Before Trigger: System.NullPointerException: Attempt to de-reference a null object

Question

I'm trying to use an Apex trigger to associate Account.Name to a Contact from a community form. Here is my trigger,

trigger ContactBeforeInsert on Contact (before insert, after insert) {

    String USER_DOMAIN = '@example.com';
    Account defaultAccount = [SELECT Id, Name FROM Account WHERE Name = 'Example' LIMIT 1];
    List<User> users = new List<User>();
    List<Contact> updatedContacts = new List<Contact>();
    Profile communityProfileId = [SELECT Id FROM Profile WHERE Name = 'Customer Community User' LIMIT 1];

    if (Trigger.isInsert && defaultAccount != null && Trigger.New[0].registerAs__c != null) {
        if (Trigger.isBefore) {
            for (Contact contact : Trigger.New) {
                contact.Account.Name = defaultAccount.Name; // Errors out here.
                updatedContacts.add(contact);
            }
            insert updatedContacts;
        }

        else if (Trigger.isAfter && !updatedContacts.isEmpty()) {
            for (Contact contact :updatedContacts) {
                User user = new User(
                    ContactId = contact.Id,
                    Username = contact.FirstName + USER_DOMAIN,
                    LastName = Contact.LastName,
                    Email = contact.Email,
                    Alias = contact.FirstName,
                    TimeZoneSidKey = 'GMT',
                    LanguageLocaleKey = 'en_US',
                    EmailEncodingKey = 'UTF-8',
                    LocaleSidKey = 'en_US',
                    ProfileId = communityProfileId.Id,
                    isActive = true
                );
                Users.add(user);
            }
            insert Users; 
        }
    }
}

But when I create a contact from the form, I get an error ContactBeforeInsert: execution of BeforeInsert caused by: System.NullPointerException: Attempt to de-reference a null object Trigger.ContactBeforeInsert: line 17, column 1.

Line 17 is contact.Account.Name = defaultAccount.Name;. I have verified that the defaultAccount is not null. If I run the same query in the developer console, I do see my account fetched. What's wrong here? I am new to Salesforce and Apex and I am dealing with this issue for the past one day.

Answer 1

You cannot assign the account to a contact based on SObject, you will have to reference the Account's Id to the Contact's AccountId field with a key which is ID here.

If you need to add account in before insert add it like this:

contact.AccountId = defaultAccount.Id; // Errors out here.