Add TokenID to tokentx API endpoint

Since ERC-721 tokens don't have a value, their value is replaced by
their token ID

apps/block_scout_web/lib/block_scout_web/views/api/rpc/address_view.ex

@@ -106,7 +106,7 @@ defmodule BlockScoutWeb.API.RPC.AddressView do
       "from" => to_string(token_transfer.from_address_hash),
       "contractAddress" => to_string(token_transfer.token_contract_address_hash),
       "to" => to_string(token_transfer.to_address_hash),
-      "value" => to_string(token_transfer.amount),
+      "value" => get_token_value(token_transfer),
       "tokenName" => token_transfer.token_name,
       "tokenSymbol" => token_transfer.token_symbol,
       "tokenDecimal" => to_string(token_transfer.token_decimals),
@@ -120,6 +120,14 @@ defmodule BlockScoutWeb.API.RPC.AddressView do
     }
   end
 
+  defp get_token_value(%{token_type: "ERC-721"} = token_transfer) do
+    to_string(token_transfer.token_id)
+  end
+
+  defp get_token_value(token_transfer) do
+    to_string(token_transfer.amount)
+  end
+
   defp prepare_block(block) do
     %{
       "blockNumber" => to_string(block.number),

apps/block_scout_web/test/block_scout_web/controllers/api/rpc/address_controller_test.exs

@@ -1584,6 +1584,41 @@ defmodule BlockScoutWeb.API.RPC.AddressControllerTest do
       assert response["message"] == "No token transfers found"
     end
 
+    test "has correct value for ERC-721", %{conn: conn} do
+      transaction =
+        :transaction
+        |> insert()
+        |> with_block()
+
+      token_address = insert(:contract_address)
+      insert(:token, %{contract_address: token_address, type: "ERC-721"})
+
+      token_transfer =
+        insert(:token_transfer, %{
+          token_contract_address: token_address,
+          token_id: 666,
+          transaction: transaction
+        })
+
+      {:ok, _} = Chain.token_from_address_hash(token_transfer.token_contract_address_hash)
+
+      params = %{
+        "module" => "account",
+        "action" => "tokentx",
+        "address" => to_string(token_transfer.from_address.hash)
+      }
+
+      assert response =
+               %{"result" => [result]} =
+               conn
+               |> get("/api", params)
+               |> json_response(200)
+
+      assert result["value"] == to_string(token_transfer.token_id)
+      assert response["status"] == "1"
+      assert response["message"] == "OK"
+    end
+
     test "returns all the required fields", %{conn: conn} do
       transaction =
         %{block: block} =

apps/explorer/lib/explorer/etherscan.ex

@@ -344,9 +344,11 @@ defmodule Explorer.Etherscan do
             block_number: b.number,
             block_timestamp: b.timestamp,
             confirmations: fragment("? - ?", ^max_block_number, t.block_number),
+            token_id: tt.token_id,
             token_name: tkn.name,
             token_symbol: tkn.symbol,
-            token_decimals: tkn.decimals
+            token_decimals: tkn.decimals,
+            token_type: tkn.type
           })
       )