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KryptoJobs2Go Application

Instructions

The instructions for this Challenge are divided into the following high-level steps:

  1. Import Ethereum Transaction Functions into the KryptoJobs2Go Application
  2. Sign and Run a Payment Transaction
  3. Inspect the Transaction in Ganache

Step 1: Import Ethereum Transaction Functions into the KryptoJobs2Go Application

In this section, you'll import several functions from the crypto_wallet.py file into the fintech_finder.py file. Note that the latter file contains the code for the customer interface of the KryptoJobs2Go application. You’ll import the functions to add wallet operations to this application. In this section, you’ll also assume the role of a KryptoJobs2Go customer (that is, you’ll provide your Ethereum wallet and account information to the application).

To do all this, complete the following steps:

  1. Review the code in the crypto_wallet.py file. Note that the Ethereum transaction functions that you’ve built throughout this module have been incorporated into Python functions that allow you to automate the process of accessing them. The Ethereum transaction functions include wallet, wallet.derive_acount, get_balance, fromWei, estimateGas, sendRawTransaction, and others.

  2. Add your mnemonic seed phrase (which Ganache provided) to the SAMPLE.env file. Then rename the file to .env.

  3. Open the fintech_finder.py file. Near the beginning of the file, after the provided import statements, import the following functions from the crypto_wallet.py file:

    • generate_account
    • get_balance
    • send_transaction

  4. In the Streamlit sidebar section of code, create a variable named account. Set this variable equal to a call to the generate_account function. Note that this function will create the hierarchical deterministic (HD) wallet and the Ethereum account of the KryptoJobs2Go customer (in this case, you).

  5. In the same section of code, define a new st.sidebar.write function that displays the balance of the customer account. In this function, call the get_balance function, and pass it your Ethereum account.address.

Step 2: Sign and Run a Payment Transaction

In this section, you'll write the code to calculate the wage, in ether, of a fintech professional. The code will base this wage on both the professional’s hourly rate and the number of hours that they worked for a customer. Note that candidate_database in fintech_finder.py contains the hourly rates.

You’ll then write the code that uses the calculated wage to send a transaction that pays the professional. This code should allow the KryptoJobs2Go customer to authorize the transaction with their digital signature. To test this application, you’ll use your own Ethereum account information as the customer account information.

To do all this, complete the following steps:

  1. Note that a KryptoJobs2Go customer will first select a fintech professional candidate from the drop-down menu in the application interface. The customer will then enter the amount of time that they’ll hire the professional for. Code the application so that when a customer completes those steps, it calculates the wage, in ether, that the professional will get paid. To do so, complete the following steps:

    • Write the equation that calculates the candidate’s wage. This equation should get the candidate’s hourly rate from the candidate database (candidate_database[person][3]) and then multiply that by the value of the hours variable. Save output of this calculation in a variable named wage.
    • Write the wage variable to the Streamlit sidebar by using st.sidebar.write.

  2. Write the code that allows a customer (in this case, you) to send an Ethereum blockchain transaction that pays the hired candidate. To do so, first find the following code: if st.sidebar.button("Send Transaction"). Next, add logic to that if statement to send the appropriate information to the send_transaction function. To do so, complete the following steps:

    • Call the send_transaction function, and pass it the following three parameters:
      • Your Ethereum account information. Recall that this account instance got created when the generate_account function was called. And from the account instance, the application will be able to access the account.address information that it needs to populate the from data attribute in the raw transaction.
      • The candidate_address value. Note that this will get created and identified in the sidebar when a customer selects a candidate. It will populate the to data attribute in the raw transaction.
      • The wage value. This will get passed to the toWei function to determine the value, in wei, of the payment in the raw transaction.

Rewind: Recall that you imported the send_transaction function from the crypto_wallet file.

  1. Save the transaction hash, which the send_transaction function returns, as a variable named transaction_hash, and then display it in the web interface of the application.

Step 3: Inspect the Transaction in Ganache

In this section, you’ll test the KryptoJobs2Go application with your newly integrated Ethereum wallet. Specifically, you’ll send a test transaction by using the web interface of the application, and then look up the resulting transaction in Ganache.

To do so, complete the following steps:

  1. In the terminal, navigate to the project folder that contains your .env, fintech_finder.py, and crypto_wallet.py files. If your Conda dev environment isn’t already active, activate it.

  2. To launch the Streamlit application, type streamlit run fintech_finder.py, and then press Enter.

  3. On the resulting webpage, on the appropriate drop-down menu, select a candidate that you want to hire. Then enter the number of hours that you want to hire them for. (Remember that you don’t have lots of ether in your account, so you can’t hire them for too long.)

  4. Click the Send Transaction button to sign and send the transaction with your Ethereum account information. Then navigate to the Transactions section in Ganache and complete the following steps:

    • Take a screenshot of your address balance and history in Ganache. Save this screenshot in the README.md file of your GitHub repository for this Challenge assignment.
    • Take a screenshot of the transaction details in Ganache. Save this screenshot in the same README.md file.
    • Return to the original transaction, click the To address of the transaction, and then complete the following step:
      • Take a screenshot of the recipient’s address balance and history in Ganache. Save this screenshot to the README.md file.