Tezos is one of the oldest smart contract blockchains, with Ethereum being the very first.
While Ethereum is a popular choice among developers for developing and deploying smart contracts, its applications are not very scalable due to high fees and slow transactions. In contrast, Tezos applications are very efficient and inexpensive to set up.
In this guide, you will learn how to develop and deploy smart contracts in Tezos with SmartPy CLI. We will cover:
You can get the final project’s code in this GitHub repo.
To follow along with this article, you need to be familiar with the Tezos blockchain. Your knowledge doesn’t have to be in-depth.
Knowledge of the Ethereum blockchain is not required, but it helps a lot.
What is Tezos?
Tezos is a blockchain network and a smart contract platform that is built to be adaptive through its governance model and self-upgrading ability.
While Tezos and Ethereum are similar blockchains that support smart contracts and DApp development, they are different in several ways. The Tezos vs. Ethereum table below shows some of the differences between the two networks.
Tezos vs. Ethereum: A comparison chart
|Developers make proposals to upgrade the blockchain protocol on the network||Developers use a hardfork to upgrade the blockchain protocol|
|Stakeholders control upgrades to the blockchain protocol by voting to accept or decline proposals||The creators of the blockchain network govern upgrades to the blockchain protocol|
|Uses formal verification for executing smart contracts||Uses EVM to store and execute smart contracts on the network|
|Participants (nodes) have the option to provide computing resources or delegate their tokens to participate in validating transactions||All participants (nodes) must provide computing resources and stake their coins to participate in validating transactions|
|Gas fees are low, which makes it very scalable||Gas fees are really high, which makes it unscalable|
What is SmartPy?
SmartPy is a tool that allows you to build smart contracts easily on the Tezos blockchain.
You write contracts in SmartPy using Python. If you’re already familiar with Python, you don’t have to learn a new smart contract programming language.
SmartPy comes in two other variants that use other syntaxes: SmartTS, which uses TypeScript, and SmartML, which uses OCaml.
SmartPy compiles Python scripts to Michelson. Michelson is a low-level programming language for smart contracts in Tezos. SmartTS and SmartML can also be compiled using the SmartPy tool.
What are smart contracts?
Smart contracts are programs that you can build, deploy, and execute on a blockchain network. You don’t need to own a node on the network before deploying your smart contract.
With smart contracts, you can build applications accessible to all devices without owning or maintaining a server. These fully decentralised applications require little or no maintenance.
Smart contracts use the full potential of blockchains, allowing you to execute programs on the chain as well as to interact with the chain itself. You can hold or transfer tokens and access specialised functionality on the blockchain with a smart contract.
Getting started with SmartPy CLI
To install SmartPy CLI, run the command below:
$ bash <(curl -s https://smartpy.io/cli/install.sh)
This command creates a
smartpy-cli directory in
home with this tree structure:
More great articles from LogRocket:
smartpy-cli ├── browser.py ├── node_modules/ ├── originator.js ├── package.json ├── package-lock.json ├── __pycache__/ ├── smart.css ├── smart.js ├── smartpyc.js ├── smartpyc.py ├── smartpyio.py ├── smartpy.py ├── SmartPy.sh ├── smarttop/ ├── smart-ts-cli.js ├── templates/ ├── theme.js └── typography.css
To confirm the installation, run the following:
$ ~/smartpy-cli/SmartPy.sh --version
As an extra step to make
SmartPy.sh easily accessible, create an alias by copying the below into your
.bashrc file or related profile file:
$ alias smartpy="$HOME/smartpy-cli/SmartPy.sh"
Now you can use:
$ smartpy --version
$ ~/smartpy-cli/SmartPy.sh --version
This guide uses
tezos-client to interact with a deployed smart contract. To install
tezos-client, run one of the commands below, depending on whether you are using a Mac or Linux operating system:
# Mac $ brew tap serokell/tezos-packaging-stable https://github.com/serokell/tezos-packaging-stable.git $ brew install tezos-client # Linux $ wget https://github.com/serokell/tezos-packaging/releases/latest/download/tezos-client $ chmod +x tezos-client $ mkdir -p $HOME/.local/bin $ mv tezos-client $HOME/.local/bin $ echo 'export PATH="$HOME/.local/bin:$PATH"' >> $HOME/.bashrc $ source $HOME/.bashrc
Note that if you are using Windows, you need to install a Linux distro with wsl and run the Linux installation.
tezos-client, you need to set it up. Start by running the command below:
$ tezos-client --endpoint https://jakartanet.ecadinfra.com config update
This guide uses the Jarkatanet testnet to deploy and interact with a smart contract. The above command connects
tezos-client to the Jakartanet testnet through the node
https://jakartanet.ecadinfra.com on the network.
Before you perform any operation with
tezos-client, you need to connect an account. Tezos provides Faucet accounts that allow you to interact with the network for free.
You need to visit the Jakartanet Faucet website and download the Faucet file. After doing that, open the download folder in your terminal and run this command:
$ tezos-client activate account faucet with ./jakartanet.json
The command activates the Faucet account in your
tezos-client and gives it an alias
faucet. To check the balance for this account, open the
jakartanet.json file, copy the value of
pkh, then run this command:
$ tezos-client get balance for <address>
<address> with the
pkh value that you copied.
Note that Tezos Faucet accounts are publicly available to everyone and have a limited amount of Tez tokens, so you have to regulate your usage.
Developing a Tezos smart contract with SmartPy
To begin creating our example smart contract, create a new
store_text.py file and copy the below into it:
import smartpy as sp class StoreText(sp.Contract): def __init__(self, value): self.init(text = value) @sp.entry_point def replace(self, params): self.data.text = params.text @sp.entry_point # Note: the spaces before "@" def append(self, params): self.data.text += params.text
Here’s how the above contract works, piece by piece:
First, we imported the
import smartpy as sp
Then, we defined a class that extends
Lastly, we defined a few items within the smart contract; first, a constructor to initialise
def __init__(self, value): # Note: the spaces before "def" self.init(text = value)
Second, an entry point to replace the value of
@sp.entry_point # Note: the spaces before "@" def replace(self, params): self.data.text = params.text
Third, an entry point to append a string to
@sp.entry_point # Note: the spaces before "@" def append(self, params): self.data.text += params.text
Next, let’s take a look at how to test the smart contract.
Testing the Tezos smart contract
Smart contracts that are deployed to Tezos cannot be changed or removed. This can be a problem because there could be errors in the contract, and errors could lead to costly mistakes and the loss of funds.
SmartPy gives you the ability to easily test your contract before deploying. Testing the contract doesn’t require any tokens or a wallet account to run. All you need to do is open the
store_text.py file and copy the below below it:
@sp.add_test(name = "StoreText") def test(): scenario = sp.test_scenario() contract = StoreText("Hello") scenario += contract scenario.verify(contract.data.text == "Hello") contract.replace(text = "Hi") contract.append(text = ", there!") scenario.verify(contract.data.text == "Hi, there!")
Here’s how the snippet works. First, we registered a the
test function as a test script:
@sp.add_test(name = "StoreText")
Then, we defined the
In the remaining lines, we created a test scenario:
scenario = sp.test_scenario()
Initialized the contract with
contract = StoreText("Hello")
Added the contract instance to the scenario:
scenario += contract
Verified that the contract’s
text value is
scenario.verify(contract.data.text == "Hello")
append entry points:
contract.replace(text = "Hi") contract.append(text = ", there!")
And finally, verified that the contract’s
text value is now
scenario.verify(contract.data.text == "Hi, there!")
After adding the test, save the file and run this command:
$ ~/smartpy-cli/SmartPy.sh test store_text.py ./test-output
If the test is successful, the compiler won’t throw an error message.
Compiling the smart contract to Michelson
Before you deploy your smart contract, you need to compile it to Michelson. As mentioned earlier, Michelson is a low-level programming language used for smart contracts on the Tezos blockchain.
store_text.py, run the following:
$ ~/smartpy-cli/SmartPy.sh compile message.py ./output
If it compiled successfully, you should see an
output folder like the one below:
output/ ├── scenario.json ├── script_init.py ├── script_pure.py └── storeMessage/ ├── log.txt ├── step_000_cont_0_contract.json ├── step_000_cont_0_contract.py ├── step_000_cont_0_contract.tz ├── step_000_cont_0_sizes.csv ├── step_000_cont_0_storage.json ├── step_000_cont_0_storage.py ├── step_000_cont_0_storage.tz └── step_000_cont_0_types.py
output directory contains all the files necessary to deploy the smart contract.
Deploying the Tezos smart contract
store_text.py, open the
output/storeMessage folder in the terminal and run the command below:
$ ~/smartpy-cli/SmartPy.sh originate-contract --code step_000_cont_0_contract.json --storage step_000_cont_0_storage.json --rpc https://jakartanet.ecadinfra.com [INFO] - Using RPC https://jakartanet.ecadinfra.com/... [INFO] - Contract KT1………………CAjjW originated!!!
Here’s is how the command works:
tezos-clientto deploy (“originate”) a contract
--code step_000_cont_0_contract.jsonpoints to the compiled contract file
--storage step_000_cont_0_storage.jsonpoints to the compiled storage file
--rpc https://jakartanet.ecadinfra.compoints to an RPC node on the network you are deploying to
Tezos smart contracts usually involve two components: the storage and the contract. The storage holds the data that the contract stores, and the contract holds the logic of the smart contract.
Note that you can deploy the contract with any of the contract or storage compilations. They just have to be the same file extension when you are using the command.
By default, if you’re deploying on a testnet, the compiler will use a Faucet account. If you are deploying to the mainnet or you want to use your wallet account, add the
--private-key flag followed by the account’s private key.
Interacting with the deployed smart contract
Before interacting with the deployed smart contract, you need to know how the contract currently looks. To do that, open the SmartPy Explorer in your browser and follow these steps:
- Navigate to “Alternative Nodes”
- Paste the contract’s address in the “Contract” input
- Under “Explore on a Specific Node,” switch from
- Paste the RPC URL
https://jakartanet.ecadinfra.comto the text box
- Click on “Explore on a Specific Node”
When the contract data has appeared, the text storage should display as “Hello, There!”
Now that you know the contract’s text, you can change it to “Hi, There!” by calling the
replace entrypoint with this command:
$ tezos-client transfer 0 from faucet to <contract-address> --entrypoint replace --arg '"Hi, There!"'
If the command was successful, when you refresh the explorer, the storage should now display “Hi, There!”
Note that you must replace
<contract-address> with the address of the deployed contract before running the command.
This article covers the process of building smart contracts on Tezos with SmartPy. Building smart contracts allows you to take full advantage of the blockchain network to build decentralised applications and organisations.
I hope this article helped you understand the process of building smart contracts on Tezos. If you’d like to read more about smart contracts, check out this article about smart contract mistakes to avoid.
Thanks for reading! And have a nice day.Developing and deploying Tezos smart contracts
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