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Store, instantiate, execute, and query contracts using `terrad`.

Requirements

Make sure you have set up the local network and that it is up and running:

You should also have the latest version of terradCopy terrad by building the latest version of Terra Core. You will configure terradCopy terrad to use it against your isolated testnet environment.

In a separate terminal, make sure to set up the following mnemonic:

BASH
terrad keys add test1 --recover

Using the mnemonic from the LocalNet guide.

Uploading Code

Make sure that the optimized build of my_first_contract.wasmCopy my_first_contract.wasm that you created in the last section is in your current working directory.

BASH
terrad tx wasm store artifacts/my_first_contract.wasm --from test1 --chain-id=localterra --gas=auto --gas-prices=28.325uluna --broadcast-mode=sync

Or, if you are on an arm64 machine:

BASH
terrad tx wasm store artifacts/my_first_contract-aarch64.wasm --from test1 --chain-id=localterra --gas=auto --gas-prices=28.325uluna --broadcast-mode=sync

This will ask for a confirmation before broadcasting to LocalTerra, type yCopy y and press enter.

You should see output similar to the following:

BASH
height: 6
txhash: 83BB9C6FDBA1D2291E068D5CF7DDF7E0BE459C6AF547EC82652C52507CED8A9F
codespace: ""
code: 0
data: ""
rawlog: '[{"msg_index":0,"log":"","events":[{"type":"message","attributes":[{"key":"action","value":"store_code"},{"key":"module","value":"wasm"}]},{"type":"store_code","attributes":[{"key":"sender","value":"terra1dcegyrekltswvyy0xy69ydgxn9x8x32zdtapd8"},{"key":"code_id","value":"1"}]}]}]'
logs:
- msgindex: 0
  log: ""
  events:
  - type: message
    attributes:
    - key: action
      value: store_code
    - key: module
      value: wasm
  - type: store_code
    attributes:
    - key: sender
      value: terra1dcegyrekltswvyy0xy69ydgxn9x8x32zdtapd8
    - key: code_id
      value: "1"
info: ""
gaswanted: 681907
gasused: 680262
tx: null
timestamp: ""

As you can see, your contract was successfully instantiated with Code ID #1.

You can check it out (this will download the wasm file from the network):

BASH
terrad query wasm code 1

Creating the Contract

You have now uploaded the code for your contract, but still don't have a contract. Create it with the following InitMsg:

JSON
{
  "count": 0
}

You can compress the JSON into 1 line with this online tool.

BASH
terrad tx wasm instantiate 1 '{"count":0}' --from test1 --chain-id=localterra --fees=28.325uluna --gas=auto --broadcast-mode=sync

You should get a response like the following:

BASH
height: 41
txhash: AEF6F2FA570029A5D4C0DA5ACFA4A2B614D5811E29EEE10FF59F821AFECCD399
codespace: ""
code: 0
data: ""
rawlog: '[{"msg_index":0,"log":"","events":[{"type":"instantiate_contract","attributes":[{"key":"owner","value":"terra1dcegyrekltswvyy0xy69ydgxn9x8x32zdtapd8"},{"key":"code_id","value":"1"},{"key":"contract_address","value":"terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5"}]},{"type":"message","attributes":[{"key":"action","value":"instantiate_contract"},{"key":"module","value":"wasm"}]}]}]'
logs:
- msgindex: 0
  log: ""
  events:
  - type: instantiate_contract
    attributes:
    - key: owner
      value: terra1dcegyrekltswvyy0xy69ydgxn9x8x32zdtapd8
    - key: code_id
      value: "1"
    - key: contract_address
      value: terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5
  - type: message
    attributes:
    - key: action
      value: instantiate_contract
    - key: module
      value: wasm
info: ""
gaswanted: 120751
gasused: 120170
tx: null
timestamp: ""

If the output does not contain detailed event logs, you need to query the chain for the transaction hash:

BASH
terrad query tx AEF6F2FA570029A5D4C0DA5ACFA4A2B614D5811E29EEE10FF59F821AFECCD399

From the output, you can see that your contract was created above at: terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5Copy terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5. Take note of this contract address, as you will need it for the next section.

Check out your contract information:

BASH
terrad query wasm contract terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5
address: terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5
owner: terra1dcegyrekltswvyy0xy69ydgxn9x8x32zdtapd8
codeid: 1
...

You can use the following command to decode any Base64 strings you see in responses or events:

BASH
echo eyJjb3VudCI6MH0= | base64 --decode

This for example will produce the message you used when initializing the contract:

JSON
{ "count": 0 }

Executing the Contract

Let's do the following:

  1. Reset count to 5
  2. Increment twice

If done properly, you should get a count of 7.

Reset

First, to reset:

JSON
{
  "reset": {
    "count": 5
  }
}
BASH
terrad tx wasm execute terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5 '{"reset":{"count":5}}' --from test1 --chain-id=localterra --fees=28.325uluna --gas=auto --broadcast-mode=sync

Incrementing

JSON
{
  "increment": {}
}
BASH
terrad tx wasm execute terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5 '{"increment":{}}' --from test1 --chain-id=localterra --gas=auto --fees=28.325uluna --broadcast-mode=sync

Querying count

Check the result of your executions!

JSON
{
  "get_count": {}
}
BASH
terrad query wasm contract-store terra18vd8fpwxzck93qlwghaj6arh4p7c5n896xzem5 '{"get_count":{}}'

Expected output:

TEXT
query_result:
  count: 7

Excellent! Congratulations, you've created your first smart contract, and now know how to get developing with the Terra Classic dApp Platform.

What's Next?

We've only walked through a simple example of a smart contract, that modifies a simple balance within its internal state. Although this is enough to make a simple dApp, you can power more interesting applications by emitting messages, which will enable you to interact with other contracts as well as the rest of the blockchain's module.

Check out a couple more examples of smart contracts using CosmWasm's smart contract repo.