3 files changed, 30 insertions, 2 deletions
diff --git a/packages/order-utils/src/asset_data_utils.ts b/packages/order-utils/src/asset_data_utils.ts
index 18c1f93b6..3741a683e 100644
--- a/packages/order-utils/src/asset_data_utils.ts
+++ b/packages/order-utils/src/asset_data_utils.ts
@@ -1,4 +1,11 @@
-import { AssetProxyId, ERC20AssetData, ERC721AssetData, MultiAssetData, SingleAssetData } from '@0x/types';
+import {
+    AssetProxyId,
+    ERC20AssetData,
+    ERC721AssetData,
+    MultiAssetData,
+    MultiAssetDataWithRecursiveDecoding,
+    SingleAssetData,
+} from '@0x/types';
 import { AbiEncoder, BigNumber } from '@0x/utils';
 import { MethodAbi } from 'ethereum-types';
 import * as _ from 'lodash';
@@ -115,6 +122,26 @@ export const assetDataUtils = {
         };
     },
     /**
+     * Decodes a MultiAsset assetData hex string into it's corresponding amounts and decoded nestedAssetData elements (all nested elements are flattened)
+     * @param assetData Hex encoded assetData string to decode
+     * @return An object containing the decoded amounts and nestedAssetData
+     */
+    decodeMultiAssetDataRecursively(assetData: string): MultiAssetDataWithRecursiveDecoding {
+        const decodedAssetData = assetDataUtils.decodeMultiAssetData(assetData);
+        const decodedNestedAssetData = _.map(decodedAssetData.nestedAssetData as string[], nestedAssetDataElement => {
+            const decodedNestedAssetDataElement = assetDataUtils.decodeAssetDataOrThrow(nestedAssetDataElement);
+            return decodedNestedAssetDataElement.assetProxyId === AssetProxyId.MultiAsset
+                ? assetDataUtils.decodeMultiAssetDataRecursively(nestedAssetDataElement).nestedAssetData
+                : (decodedNestedAssetDataElement as SingleAssetData);
+        });
+        const flattenedDecodedNestedAssetData = _.flattenDeep(decodedNestedAssetData);
+        return {
+            assetProxyId: decodedAssetData.assetProxyId,
+            amounts: decodedAssetData.amounts,
+            nestedAssetData: flattenedDecodedNestedAssetData as SingleAssetData[],
+        };
+    },
+    /**
      * Decode and return the assetProxyId from the assetData
      * @param assetData Hex encoded assetData string to decode
      * @return The assetProxyId
diff --git a/packages/order-utils/src/exchange_transfer_simulator.ts b/packages/order-utils/src/exchange_transfer_simulator.ts
index 06621fd9e..0a948fd1f 100644
--- a/packages/order-utils/src/exchange_transfer_simulator.ts
+++ b/packages/order-utils/src/exchange_transfer_simulator.ts
@@ -108,7 +108,7 @@ export class ExchangeTransferSimulator {
                     const amountsElement = decodedAssetData.amounts[index];
                     const totalAmount = amountInBaseUnits.times(amountsElement);
                     await this.transferFromAsync(
-                        nestedAssetDataElement,
+                        nestedAssetDataElement as string,
                         from,
                         to,
                         totalAmount,
diff --git a/packages/order-utils/src/index.ts b/packages/order-utils/src/index.ts
index e098f23c3..398188433 100644
--- a/packages/order-utils/src/index.ts
+++ b/packages/order-utils/src/index.ts
@@ -38,6 +38,7 @@ export {
     ERC20AssetData,
     ERC721AssetData,
     MultiAssetData,
+    MultiAssetDataWithRecursiveDecoding,
     AssetProxyId,
     SignatureType,
     OrderStateValid,