dynamic.eg.ts

/**
 * @title Dynamic Usage
 * @description You may want to write code whose target chain is unknown before
 * runtime. A common example of this is block explorers. Use cases such as this
 * are "dynamic" in that they require one to read the chain's metadata at runtime
 * in order to derive the means of interacting with that chain. Dynamic usage of
 * Capi entails a subtly-different DX compared to that of chain-specific (codegen)
 * usage. There are three key differences:
 *
 * 1. We manually initialize the `ChainRune`.
 * 2. We manually access bindings.
 * 3. Chain-specifics are untyped (be wary to supply the correct data, as the checker is on vacation).
 */

import { $, ChainRune, WsConnection } from "capi"

/// We could also initialize a `ChainRune` with `WsConnection` and an RPC node WebSocket URL.
const chain = ChainRune.from(WsConnection.bind("wss://rpc.polkadot.io"))

/// Create a binding to the `System` pallet.
const System = chain.pallet("System")

/// Create a binding to the `Account` storage map.
const Account = System.storage("Account")

/// Read the first ten entries of the `Account` storage map.
/// Note how the lack of partial key is communicated via `null`.
const entries = await Account.entries({ limit: 10 }).run()

/// The result should contain a `[Uint8Array, AccountInfo]` tuple of length 10.
console.log("Entries page:", entries)
$.assert(
  $.sizedArray(
    $.tuple(
      $.sizedUint8Array(32),
      $.object(
        $.field("nonce", $.u32),
        $.field("consumers", $.u32),
        $.field("providers", $.u32),
        $.field("sufficients", $.u32),
        $.field(
          "data",
          $.object(
            $.field("free", $.u128),
            $.field("reserved", $.u128),
            $.field("frozen", $.u128),
            $.field("flags", $.u128),
          ),
        ),
      ),
    ),
    10,
  ),
  entries,
)