Mercado Pokémon

Teaching material for Basic Ethereum for Developers Workshop

The featured content must be used only for educational purposes. This is a prototype for studying and learning about the development of Dapps (decentralized applications) and should not be used in production.

What is the Mercado Pokémon?

Mercado Pokémon is a demo of creating coins and Pokémons in Ethereum platform, as well as the trading between different accounts.

Also is presented the concept of a non-infrastructure environment, which uses blockchain as a data repository and acessing dapps directly by a standalone html.

Pre-requisites:

• Geth **
• Truffle (2.1.2)**
• TestRPC (problem with gas for pokemon contracts)
• Solidity Browser
• Ethereum wallet

Setup a ethereum private net:

1. Create the directory structure

   mkdir -p private_net/keystore
   

2. Copy the private key (password: abcd) to the keystore

   cp <truffle-mercado-pokemon>/support/UTC--2015-08-09T04-06-35.465758600Z--6a5b342ec71def8aac337b82969d9ddd811023c9 private_net/keystore
   

3. Start the blockchain with a new genesis

   geth --datadir ./private_net init <truffle-mercado-pokemon>/support/private_genesis.json
   

4. Start the node

   geth --fast --cache 512 -ipcpath ~/Library/Ethereum/geth.ipc --networkid 1234 --datadir ./private_net --unlock 0 --rpc --rpccorsdomain="*" --rpcaddr "0.0.0.0"
   

5. Unlock the account[0] with the password 'abcd'

6. On a new terminal, attach to the geth console

   geth attach
   miner.start(1)
   

Setup using Ethereum Wallet (for using Truffle, jump to the next section)

1. Open file accounts-for-testing.txt

2. Load contracts/pokecoin.sol in Ethereum Wallet (contracts > Deploy new contract) and use the demo account addresses from Player1 and Player2 to launch the contract. (2000000 gas)

3. Load contracts/pokecentral.sol in Ethereum Wallet and use the demo account addresses from Player1 and Player2 to launch the contract. (6000000 gas)

4. Write the Pokecoin and PokeCentral addresses on a notepad.

5. Load contracts/pokemarket.sol no Ethereum Wallet and use PokeCoinAddress and PokeCentralAddress to launch the contract. (6000000 gas)

6. Write the Pokemarket address on a notepad.

7. You must update PokeMarketAddress in the contracts PokeCoin e PokeCentral to enable access.

8. Update the variables PokeCoinAddress, PokeCentralAddress e PokeMarketAddress in javascripts/mercadopokemon.js

9. Load app/player1.html and app/player2.html in separate windows on Chrome browser.

Setup truffle

1. Go to the truffle-mercado-pokemon dir and open the Truffle console on a new terminal

   truffle console
   

2. Run the migrate to load contracts to blockchain

   migrate --reset
   

3. Update vars PokeCoinAddress, PokeCentralAddress and PokeMarketAddress in mercadopokemon.js

Using Mercado Pokemon

Open player1.html and player2.html each one in a new window in Chrome

Examples using Truffle console

1. Transfer pokecoins to the players 1 and 2 using the console:

   pokecoin.transfer(account1Demo, 5000, {from:web3.eth.accounts[0],gas:2000000});
   pokecoin.transfer(account2Demo, 5000, {from:web3.eth.accounts[0],gas:2000000});
   

   5.1 Verify is the transfers were suceeded

   pokecoin.balanceOf(account1Demo) // 5000
   pokecoin.balanceOf(account2Demo) // 5000
   

2. Create the next four valid pokemons:

   pokecentral.newPokemon(3,500,40, {from:web3.eth.accounts[0],gas:2000000});
   pokecentral.newPokemon(1,535,70, {from:web3.eth.accounts[0],gas:2000000});
   pokecentral.newPokemon(4,546,80, {from:web3.eth.accounts[0],gas:2000000});
   pokecentral.newPokemon(2,557,90, {from:web3.eth.accounts[0],gas:2000000});
   

   2.1 Verify pokemon total

   pokecentral.totalPokemonSupply() // 4
   

   2.2 Verify the pokemon owner (wait until mining)

   pokecentral.pokemons(0);
   pokecentral.pokemons(1);
   pokecentral.pokemons(2);
   pokecentral.pokemons(3);
   pokecentral.pokemons(4);
   

3. Transfer the pokemons to player1 and player2

   pokecentral.transferPokemon(web3.eth.accounts[0], account1Demo, 1,{from:web3.eth.accounts[0],gas:2000000});
   pokecentral.transferPokemon(web3.eth.accounts[0], account1Demo, 4,{from:web3.eth.accounts[0],gas:2000000});
   pokecentral.transferPokemon(web3.eth.accounts[0], account2Demo, 2,{from:web3.eth.accounts[0],gas:2000000});
   pokecentral.transferPokemon(web3.eth.accounts[0], account2Demo, 3,{from:web3.eth.accounts[0],gas:2000000});
   

   3.1 Verify the pokemon owner, as in 2.2

4. Update the PokeMarketAddress in dapps PokeCoin e PokeCentral

   pokecoin.updatePokeMarketAddress(pokemarket.address, {from:web3.eth.accounts[0],gas:2000000});
   pokecentral.updatePokeMarketAddress(pokemarket.address, {from:web3.eth.accounts[0],gas:2000000});
   

   4.1 Verify the addresses

   pokecoin.pokeMarketAddress();
   pokecentral.pokeMarketAddress();
   

5. Put the pokemon 1 from account1Demo for selling by 2000 pkc:

   pokemarket.newSale(account1Demo, 1, 2000, {from:web3.eth.accounts[0],gas:2000000});
   

6. Verify the number of active sells:

   pokemarket.totalActiveSales();
   

7. Verify the active sell 1 data:

   pokemarket.pokeSales(0);
   

8. Verify if the pokemon 1 is active for selling:

   pokemarket.pokeSelling(1);
   

9. Buy the pokemon 1, with the player 2

   pokemarket.buyPokemon(account2Demo, 1, {from:web3.eth.accounts[0],gas:2000000});
   

10. Verify if the pokemon owner was changed to account2Demo address

    pokecentral.pokemons(1);
    

11. Verify the pokecoins total for each player

    pokecoin.balanceOf(account1Demo);
    pokecoin.balanceOf(account2Demo);
    

   ```

How it works:

Once the contracts were loaded, we created the PokeCoins and Pokemons, and distributed them between Player1 and Player2 accounts. Through the html files you can put Pokemons for sale and make the purchase.

Obs:

It is necessary that the account [0] is unlocked and has funds. To do this, type: personal.unlockAccount(eth.accounts[0]) on the console.

If pokecoins are transferred to an account, you can trade them directly in the secondary market, but that wallet must have funds for paying the rsk gas transaction.