Ignore the burn_address for ERC-721 in the query

apps/explorer/lib/explorer/chain.ex

@@ -938,7 +938,7 @@ defmodule Explorer.Chain do
   def stream_unfetched_token_balances(initial, reducer) when is_function(reducer, 2) do
     Repo.transaction(
       fn ->
-        query = from(tb in TokenBalance, where: is_nil(tb.value_fetched_at))
+        query = TokenBalance.unfetched_token_balances()
 
         query
         |> Repo.stream(timeout: :infinity)

apps/explorer/lib/explorer/chain/address/token_balance.ex

@@ -129,4 +129,24 @@ defmodule Explorer.Chain.Address.TokenBalance do
       tb.value < ^value or (tb.value == ^value and tb.address_hash < ^address_hash)
     )
   end
+
+  {:ok, burn_address_hash} = Chain.string_to_address_hash("0x0000000000000000000000000000000000000000")
+  @burn_address_hash burn_address_hash
+
+  @doc """
+  Builds an `Ecto.Query` to fetch the unfetched token balances.
+
+  Unfetched token balances are the ones that have the column `value_fetched_at` nil. This query also
+  ignores the burn_address for tokens ERC-721 since the most tokens ERC-721 don't allow get the
+  balance for burn_address.
+  """
+  def unfetched_token_balances do
+    from(
+      tb in TokenBalance,
+      join: t in Token,
+      on: tb.token_contract_address_hash == t.contract_address_hash,
+      where: is_nil(tb.value_fetched_at),
+      where: (tb.address_hash != ^@burn_address_hash and t.type != "ERC-721") or t.type == "ERC-20"
+    )
+  end
 end

apps/explorer/test/explorer/chain/address/token_balance_test.ex

@@ -0,0 +1,79 @@
+defmodule Explorer.Chain.Address.TokenBalanceTest do
+  use Explorer.DataCase
+
+  alias Explorer.Repo
+  alias Explorer.Chain.Address.TokenBalance
+
+  describe "unfetched_token_balances/0" do
+    test "returns only the token balances that have value_fetched_at nil" do
+      address = insert(:address, hash: "0xc45e4830dff873cf8b70de2b194d0ddd06ef651e")
+      token_balance = insert(:token_balance, value_fetched_at: nil, address: address)
+      insert(:token_balance)
+
+      result =
+        TokenBalance.unfetched_token_balances()
+        |> Repo.all()
+        |> List.first()
+
+      assert result.block_number == token_balance.block_number
+    end
+
+    test "does not ignore token balance when the address isn't the burn address with Token ERC-20" do
+      address = insert(:address, hash: "0xc45e4830dff873cf8b70de2b194d0ddd06ef651e")
+      token = insert(:token, type: "ERC-20")
+
+      token_balance =
+        insert(
+          :token_balance,
+          value_fetched_at: nil,
+          address: address,
+          token_contract_address_hash: token.contract_address_hash
+        )
+
+      result =
+        TokenBalance.unfetched_token_balances()
+        |> Repo.all()
+        |> List.first()
+
+      assert result.block_number == token_balance.block_number
+    end
+
+    test "ignores the burn_address when the token type is ERC-721" do
+      burn_address = insert(:address, hash: "0x0000000000000000000000000000000000000000")
+      token = insert(:token, type: "ERC-721")
+
+      insert(
+        :token_balance,
+        address: burn_address,
+        token_contract_address_hash: token.contract_address_hash,
+        value_fetched_at: nil
+      )
+
+      result =
+        TokenBalance.unfetched_token_balances()
+        |> Repo.all()
+
+      assert result == []
+    end
+
+    test "does not ignore the burn_address when the token type is ERC-20" do
+      burn_address = insert(:address, hash: "0x0000000000000000000000000000000000000000")
+      token = insert(:token, type: "ERC-20")
+
+      token_balance =
+        insert(
+          :token_balance,
+          address: burn_address,
+          token_contract_address_hash: token.contract_address_hash,
+          value_fetched_at: nil
+        )
+
+      result =
+        TokenBalance.unfetched_token_balances()
+        |> Repo.all()
+        |> List.first()
+
+      assert result.block_number == token_balance.block_number
+    end
+  end
+end

apps/explorer/test/explorer/chain_test.exs

@@ -2326,8 +2326,9 @@ defmodule Explorer.ChainTest do
   end
 
   describe "stream_unfetched_token_balances/2" do
-    test "returns only the token balances that have value_fetched_at nil" do
-      token_balance = insert(:token_balance, value_fetched_at: nil)
+    test "executes the given reducer with the query result" do
+      address = insert(:address, hash: "0xc45e4830dff873cf8b70de2b194d0ddd06ef651e")
+      token_balance = insert(:token_balance, value_fetched_at: nil, address: address)
       insert(:token_balance)
 
       assert Chain.stream_unfetched_token_balances([], &[&1.block_number | &2]) == {:ok, [token_balance.block_number]}