Fetch Network
Working with contracts
Contract interaction

Contract Interaction


Contract interactions, in blockchains networks, refers to the process of communicating with deployed smart contracts. This involves querying contract information or executing specific functions defined within the contract. Interactions can include tasks ranging from checking balances to transferring tokens, and so on.

Profiles provide network and contract configurations, while dynamic methods simplify common tasks. Scripts automate interactions for programmatic tasks. This interaction is vital for utilizing decentralized applications and services offered by smart contracts on the blockchain.

Start an interaction

You can interact with your project's contracts by using the shell or run commands.

Getting started

You can reproduce the examples provided here, by initially adding and compiling a basic starter ↗ī¸ (opens in a new tab) contract and a cw-20 token contract ↗ī¸ (opens in a new tab) to your project with the following commands:

jenesis add contract starter my_first_contract -d deployment_1
jenesis add contract cw20-base my_token -d token_1
jenesis compile

For more information on contract template examples, visit Jenesis Templates ↗ī¸ (opens in a new tab)

Interactive shell

You can open a shell within which you can easily start an interaction with your contracts, by simply running:

jenesis shell

If a profile is not selected, the default profile will be selected automatically. You can specify any profile using the --profile optional argument:

jenesis shell --profile my_profile

You will observe the following text indicating the available contracts in your project:

Network: fetchai-testnet
Detecting contracts...
C deployment_1
C token_1
Detecting contracts...complete

jenesis shell currently requires that contract names use accepted python variable names. For example, using token-1 instead of token_1 will generate an error when trying to interact with it.**

In this case, we can see that deployment_1 and token_1 deployments are available for this project. If these contracts have been already deployed, you can directly interact with them by performing contract queries and executions, such as:

>>> deployment_1.query(args = {'msg_name': {...}}
>>> deployment_1.execute(args = {'msg_name': {...}}

A ledger client (ledger) and your locally stored wallet keys will also be available in the shell. For example, if you have a local key named alice, you will find this under wallets['alice'] and you can query the balance as follows:

>>> ledger.query_bank_balance(wallets['alice'])

If the ledger is a testnet with a faucet URL, you can get funds using the faucet:

>>> faucet.get_wealth(wallets['alice'])

Dynamic methods

Jenesis also attaches the contract query, execution and deploy messages as dynamic methods.

For instance, the following query:

>>> token_1.query({"balance": {"address": str(wallet.address())}}))

can also be run as follows:

>>> token_1.balance(address=str(wallet.address()))
{'balance': '4000'}

Similarly, instead of using token_1.execute..., a transfer can be executed with the following:

>>> token_1.transfer(amount='1000', recipient=str(wallet2.address()), sender=wallet)

Additionally, Jenesis has an autocompletion helper for query, execution and deployment arguments. It will show automatically when typing in the shell.

We will now show an example assuming that token_1 deployment contract has only been compiled and not yet deployed, going through deployment, execution, and querying using dynamic methods.

For this example, we will first generate two wallets. We provide wealth to the sender wallet in atestfet so it can pay for transaction fees:

>>> wallet = LocalWallet.generate()
>>> wallet2 = LocalWallet.generate()
>>> faucet.get_wealth(wallet)

We can then proceed to deploy my_token contract using token_1 deployment configuration. We define the arguments for the CW-20 token: name, symbol, decimal, and the address that will be funded with these CW-20 tokens. In this case, we will fund wallet's address with 5000 tokens:

>>> token_1.deploy(name="Crab Coin", symbol="CRAB", decimals=6, initial_balances=[{ "address": str(wallet.address()), "amount" : "5000"}], sender=wallet)

We can query wallet balance to make sure it has been funded with cw20 tokens. Run the following:

>>> token_1.balance(address=str(wallet.address()))
{'balance': '5000'}

We can now execute a CW-20 token transfer of 1000 tokens from wallet to wallet2:

>>> token_1.transfer(amount='1000', recipient=str(wallet2.address()), sender=wallet)

Finally, we query both wallets' balance:

>>> token_1.balance(address=str(wallet.address()))
{'balance': '4000'}
>>> token_1.balance(address=str(wallet2.address()))
{'balance': '1000'}

We can observe that wallet has sent 1000 tokens to wallet2.

Executing scripts

You can also assemble the above commands into a script that is executable by the run command, in the following way:

from cosmpy.aerial.wallet import LocalWallet
wallet = LocalWallet.generate()
wallet2 = LocalWallet.generate()
token_1.deploy(name="Crab Coin", symbol="CRAB", decimals=6, initial_balances=[{ "address": str(wallet.address()), "amount" :  "5000"}], sender=wallet)
print("wallet initial cw20 MT balance: ", token_1.balance(address=str(wallet.address())))
tx = token_1.transfer(amount='1000', recipient=str(wallet2.address()), sender=wallet)
print("transfering 1000 cw20 MT tokens from wallet to wallet2")
print("wallet final cw20 MT balance: ", token_1.balance(address=str(wallet.address())))
print("wallet2 final cw20 MT balance: ", token_1.balance(address=str(wallet2.address())))

If you paste the above code into the file script.py inside the project's directory, you can run it with:

jenesis run script.py

And you will observe the same output as before. You can also specify the profile as an optional argument using --profile.

Finally, you can pass arguments to the script just as you would to a standard Python script by placing all the arguments to the script after the -- delimiter:

jenesis run script.py [--profile profile_name] -- arg1 arg2 --key1 value1 --key2 value2

For a better understanding, visit the CosmPy ↗ī¸ documentation for more contract interaction examples.

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