumption that if a username isn't found it's because it
    //     doesn't exist, i.e. Not Found error code message
    //     Similar to if no results were found and using http.STATUS_CODES[response.statusCode]
    message += ' (Not Found). Please check the spelling or try again later';

    //StatusCode Error
    printError({ message: message });
  } else {
    // Not at end of users array so carry on
    return;
  }
}

//Print out Error messages
function printError(error) {
   console.error(error.message);
}

function get(username,subj, numUsers) {
  //connect to API URL(https://teamtreehouse.com/username.json)
  var req = http.get("http://teamtreehouse.com/" + username + ".json",function(response) {
    var body="";

    //Read the data from the response
    response.on('data', function (chunk) {
      body += chunk;
    });

    //Parse the data
    response.on('end',function() {
      // Trigger for valid subject
      var isSubj = false;

      // Invalid subject so quit
      if (time2go) {
        return false;
      }

      // Increase the counter as we iterate through the users array
      counter ++;

      if (response.statusCode === 200) {
        try {
          // Store the returned profile
          profile = JSON.parse(body);
          // Store a list of current subjects
          subjs = Object.keys(profile.points).splice(1);

            // Check existing subjects to verify if subj is valid
            for (var i = 0; i <= subjs.length; i++) {
              // Valid subject
              if (subjs[i] === subj) {
                isSubj = true;
              }
            }

            // Invalid subject
            if (!isSubj) {
              // Print the invalid subject message
              //     - Exit try block and send to catch block
              throw printMessage("", "", undefined, subj);
            } else {
              //Print the data out
              printMessage(username,profile.badges.length,profile.points[subj],subj);
              // Print error message of unknown/ not found users if there are any
              printUnknownUsersError(counter, numUsers);
            }

        } catch(error) {
          //Parsing Error
          printError(error);
        }

      } else {
          // Add falsey username to array
          unknownUsers.push(username);
          // Print error message of unknown/ not found users if there are any
          // We need to call this here in case all users were not found
          printUnknownUsersError(counter, numUsers);

      }
    });

    //Conncetion Error
    req.on("error",printError);
  });
}

// Expose method
module.exports.get = get;

Changelog:

Jan. 8, 2015: Added step 2 for handling of the bad subject error message to be output only once

Welcome to the Treehouse Community

Looking to learn something new?

Hossam Khalifa

Hossam Khalifa

Adding subjects to the command line app

1 Answer

Sean T. Unwin

Sean T. Unwin

Step 1: Handling the users array

Declare variables to handle unknown user(s) error

Add a third parameter to `get()` function

Refactor parsing portion of `get()` in `profile.js`

Create function to print unknown users error message

Step 2: Handling the subject

Declare variables to handle unknown subject error

Refactor `printMessage()`

Refactor parsing portion of `get()` (again)

Files

Changelog:

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Welcome to the Treehouse Community

Looking to learn something new?

Hossam Khalifa

Hossam Khalifa

Adding subjects to the command line app

1 Answer

Sean T. Unwin

Sean T. Unwin

Step 1: Handling the users array

Declare variables to handle unknown user(s) error

Add a third parameter to get() function

Refactor parsing portion of get() in profile.js

Create function to print unknown users error message

Step 2: Handling the subject

Declare variables to handle unknown subject error

Refactor printMessage()

Refactor parsing portion of get() (again)

Files

Changelog:

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Sean T. Unwin

Sean T. Unwin

Hossam Khalifa

Hossam Khalifa

Sean T. Unwin

Sean T. Unwin

Add a third parameter to `get()` function

Refactor parsing portion of `get()` in `profile.js`

Refactor `printMessage()`

Refactor parsing portion of `get()` (again)