遍历解析的JSON时变得不确定

Question

I have a function that checks whether the first name, last name and email of a new user is the same as what's in my node.js mock database (JSON file). It's failing because the email is undefined after the first iteration. ie If I add a user with duplicate email it will fail because the comparison db_email === email would never be true (after the first iteration).

What is happening? Am I missing something glaringly obvious?

db.json

[{"basic_info":{"first_name":"Diego","last_name":"Gonzalez","phone_number":"451-124-5112","postal_code":"G1F 1F5"},"address":{"email_address":"dgonz@gmail.com","street_no_and_name":"45 Kirklane Drive","city":"Rome","country":"Italy"},"banking_info":{"occupation":"accountant","annual_salary":45000,"monthly_expenses":2000},"products":{"chequing":true,"savings":true,"line_of_credit":false,"mortgage":true,"credit_card":true},"user_id":1},{"basic_info":{"first_name":"Marie","last_name":"Spitzer","phone_number":"640-998-3252","email_address":"mspitzer@gmail.com"},"address":{"street_no_and_name":"425 Godstone Lane","city":"Mexico City","country":"Mexico","postal_code":"Q1P 0F1"},"banking_info":{"occupation":"firefighter","annual_salary":95000,"monthly_expenses":5000},"products":{"chequing":false,"savings":false,"line_of_credit":false,"mortgage":false,"credit_card":true},"user_id":2},{"basic_info":{"first_name":"Jacob","last_name":"Karr","phone_number":"437-990-2275","email_address":"jacob.carr@carr.com"},"address":{"street_no_and_name":"23","city":"Rowena Drive","country":"Timbucktoo","postal_code":"M5H3P5"},"banking_info":{"occupation":"Consultant","annual_salary":"900001","monthly_expenses":"2440"},"products":{"Chequing":false,"Savings":false,"Line of Credit":false,"Mortage":false,"Credit Card":true},"user_id":3},{"basic_info":{"first_name":"Jacob","last_name":"Karr","phone_number":"437-990-2275","email_address":"jacob.carr@carr.com"},"address":{"street_no_and_name":"23","city":"Rowena Drive","country":"Timbucktoo","postal_code":"M5H3P5"},"banking_info":{"occupation":"Consultant","annual_salary":"900001","monthly_expenses":"2440"},"products":{"Chequing":false,"Savings":false,"Line of Credit":false,"Mortage":false,"Credit Card":true},"user_id":4}]

api.js

const validateRegistration = (fn, ln, email) => {
const reg = fs.readFileSync('db/registration.json', 'utf8');
const regObject = JSON.parse(reg);

const existingUsers = regObject.filter(userInfo => {
    const db_fn = userInfo["basic_info"]["first_name"];
    const db_ln = userInfo["basic_info"]["last_name"];
    const db_email = userInfo["address"]["email_address"];

    console.log(`${db_fn} === ${fn} = ${db_fn === fn}`);
    console.log(`${db_ln} === ${ln} = ${db_ln === ln}`);
    console.log(`${db_email} === ${email} = ${db_email === email}`);

    if (db_fn === fn && db_ln === ln && db_email === email) { return true; }
})

return existingUsers.length > 0 ? true : false;

}

console.log output

Diego === Jacob = false
Gonzalez === Karr = false
dgonz@gmail.com === jacob.carr@carr.com = false
Marie === Jacob = false
Spitzer === Karr = false
undefined === jacob.carr@carr.com = false
Jacob === Jacob = true
Karr === Karr = true
undefined === jacob.carr@carr.com = false

Thanks in advance for the help!

Answer 1

Figured it out; also feel quite stupid.

I placed 'email_address' under 'address' in the JSON where it should have been under 'basic_info'. Also should have been accessing it via const db_email = userInfo["basic_info"]["email_address"]; in api.js

Answer 2

This is expected javascript behavior: return undefined when a reference is not set.

You're JSON array does not necessarily have an 'email_address' field for every object, therefore 'undefined' is the value placeholder since it is not found.

Example of your user object[address] without an email_address:

"address":{"street_no_and_name":"23","city":"Rowena Drive","country":"Timbucktoo","postal_code":"M5H3P5"}

Answer 3

  {
    "basic_info": {
      "first_name": "Jacob",
      "last_name": "Karr",
      "phone_number": "437-990-2275",
      "email_address": "jacob.carr@carr.com"
    },
    "address": {
      "street_no_and_name": "23",
      "city": "Rowena Drive",
      "country": "Timbucktoo",
      "postal_code": "M5H3P5"
    },
    ...
    "user_id": 4
  }

Looks like email_address is actually nested under basic_info for all your users except the first.