Transaction Configuration#

Example: Base USDC Transfer#

In this example, we’ll configure a transaction endpoint to transfer USDC tokens from our escrow wallet to a recipient. We’ll assume you’ve already created and funded an escrow wallet for the Base L2 network with BaseETH and that it contains some USDC tokens.

We’ll start by clicking the “Create a New Endpoint” button on the Transactions page. Give the endpoint a name and description, then select the Base L2 network from the dropdown. Fill in the webhook URL if you want to receive real-time feedback on the transaction status.

On the next page, we will enter transfer as the function name we want to call on the USDC contract address 0x833589fcd6edb6e08f4c7c32d4f71b54bda02913.

The transfer function on the USDC contract expects the following input parameters:

• to: The address to transfer the tokens to which is a primitive type address

• value: The amount of tokens to transfer (USDC has 18 decimal places) which is a primitive type uint256

We’ll set both of these parameters to be Dynamic so because we will pass both of them as input parameters when we call the API endpoit.

Transaction Parameters#

At the highest configuration level, input paramerters can be either primitive, array, or struct types. A primitive is a type like uint or bool that is not composed of other types and is likely the most common input type. An array is a collection of the same type of elements, and a struct is a collection of different types of elements.

Struct and Array Inputs#

If the function you want to call takes a struct or array as an input parameter, you’ll need to define the structure of the input in the transaction endpoint builder. Take the following example in which the input parameter is a struct which itself contains a uint128, string, and array of booleans:

struct Foo {
    uint128 fooUint128;
    string fooString;
    bool[] fooBoolArray;
}

function callFooBar(Foo calldata foo) public {
    emit CalledFoo(foo.fooUint128, foo.fooString, foo.fooBoolArray[0]);
}

The configuration for the input struct parameter, foo, would look like this:

The payload used to call the API endpoint would look like this:

{
    "params": {
        "foo": {
            "fooUint128": 123,
            "fooString": "Hello, World!",
            "fooBoolArray": [true, false, true]
        }
    }
}

Webhooks#

Webhooks are an optional configuration for you transaction endpoint but are highly recommended as they provide immediate feedback to your application once your transaction has been confirmed on the blochchain network. 1Shot implements best practices for webhooks are discussed at webhooks.fyi, which includes consumer verification, replay protection and forward compatibility. ,

When you configure a webhook, 1Shot will send a POST request to the URL you provide with a JSON payload containing the following fields:

• transactionHash: The hash of the transaction that was submitted to the blockchain

• status: The status of the transaction (pending, success, or failure)

• blockNumber: The block number the transaction was included in