aggregate token transfers

apps/block_scout_web/lib/block_scout_web/templates/transaction/overview.html.eex

@@ -177,7 +177,7 @@
           <div class="card-body card-body-flex-column-space-between">
             <h2 class="card-title balance-card-title"><%= token_type_name(type)%><%= gettext " Token Transfer" %></h2>
             <div class="text-right">
-            <%= for transfer  <- transaction_with_transfers.token_transfers do %>
+            <%= for transfer  <- aggregate_token_transfers(transaction_with_transfers.token_transfers) do %>
 
               <h3 class="address-balance-text">
                   <%= token_transfer_amount(transfer) %>

apps/block_scout_web/lib/block_scout_web/views/tokens/helpers.ex

@@ -4,7 +4,7 @@ defmodule BlockScoutWeb.Tokens.Helpers do
   """
 
   alias BlockScoutWeb.{CurrencyHelpers}
-  alias Explorer.Chain.{Address, Token, TokenTransfer}
+  alias Explorer.Chain.{Address, Token}
 
   @doc """
   Returns the token transfers' amount according to the token's type and decimals.
@@ -16,7 +16,7 @@ defmodule BlockScoutWeb.Tokens.Helpers do
   When the token's type is ERC-721, the function will return a string with the token_id that
   represents the ERC-721 token since this kind of token doesn't have amount and decimals.
   """
-  def token_transfer_amount(%TokenTransfer{token: token, amount: amount, token_id: token_id}) do
+  def token_transfer_amount(%{token: token, amount: amount, token_id: token_id}) do
     do_token_transfer_amount(token, amount, token_id)
   end
 

apps/block_scout_web/lib/block_scout_web/views/transaction_view.ex

@@ -39,6 +39,25 @@ defmodule BlockScoutWeb.TransactionView do
     if type, do: {type, transaction_with_transfers}
   end
 
+  def aggregate_token_transfers(token_transfers) do
+    token_transfers
+    |> Enum.reduce(%{}, fn token_transfer, acc ->
+      new_entry = %{
+        token: token_transfer.token,
+        amount: token_transfer.amount,
+        token_id: token_transfer.token_id
+      }
+
+      existing_entry = Map.get(acc, token_transfer.token.contract_address_hash, %{new_entry | amount: Decimal.new(0)})
+
+      Map.put(acc, token_transfer.token.contract_address_hash, %{
+        new_entry
+        | amount: Decimal.add(new_entry.amount, existing_entry.amount)
+      })
+    end)
+    |> Enum.map(fn {_key, value} -> value end)
+  end
+
   def token_type_name(type) do
     case type do
       :erc20 -> gettext("ERC-20 ")

apps/block_scout_web/test/block_scout_web/views/transaction_view_test.exs

@@ -253,4 +253,20 @@ defmodule BlockScoutWeb.TransactionViewTest do
       assert TransactionView.current_tab_name(logs_path) == "Logs"
     end
   end
+
+  describe "aggregate_token_transfers/1" do
+    test "aggregates token transfers" do
+      transaction =
+        :transaction
+        |> insert()
+        |> with_block()
+
+      token_transfer = insert(:token_transfer, transaction: transaction, amount: Decimal.new(1))
+
+      result = TransactionView.aggregate_token_transfers([token_transfer, token_transfer, token_transfer])
+
+      assert Enum.count(result) == 1
+      assert List.first(result).amount == Decimal.new(3)
+    end
+  end
 end

apps/explorer/test/support/factory.ex

@@ -413,7 +413,7 @@ defmodule Explorer.Factory do
     contract_code = Map.fetch!(contract_code_info(), :bytecode)
 
     token_address = insert(:contract_address, contract_code: contract_code)
-    insert(:token, contract_address: token_address)
+    token = insert(:token, contract_address: token_address)
 
     %TokenTransfer{
       amount: Decimal.new(1),
@@ -422,7 +422,8 @@ defmodule Explorer.Factory do
       to_address: to_address,
       token_contract_address: token_address,
       transaction: log.transaction,
-      log_index: log.index
+      log_index: log.index,
+      token: token
     }
   end