How to create portal user in apex class?

I think we must have faced difficulty to create portal user in apex class. 

Below are the errors we might have faced. 

System.SObjectException: Field is not writeable: User.IsPortalEnabled 

System.SObjectException: Field is not writeable: User.Contact 

This post is just to tell how to create portal user. We already know that first we need to create Contact and Account , ensure the Account is a partner account, then create a user that points to the contact.

Still same error will come. 

Solution-

To make a partner portal account, we need to ensure the account's owner has the correct values in the UserRoleId and ProfileId fields.

To make a partner user, any user is ok. Simply ensure the user's profile is a Portal User profile. Then you can specify a value for its ContactId field.

Below is the code 

//Create portal account owner

UserRole portalRole = [Select Id From UserRole Where PortalType = 'None' Limit 1];

Profile profile1 = [Select Id from Profile where name = 'System Administrator'];

User portalAccountOwner1 = new User(

UserRoleId = portalRole.Id,

ProfileId = profile1.Id,

Username = System.now().millisecond() + 'test2@test.com',

    Alias = 'batman',

Email='bruce.wayne@wayneenterprises.com',

EmailEncodingKey='UTF-8',

Firstname='Bruce',

Lastname='Wayne',

LanguageLocaleKey='en_US',

LocaleSidKey='en_US',

TimeZoneSidKey='America/Chicago'

);

Database.insert(portalAccountOwner1);

//Create account

Account portalAccount1 = new Account(

Name = 'TestAccount',

OwnerId = portalAccountOwner1.Id

);

Database.insert(portalAccount1);

   

//Create contact

Contact contact1 = new Contact(

    FirstName = 'Test',

    Lastname = 'McTesty',

AccountId = portalAccount1.Id,

    Email = System.now().millisecond() + 'test@test.com'

);

Database.insert(contact1);

   

//Create user

Profile portalProfile = [SELECT Id FROM Profile WHERE Name LIKE '%Portal User%' Limit 1];

User user1 = new User(

Username = System.now().millisecond() + 'test12345@test.com',

ContactId = contact1.Id,

ProfileId = portalProfile.Id,

Alias = 'test123',

Email = 'test12345@test.com',

EmailEncodingKey = 'UTF-8',

LastName = 'McTesty',

CommunityNickname = 'test12345',

TimeZoneSidKey = 'America/Los_Angeles',

LocaleSidKey = 'en_US',

LanguageLocaleKey = 'en_US'

);

Database.insert(user1);