Exercise - Demonstrate your knowledge of the new
keyword.
For this exercise, we’re challenging you to build a solution requiring you to use a number of the concepts you’ve learned so far. Have fun and enjoy!
Build a contract that can deploy copies of an address book contract on demand, which allows users to add, remove, and view their contacts.
You’ll need to develop two contracts for this exercise and import at least one additional contract.
Review the Ownable contract from OpenZeppelin. You’ll need to use it to solve this exercise.
You may wish to use another familiar contract to help with this challenge.
Create an Ownable
contract called AddressBook
. It includes:
struct
called Contact
with properties for:
id
firstName
lastName
uint
array of phoneNumbers
contacts
It should include the following functions:
The addContact
function should be usable only by the owner of the contract. It should take in the necessary arguments to add a given contact’s information to contacts
.
The deleteContact
function should be usable only by the owner and should delete the contact under the supplied _id
number.
If the _id
is not found, it should revert with an error called ContactNotFound
with the supplied id number.
The getContact
function returns the contact information of the supplied _id
number. It reverts to ContactNotFound
if the contact isn’t present.
Question
For bonus points (that only you will know about), explain why we can’t just use the automatically generated getter for contacts
?
The getAllContacts
function returns an array with all of the user’s current, non-deleted contacts.
You shouldn’t use onlyOwner
for the two get functions. Doing so won’t prevent a third party from accessing the information, because all information on the blockchain is public. However, it may give the mistaken impression that information is hidden, which could lead to a security incident.
The AddressBookFactory
contains one function, deploy
. It creates an instance of AddressBook
and assigns the caller as the owner of that instance. It then returns the address
of the newly-created contract.
Testnets are not permanent! Base Goerli will soon be sunset, in favor of Base Sepolia.
As these are separate networks with separate data, your NFTs will not transfer over.
Don’t worry! We’ve captured the addresses of all NFT owners on Base Goerli and will include them when we release the mechanism to transfer these NFTs to mainnet later this year! You can also redeploy on Sepolia and resubmit if you’d like!