def add_data(self, data: str) -> bool:
"""
Adds a new Block to the Blockchain. Returns a bool indicating success or failure.
Parameters:
data -- the data (represented as a string) to be stored.
"""
timestamp = time.time()
# The previous hash is important since this is what helps us ensure
# that our Blockchain has not lost its integrity. Each block will
# keep track of the block before it, using its hash, thus we
# will know that no block has been tamperered with.
previous_hash = self.blocks[-1].generate_hash()
block = Block()
block.data = data
block.timestamp = timestamp
block.previous_hash = previous_hash
self.blocks.append(block)
# We validate the entire Blockchain to ensure that
# the block we just inserted did not break our
# Blockchain integrity.
if not self.validate():
self.blocks.remove(block)
return False
return True
def add_chain_data(self, chain_data: list):
"""
Takes a list of blocks, usually ingested from a JSON file, and adds them to the chain.
Parameters:
chain_data -- a list of dicts with "data", "previous_hash", "timestamp".
"""
for chain_item in chain_data:
block = Block()
block.data = chain_item["data"]
block.previous_hash = chain_item["previous_hash"]
block.timestamp = chain_item["timestamp"]
self.blocks.append(block)
def write_default_blockchain() -> str:
"""Returns the string representation of the default Blockchain data."""
genesis_block = Block()
genesis_block.data = "This is the sickest Blockchain implementation ever."
genesis_block.timestamp = time.time()
genesis_block.previous_hash = ""
# Create a temporary chain which we can convert to JSON.
default_chain = Blockchain([])
default_chain.blocks.append(genesis_block)
save_chain(default_chain)
return default_chain.to_json()
