Blueprint

A BlueprintPromise works similarly to a CodePromise. It manages calls to the instantiate dispatchable in the contracts pallet and uses a code hash to retrieve previously uploaded contract code from chain storage. If a non-existent codeHash is used, the instantiation will fail on-chain.

Let's take for example an ink! flipper contract, the tx.<constructorName> interface is a normal submittable extrinsic with the result containing an actual ContractPromise instance, containing the address of the new contract.

import { BlueprintPromise } from '@polkadot/api-contract';

const blueprint = new BlueprintPromise(api, metadata, codeHash);

const tx = blueprint.tx.default({ gasLimit, storageDepositLimit, salt });

let address;

const unsub = await tx.signAndSend(alicePair, ({ contract, status }) => {
  if (status.isInBlock || status.isFinalized) {
    address = contract.address.toString();
    unsub();
  }
});

We have made it this far. At this point you should be familiar with code deployments as well as contract instantiation, next up we will read a contract value.