Learning Blockchain through Python: Part 1

Blockchain is a big word and a confusing word to newbies. 

A blockchain is an online public bookkeeping ledger.

It automatically registers a financial transaction from the sender to the receiver.

Before we go into depth about the blockchain, let’s build a simple financial transaction from Python.

Here are the thought processes:

What information do you need to complete a transaction?

You will need:

👉 sender’s name

👉 receiver’s name

👉 amount to transact

How do you store the data with information?

In Python, dictionaries are preferable for transaction data storage since it is a set of key: value pairs that are searchable.

Construction a transaction

If Alice, the sender, sent $30 to Bob, the receiver, through a transaction, here is how to construct the data:

transaction1 = { ‘amount’: ‘30’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’}

More transactions

You can register more transactions by repeating the above method:

transaction2 = { ‘amount’: ‘200’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’}

transaction3 = { ‘amount’: ‘300’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ }

transaction4 = { ‘amount’: ‘300’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’ }

transaction5 = { ‘amount’: ‘200’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ }

transaction6 = { ‘amount’: ‘400’, ‘sender’: ‘Bob’, ‘receiver’: ‘Alice’ }

Combine all transactions together

Assume you will have six transactions total. You combine them together in one assigned variable, “mempool”:

mempool = [transaction1, transaction2, transaction3, transaction4, transaction5, transaction6]

Add one more transaction

Since there is a new transaction that needs to register in the blockchain, we can add through .append() :

my_transaction = { ‘amount’: ‘100’, ‘sender’: ‘Alice’, ‘receiver’: ‘Bob’ }

mempool.append(my_transaction)

Search transactions

Now, you have got your ledger input through Python manually!

You can search transactions whichever you want to. For instance, if you want the first 3 transactions, you can do:

block_transactions = mempool[0:3]

print(block_transactions)

Congratulation!

You got your blockchain! Although it does not automatically generate and capture transactions, you get your first blockchain at least!

You can have a code below:

transaction1 = {
  'amount': '30',
  'sender': 'Alice',
  'receiver': 'Bob'}
transaction2 = { 
  'amount': '200',
  'sender': 'Bob',
  'receiver': 'Alice'}
transaction3 = { 
  'amount': '300',
  'sender': 'Alice',
  'receiver': 'Bob' }
transaction4 = { 
  'amount': '300',
  'sender': 'Bob',
  'receiver': 'Alice' }
transaction5 = { 
  'amount': '200',
  'sender': 'Alice',
  'receiver': 'Bob' }
transaction6 = { 
  'amount': '400',
  'sender': 'Bob',
  'receiver': 'Alice' }

mempool = [transaction1, transaction2, transaction3, transaction4, transaction5, transaction6]

#1 add a new transaction
my_transaction = { 
  'amount': '100',
  'sender': 'Alice',
  'receiver': 'Bob' }

#2 add new transaction to the existing one
mempool.append(my_transaction)

#test print
#print(mempool)

#3 create a new list of addtional three new transactions

block_transactions = mempool[0:3]
print(block_transactions)