Functions 1

• In this lesson, you will create a function to create developer card NTFs.
• You will work with events, SUI tokens and object tables.
• Events are important since they let the frontend know about the changes on the blockchain.
• We use object tables to store developer card NTFs.

You can access the codes we wrote in this lesson below. 👇

  // We are initating our contract.
  // DevHub created a shared object so that users can modify or alter their cards
  fun init(ctx: &mut TxContext) {
    transfer::share_object(
      DevHub {
        id: object::new(ctx),
        owner: tx_context::sender(ctx),
        counter: 0,
        cards: object_table::new(ctx),
      }
    );
  }

  // This function creates new card and adds it to the table
  public entry fun create_card(
    name: vector<u8>,
    title: vector<u8>,
    img_url: vector<u8>,
    years_of_exp: u8,
    technologies: vector<u8>,
    portfolio: vector<u8>,
    contact: vector<u8>,
    payment: Coin<SUI>,
    devhub: &mut DevHub,
    ctx: &mut TxContext
  ) {
    let value = coin::value(&payment); // get the tokens transferred with the transaction
    assert!(value == MIN_CARD_COST, INSUFFICIENT_FUNDS); // check if the sent amount is correct
    transfer::public_transfer(payment, devhub.owner); // tranfer the tokens

    // Here we increase the counter before adding the card to the table
    devhub.counter = devhub.counter + 1;

    // Create new id
    // Id is created here because we are going to use it with both devcard and the event
    let id = object::new(ctx);

    // Emit the event
    event::emit(
      CardCreated { 
        id: object::uid_to_inner(&id), 
        name: string::utf8(name), 
        owner: tx_context::sender(ctx), 
        title: string::utf8(title), 
        contact: string::utf8(contact) 
      }
    );

    // Creating the new DevCard
    let devcard = DevCard {
      id: id,
      name: string::utf8(name),
      owner: tx_context::sender(ctx),
      title: string::utf8(title),
      img_url: url::new_unsafe_from_bytes(img_url),
      description: option::none(),
      years_of_exp,
      technologies: string::utf8(technologies),
      portfolio: string::utf8(portfolio),
      contact: string::utf8(contact),
      open_to_work: true,
    };

    // Adding card to the table
    object_table::add(&mut devhub.cards, devhub.counter, devcard);
  }