polkadot-developers
diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/account-existence.js‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/account-existence.ts‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/asset-conversion-api.ts‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/dry-run-example.ts‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/tx-payment-api.ts‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/xcm-delivery-fees.ts‎
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diff --git a/‎.snippets/code/develop/interoperability/best-practices-for-teleporting-assets/xcm-execution-fees.ts‎
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@@ -0,0 +1,15 @@
+const { ApiPromise, WsProvider } = require('@polkadot/api');
+const provider = new WsProvider('wss://rpc.polkadot.io');
+const api = await ApiPromise.create({ provider });
+
+async function checkAccountExistence(api, address) {
+  const accountInfo = await api.query.system.account(address);
+  const balance = accountInfo.data.free.toBigInt();
+  const existentialDeposit = api.consts.balances.existentialDeposit.toBigInt();
+
+  return {
+    exists: !accountInfo.isEmpty,
+    balance,
+    hasExistentialDeposit: balance >= existentialDeposit,
+  };
+}
@@ -0,0 +1,16 @@
+import { dot } from '@polkadot-api/descriptors';
+import { createClient } from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+
+async function queryAccountBalance(address: string) {
+  const client = createClient(getWsProvider('wss://rpc.polkadot.io'));
+  const api = client.getTypedApi(dot);
+
+  const accountInfo = await api.query.System.Account.getValue(address);
+  const existentialDeposit = await api.constants.Balances.ExistentialDeposit();
+
+  return {
+    balance: accountInfo?.data.free ?? 0n,
+    hasED: (accountInfo?.data.free ?? 0n) >= existentialDeposit,
+  };
+}
@@ -0,0 +1,15 @@
+import { ah } from '@polkadot-api/descriptors';
+import { createClient } from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+
+const client = createClient(
+  getWsProvider('wss://asset-hub-paseo.dotters.network')
+);
+const api = client.getTypedApi(ah);
+
+const feeInAsset =
+  await api.apis.AssetConversionApi.quote_price_exact_tokens_for_tokens(
+    assetIn,
+    assetOut,
+    amountIn
+  );
@@ -0,0 +1,220 @@
+import {
+  ah,
+  myth,
+  XcmV3Junction,
+  XcmV3Junctions,
+  XcmV3MultiassetFungibility,
+  XcmV3WeightLimit,
+  XcmV4AssetAssetFilter,
+  XcmV4AssetWildAsset,
+  XcmV4Instruction,
+  XcmVersionedAssets,
+  XcmVersionedLocation,
+  XcmVersionedXcm,
+} from '@polkadot-api/descriptors';
+import {
+  createClient,
+  Enum,
+  FixedSizeBinary,
+  type Transaction,
+} from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+import { withPolkadotSdkCompat } from 'polkadot-api/polkadot-sdk-compat';
+
+// Asset Hub constants.
+const ASSET_HUB_WS_URL = 'ws://localhost:8000';
+const ASSET_HUB_PARA_ID = 1000;
+const ASSET_HUB_ACCOUNT = '15oF4uVJwmo4TdGW7VfQxNLavjCXviqxT9S1MgbjMNHr6Sp5';
+const DOT_UNITS = 10_000_000_000n; // 10 decimals.
+const DOT_CENTS = DOT_UNITS / 100n;
+
+// Mythos constants.
+const MYTHOS_WS_URL = 'ws://localhost:8001';
+const MYTHOS_PARA_ID = 3369;
+const MYTHOS_ACCOUNT = '0x69CF15A9393A0869A7fE535eCFe2C3CbaC127A40';
+const MYTH_UNITS = 1_000_000_000_000_000_000n; // 18 decimals.
+
+// Connect to Mythos.
+const mythosClient = createClient(
+  withPolkadotSdkCompat(getWsProvider(MYTHOS_WS_URL))
+);
+
+// Get the typed API which lets us use descriptors.
+const mythApi = mythosClient.getTypedApi(myth);
+
+// Build the teleport transaction.
+const tx = mythApi.tx.PolkadotXcm.limited_teleport_assets({
+  dest: XcmVersionedLocation.V4({
+    parents: 1,
+    interior: XcmV3Junctions.X1(XcmV3Junction.Parachain(ASSET_HUB_PARA_ID)),
+  }),
+  beneficiary: XcmVersionedLocation.V4({
+    parents: 0,
+    interior: XcmV3Junctions.X1(
+      XcmV3Junction.AccountId32({
+        id: FixedSizeBinary.fromAccountId32(ASSET_HUB_ACCOUNT),
+        network: undefined,
+      })
+    ),
+  }),
+  assets: XcmVersionedAssets.V4([
+    {
+      id: { parents: 0, interior: XcmV3Junctions.Here() },
+      fun: XcmV3MultiassetFungibility.Fungible(1n * MYTH_UNITS),
+    },
+  ]),
+  fee_asset_item: 0,
+  weight_limit: XcmV3WeightLimit.Unlimited(),
+});
+
+await dryRun(tx.decodedCall);
+
+async function dryRun(call: Transaction<any, any, any, any>['decodedCall']) {
+  // Dry run the teleport locally so you know you can for example withdraw
+  // the necessary funds and pay for delivery fees.
+  console.log('Dry running teleport on Mythos...');
+  const localDryRunResult = await mythApi.apis.DryRunApi.dry_run_call(
+    Enum('system', Enum('Signed', MYTHOS_ACCOUNT)),
+    call
+  );
+
+  // Only continue if the local dry run works.
+  // The first condition is whether or not the runtime API was successful,
+  // the second is whether or not the underlying dry-run was successful.
+  if (
+    localDryRunResult.success &&
+    localDryRunResult.value.execution_result.success
+  ) {
+    // You are interested in the message to Asset Hub that results from your call.
+    // You filter for it here.
+    const [_, messages] = localDryRunResult.value.forwarded_xcms.find(
+      ([location, _]) =>
+        // You happen to know the latest version in Mythos is V5 because of the descriptors.
+        location.type === 'V5' &&
+        location.value.parents === 1 &&
+        location.value.interior.type === 'X1' &&
+        location.value.interior.value.type === 'Parachain' &&
+        location.value.interior.value.value === ASSET_HUB_PARA_ID
+    )!;
+    // There could be multiple messages to Asset Hub, you know it's only one
+    // so you take the first one.
+    const messageToAh = messages[0];
+
+    // You connect to Asset Hub to dry run this message there.
+    const assetHubClient = createClient(getWsProvider(ASSET_HUB_WS_URL));
+    const ahApi = assetHubClient.getTypedApi(ah);
+
+    // You need to ensure it's V4 because V5 is not supported by Asset Hub at the time of writing.
+    // You get the supported versions directly from the descriptors.
+    if (messageToAh.type === 'V4') {
+      console.log('Dry running on Asset Hub...');
+      const remoteDryRunResult = await ahApi.apis.DryRunApi.dry_run_xcm(
+        XcmVersionedLocation.V4({
+          parents: 1,
+          interior: XcmV3Junctions.X1(XcmV3Junction.Parachain(MYTHOS_PARA_ID)),
+        }),
+        messageToAh
+      );
+
+      if (
+        remoteDryRunResult.success &&
+        remoteDryRunResult.value.execution_result.type === 'Complete'
+      ) {
+        // Success! Let's go ahead with the teleport.
+        console.log('Success!');
+      } else {
+        // It probably failed because your account doesn't exist on Asset Hub and
+        // You don't have DOT for the existential deposit.
+        // You should solve that problem and try again.
+        // You will later improve errors so that you know exactly what went wrong and can act accordingly.
+        // See https://github.com/paritytech/polkadot-sdk/issues/6119.
+        console.log('Failure :( Going to try again.');
+
+        // You're manually building an XCM here since you want to use the `ExchangeAsset` instruction
+        // to swap some of the MYTH for DOT to cover the existential deposit.
+        // This is executed via `PolkadotXcm.execute()` on Mythos and will send a message to Asset Hub.
+        const xcm = XcmVersionedXcm.V4([
+          // You withdraw some MYTH from your account on Mythos.
+          XcmV4Instruction.WithdrawAsset([
+            {
+              id: { parents: 0, interior: XcmV3Junctions.Here() },
+              fun: XcmV3MultiassetFungibility.Fungible(100n * MYTH_UNITS),
+            },
+          ]),
+          // Use them to pay fees.
+          XcmV4Instruction.BuyExecution({
+            fees: {
+              id: { parents: 0, interior: XcmV3Junctions.Here() },
+              fun: XcmV3MultiassetFungibility.Fungible(100n * MYTH_UNITS),
+            },
+            weight_limit: XcmV3WeightLimit.Unlimited(),
+          }),
+          // Teleport the MYTH to Asset Hub.
+          XcmV4Instruction.InitiateTeleport({
+            assets: XcmV4AssetAssetFilter.Wild(
+              XcmV4AssetWildAsset.AllCounted(1)
+            ),
+            dest: {
+              parents: 1,
+              interior: XcmV3Junctions.X1(
+                XcmV3Junction.Parachain(ASSET_HUB_PARA_ID)
+              ),
+            },
+            xcm: [
+              // You pay fees with MYTH on Asset Hub.
+              // This is possible because Asset Hub allows paying fees with any asset that has a liquidity pool.
+              XcmV4Instruction.BuyExecution({
+                fees: {
+                  id: {
+                    parents: 1,
+                    interior: XcmV3Junctions.X1(
+                      XcmV3Junction.Parachain(MYTHOS_PARA_ID)
+                    ),
+                  },
+                  fun: XcmV3MultiassetFungibility.Fungible(50n * MYTH_UNITS),
+                },
+                weight_limit: XcmV3WeightLimit.Unlimited(),
+              }),
+              // You explicitly swap your MYTH for 0.01 DOT to cover ED.
+              XcmV4Instruction.ExchangeAsset({
+                give: XcmV4AssetAssetFilter.Wild(
+                  XcmV4AssetWildAsset.AllCounted(1)
+                ),
+                want: [
+                  {
+                    id: { parents: 1, interior: XcmV3Junctions.Here() },
+                    fun: XcmV3MultiassetFungibility.Fungible(1n * DOT_CENTS),
+                  },
+                ],
+                maximal: false,
+              }),
+              // You deposit all your MYTH and your 0.01 DOT into the beneficiary account.
+              XcmV4Instruction.DepositAsset({
+                assets: XcmV4AssetAssetFilter.Wild(
+                  XcmV4AssetWildAsset.AllCounted(2)
+                ),
+                beneficiary: {
+                  parents: 0,
+                  interior: XcmV3Junctions.X1(
+                    XcmV3Junction.AccountId32({
+                      id: FixedSizeBinary.fromAccountId32(ASSET_HUB_ACCOUNT),
+                      network: undefined,
+                    })
+                  ),
+                },
+              }),
+            ],
+          }),
+        ]);
+
+        const tx = mythApi.tx.PolkadotXcm.execute({
+          message: xcm,
+          max_weight: { ref_time: 4_000_000_000n, proof_size: 300_000n },
+        });
+
+        // You try the dry run again.
+        dryRun(tx.decodedCall);
+      }
+    }
+  }
+}
@@ -0,0 +1,11 @@
+import { dot } from '@polkadot-api/descriptors';
+import { createClient } from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+
+const client = createClient(getWsProvider('wss://rpc.polkadot.io'));
+const api = client.getTypedApi(dot);
+
+const feeDetails = await api.apis.TransactionPaymentApi.query_fee_details(
+  call.toHex(),
+  call.encodedLength
+);
@@ -0,0 +1,11 @@
+import { dot } from '@polkadot-api/descriptors';
+import { createClient } from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+
+const client = createClient(getWsProvider('wss://rpc.polkadot.io'));
+const api = client.getTypedApi(dot);
+
+const deliveryFees = await api.apis.XcmPaymentApi.query_delivery_fees(
+  destination,
+  message
+);
@@ -0,0 +1,27 @@
+import { dot } from '@polkadot-api/descriptors';
+import { createClient } from 'polkadot-api';
+import { getWsProvider } from 'polkadot-api/ws-provider/web';
+
+const client = createClient(getWsProvider('wss://rpc.polkadot.io'));
+const api = client.getTypedApi(dot);
+
+const xcm = XcmVersionedXcm.V5([...]);
+
+// These will be set if the runtime API calls are successful.
+let localExecutionFees = 0;
+// We query the weight of the xcm.
+const weightResult = await api.apis.XcmPaymentApi.query_xcm_weight(xcm);
+if (weightResult.success) {
+    // We convert the weight to a fee amount.
+    // The asset is { parents: 1, interior: Here }, aka, DOT.
+    const executionFeesResult = await api.apis.XcmPaymentApi.query_weight_to_asset_fee(
+        weightResult.value,
+        XcmVersionedAssetId.V5({
+            parents: 1,
+            interior: XcmV3Junctions.Here(),
+        }),
+    );
+    if (executionFeesResult.success) {
+        localExecutionFees = executionFeesResult.value;
+    }
+}