Your First Transaction
Last updated
Last updated
This tutorial describes how to generate and submit transactions to the Aptos blockchain, and verify these submitted transactions. The transfer-coin example used in this tutorial is built with the Aptos SDKs.
Install your preferred SDK from the below list:
Clone the aptos-core repo:
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Navigate to the Typescript SDK examples directory:
Install the necessary dependencies:
An output very similar to the following will appear after executing the above command:
The above output demonstrates that the transfer-coin example executes the following steps:
Initializing the REST and faucet clients.
The creation of two accounts: Alice and Bob.
The funding and creation of Alice's account from a faucet.
The creation of Bob's account from a faucet.
The transferring of 1000 coins from Alice to Bob.
The 54100 coins of gas paid for by Alice to make that transfer.
Another transfer of 1000 coins from Alice to Bob.
The additional 54100 coins of gas paid for by Alice to make that transfer.
Now see the below walkthrough of the SDK functions used to accomplish the above steps.
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SEE THE FULL CODE
In the first step, the transfer-coin example initializes both the REST and faucet clients:
The REST client interacts with the REST API.
The faucet client interacts with the devnet Faucet service for creating and funding accounts.
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Using the API client we can create a CoinClient that we use for common coin operations such as transferring coins and checking balances.
common.ts initializes the URL values as such:
TIP
By default, the URLs for both the services point to Aptos devnet services. However, they can be configured with the following environment variables:
APTOS_NODE_URL
APTOS_FAUCET_URL
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In Aptos, each account must have an on-chain representation in order to receive tokens and coins and interact with other dApps. An account represents a medium for storing assets; hence, it must be explicitly created. This example leverages the Faucet to create and fund Alice's account and to create but not fund Bob's account:
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In this step, the SDK translates a single call into the process of querying a resource and reading a field from that resource.
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Behind the scenes, the checkBalance function in CoinClient in the SDK queries the CoinStore resource for the AptosCoin and reads the current stored value:
Like the previous step, this is another helper step that constructs a transaction transferring the coins from Alice to Bob. For correctly generated transactions, the API will return a transaction hash that can be used in the subsequent step to check on the transaction status. The Aptos blockchain does perform a handful of validation checks on submission; and if any of those fail, the user will instead be given an error. These validations use the transaction signature and unused sequence number, and submitting the transaction to the appropriate chain.
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Behind the scenes, the transfer function generates a transaction payload and has the client sign, send, and wait for it:
Within the client, generateSignSubmitTransaction is doing this:
Breaking the above down into pieces:
The Move function is stored on the coin module: 0x1::coin.
Because the Coin module can be used by other coins, the transfer must explicitly specify which coin type to transfer. If not specified with coinType it defaults to 0x1::aptos_coin::AptosCoin.
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In TypeScript, just calling coinClient.transfer is sufficient to wait for the transaction to complete. The function will return the Transaction returned by the API once it is processed (either successfully or unsuccessfully) or throw an error if processing time exceeds the timeout.
You can set checkSuccess to true when calling transfer if you'd like it to throw an error if the transaction was not committed successfully:
Run the example:
The transfer-coin example code uses helper functions to interact with the . This section reviews each of the calls and gives insights into functionality.
See the TypeScript for the complete code as you follow the below steps.
The next step is to create two accounts locally. represent both on and off-chain state. Off-chain state consists of an address and the public/private key pair used to authenticate ownership. This step demonstrates how to generate that off-chain state.
transfer internally is a EntryFunction in the , i.e. an entry function in Move that is directly callable.