Merge pull request #1100 from poanetwork/sa-graphql-transactions-by-address-hash

GraphQL support to get transactions by address

apps/block_scout_web/lib/block_scout_web/etherscan.ex

@@ -925,7 +925,8 @@ defmodule BlockScoutWeb.Etherscan do
 
   @account_txlist_action %{
     name: "txlist",
-    description: "Get transactions by address. Up to a maximum of 10,000 transactions.",
+    description:
+      "Get transactions by address. Up to a maximum of 10,000 transactions. Also available through a GraphQL 'address' query.",
     required_params: [
       %{
         key: "address",

apps/block_scout_web/lib/block_scout_web/resolvers/address.ex

@@ -9,4 +9,11 @@ defmodule BlockScoutWeb.Resolvers.Address do
       result -> {:ok, result}
     end
   end
+
+  def get_by(_, %{hash: hash}, _) do
+    case Chain.hash_to_address(hash) do
+      {:error, :not_found} -> {:error, "Address not found."}
+      {:ok, _} = result -> result
+    end
+  end
 end

apps/block_scout_web/lib/block_scout_web/resolvers/transaction.ex

@@ -1,7 +1,9 @@
 defmodule BlockScoutWeb.Resolvers.Transaction do
   @moduledoc false
 
-  alias Explorer.Chain
+  alias Absinthe.Relay.Connection
+  alias Explorer.{Chain, GraphQL, Repo}
+  alias Explorer.Chain.Address
 
   def get_by(_, %{hash: hash}, _) do
     case Chain.hash_to_transaction(hash) do
@@ -9,4 +11,16 @@ defmodule BlockScoutWeb.Resolvers.Transaction do
       {:error, :not_found} -> {:error, "Transaction hash #{hash} was not found."}
     end
   end
+
+  def get_by(%Address{} = address, args, _) do
+    address
+    |> GraphQL.address_to_transactions_query()
+    |> Connection.from_query(&Repo.all/1, args, options(args))
+  end
+
+  defp options(%{before: _}), do: []
+
+  defp options(%{count: count}), do: [count: count]
+
+  defp options(_), do: []
 end

apps/block_scout_web/lib/block_scout_web/schema.ex

@@ -2,15 +2,44 @@ defmodule BlockScoutWeb.Schema do
   @moduledoc false
 
   use Absinthe.Schema
+  use Absinthe.Relay.Schema, :modern
 
   alias Absinthe.Middleware.Dataloader, as: AbsintheMiddlewareDataloader
   alias Absinthe.Plugin, as: AbsinthePlugin
   alias BlockScoutWeb.Resolvers.{Address, Block, Transaction}
   alias Explorer.Chain
+  alias Explorer.Chain.Transaction, as: ExplorerChainTransaction
 
   import_types(BlockScoutWeb.Schema.Types)
 
+  node interface do
+    resolve_type(fn
+      %ExplorerChainTransaction{}, _ ->
+        :transaction
+
+      _, _ ->
+        nil
+    end)
+  end
+
   query do
+    node field do
+      resolve(fn
+        %{type: :transaction, id: transaction_hash_string}, _ ->
+          {:ok, hash} = Chain.string_to_transaction_hash(transaction_hash_string)
+          Transaction.get_by(%{}, %{hash: hash}, %{})
+
+        _, _ ->
+          {:error, "Unknown node"}
+      end)
+    end
+
+    @desc "Gets an address by hash."
+    field :address, :address do
+      arg(:hash, non_null(:address_hash))
+      resolve(&Address.get_by/3)
+    end
+
     @desc "Gets addresses by address hash."
     field :addresses, list_of(:address) do
       arg(:hashes, non_null(list_of(non_null(:address_hash))))

apps/block_scout_web/lib/block_scout_web/schema/types.ex

@@ -2,12 +2,17 @@ defmodule BlockScoutWeb.Schema.Types do
   @moduledoc false
 
   use Absinthe.Schema.Notation
+  use Absinthe.Relay.Schema.Notation, :modern
 
   import Absinthe.Resolution.Helpers
 
+  alias BlockScoutWeb.Resolvers.Transaction
+
   import_types(Absinthe.Type.Custom)
   import_types(BlockScoutWeb.Schema.Scalars)
 
+  connection(node_type: :transaction)
+
   @desc """
   A stored representation of a Web3 address.
   """
@@ -20,6 +25,19 @@ defmodule BlockScoutWeb.Schema.Types do
     field :smart_contract, :smart_contract do
       resolve(dataloader(:db, :smart_contract))
     end
+
+    connection field(:transactions, node_type: :transaction) do
+      arg(:count, :integer)
+      resolve(&Transaction.get_by/3)
+
+      complexity(fn
+        %{first: first}, child_complexity ->
+          first * child_complexity
+
+        %{last: last}, child_complexity ->
+          last * child_complexity
+      end)
+    end
   end
 
   @desc """
@@ -62,7 +80,7 @@ defmodule BlockScoutWeb.Schema.Types do
   @desc """
   Models a Web3 transaction.
   """
-  object :transaction do
+  node object(:transaction, id_fetcher: &transaction_id_fetcher/2) do
     field(:hash, :full_hash)
     field(:block_number, :integer)
     field(:cumulative_gas_used, :decimal)
@@ -93,4 +111,6 @@ defmodule BlockScoutWeb.Schema.Types do
     field(:token_contract_address_hash, :address_hash)
     field(:transaction_hash, :full_hash)
   end
+
+  def transaction_id_fetcher(%{hash: hash}, _), do: to_string(hash)
 end

apps/block_scout_web/mix.exs

@@ -65,6 +65,8 @@ defmodule BlockScoutWeb.Mixfile do
       {:absinthe_phoenix, "~> 1.4"},
       # Plug support for Absinthe
       {:absinthe_plug, "~> 1.4"},
+      # Absinthe support for the Relay framework
+      {:absinthe_relay, "~> 1.4"},
       {:bypass, "~> 0.8", only: :test},
       {:credo, "0.10.2", only: [:dev, :test], runtime: false},
       # For Absinthe to load data in batches

apps/block_scout_web/test/block_scout_web/schema/query/address_test.exs

@@ -2,12 +2,12 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
   use BlockScoutWeb.ConnCase
 
   describe "address field" do
-    test "with valid argument 'hashes', returns all expected fields", %{conn: conn} do
+    test "with valid argument 'hash', returns all expected fields", %{conn: conn} do
       address = insert(:address, fetched_coin_balance: 100)
 
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!) {
+        address(hash: $hash) {
           hash
           fetched_coin_balance
           fetched_coin_balance_block_number
@@ -16,20 +16,18 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
       }
       """
 
-      variables = %{"hashes" => to_string(address.hash)}
+      variables = %{"hash" => to_string(address.hash)}
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert json_response(conn, 200) == %{
                "data" => %{
-                 "addresses" => [
-                   %{
+                 "address" => %{
                    "hash" => to_string(address.hash),
                    "fetched_coin_balance" => to_string(address.fetched_coin_balance.value),
                    "fetched_coin_balance_block_number" => address.fetched_coin_balance_block_number,
                    "contract_code" => nil
                  }
-                 ]
                }
              }
     end
@@ -38,24 +36,22 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
       address = insert(:contract_address, fetched_coin_balance: 100)
 
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!) {
+        address(hash: $hash) {
           contract_code
         }
       }
       """
 
-      variables = %{"hashes" => to_string(address.hash)}
+      variables = %{"hash" => to_string(address.hash)}
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert json_response(conn, 200) == %{
                "data" => %{
-                 "addresses" => [
-                   %{
+                 "address" => %{
                    "contract_code" => to_string(address.contract_code)
                  }
-                 ]
                }
              }
     end
@@ -65,8 +61,8 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
       smart_contract = insert(:smart_contract, address_hash: address.hash)
 
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!) {
+        address(hash: $hash) {
           fetched_coin_balance
           smart_contract {
             name
@@ -80,14 +76,13 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
       }
       """
 
-      variables = %{"hashes" => to_string(address.hash)}
+      variables = %{"hash" => to_string(address.hash)}
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert json_response(conn, 200) == %{
                "data" => %{
-                 "addresses" => [
-                   %{
+                 "address" => %{
                    "fetched_coin_balance" => to_string(address.fetched_coin_balance.value),
                    "smart_contract" => %{
                      "name" => smart_contract.name,
@@ -98,34 +93,33 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
                      "address_hash" => to_string(address.hash)
                    }
                  }
-                 ]
                }
              }
     end
 
-    test "errors for non-existent address hashes", %{conn: conn} do
+    test "errors for non-existent address hash", %{conn: conn} do
       address = build(:address)
 
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!) {
+        address(hash: $hash) {
           fetched_coin_balance
         }
       }
       """
 
-      variables = %{"hashes" => [to_string(address.hash)]}
+      variables = %{"hash" => to_string(address.hash)}
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert %{"errors" => [error]} = json_response(conn, 200)
-      assert error["message"] =~ ~s(Addresses not found.)
+      assert error["message"] =~ ~s(Address not found.)
     end
 
-    test "errors if argument 'hashes' is missing", %{conn: conn} do
+    test "errors if argument 'hash' is missing", %{conn: conn} do
       query = """
       query {
-        addresses {
+        address {
           fetched_coin_balance
         }
       }
@@ -136,50 +130,423 @@ defmodule BlockScoutWeb.Schema.Query.AddressTest do
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert %{"errors" => [error]} = json_response(conn, 200)
-      assert error["message"] == ~s(In argument "hashes": Expected type "[AddressHash!]!", found null.)
+      assert error["message"] == ~s(In argument "hash": Expected type "AddressHash!", found null.)
     end
 
-    test "errors if argument 'hashes' is not a list of address hashes", %{conn: conn} do
+    test "errors if argument 'hash' is not a valid address hash", %{conn: conn} do
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!) {
+        address(hash: $hash) {
           fetched_coin_balance
         }
       }
       """
 
-      variables = %{"hashes" => ["someInvalidHash"]}
+      variables = %{"hash" => "someInvalidHash"}
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
       assert %{"errors" => [error]} = json_response(conn, 200)
-      assert error["message"] =~ ~s(Argument "hashes" has invalid value)
+      assert error["message"] =~ ~s(Argument "hash" has invalid value)
     end
+  end
+
+  describe "address transactions field" do
+    test "returns all expected transaction fields", %{conn: conn} do
+      address = insert(:address)
 
-    test "correlates complexity to size of 'hashes' argument", %{conn: conn} do
-      # max of 50 addresses with four fields of complexity 1 can be fetched
-      # per query:
-      # 50 * 4 = 200, which is equal to a max complexity of 200
-      hashes = 51 |> build_list(:address) |> Enum.map(&to_string(&1.hash))
+      transaction = insert(:transaction, from_address: address)
 
       query = """
-      query ($hashes: [AddressHash!]!) {
-        addresses(hashes: $hashes) {
+      query ($hash: AddressHash!, $first: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first) {
+            edges {
+              node {
                 hash
-          fetched_coin_balance
-          fetched_coin_balance_block_number
-          contract_code
+                block_number
+                cumulative_gas_used
+                error
+                gas
+                gas_price
+                gas_used
+                index
+                input
+                nonce
+                r
+                s
+                status
+                v
+                value
+                from_address_hash
+                to_address_hash
+                created_contract_address_hash
+              }
+            }
+          }
+        }
+      }
+      """
+
+      variables = %{
+        "hash" => to_string(address.hash),
+        "first" => 1
+      }
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "address" => %{
+                   "transactions" => %{
+                     "edges" => [
+                       %{
+                         "node" => %{
+                           "hash" => to_string(transaction.hash),
+                           "block_number" => transaction.block_number,
+                           "cumulative_gas_used" => nil,
+                           "error" => transaction.error,
+                           "gas" => to_string(transaction.gas),
+                           "gas_price" => to_string(transaction.gas_price.value),
+                           "gas_used" => nil,
+                           "index" => transaction.index,
+                           "input" => to_string(transaction.input),
+                           "nonce" => to_string(transaction.nonce),
+                           "r" => to_string(transaction.r),
+                           "s" => to_string(transaction.s),
+                           "status" => nil,
+                           "v" => transaction.v,
+                           "value" => to_string(transaction.value.value),
+                           "from_address_hash" => to_string(transaction.from_address_hash),
+                           "to_address_hash" => to_string(transaction.to_address_hash),
+                           "created_contract_address_hash" => nil
+                         }
+                       }
+                     ]
+                   }
+                 }
+               }
+             }
+    end
+
+    test "with address with zero transactions", %{conn: conn} do
+      address = insert(:address)
+
+      query = """
+      query ($hash: AddressHash!, $first: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first) {
+            edges {
+              node {
+                hash
+              }
+            }
+          }
+        }
+      }
+      """
+
+      variables = %{
+        "hash" => to_string(address.hash),
+        "first" => 1
+      }
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "address" => %{
+                   "transactions" => %{
+                     "edges" => []
+                   }
+                 }
+               }
+             }
+    end
+
+    test "transactions are ordered by descending block and index", %{conn: conn} do
+      first_block = insert(:block)
+      second_block = insert(:block)
+      third_block = insert(:block)
+
+      address = insert(:address)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(second_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(third_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(first_block)
+
+      query = """
+      query ($hash: AddressHash!, $first: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first) {
+            edges {
+              node {
+                hash
+                block_number
+                index
+              }
+            }
+          }
+        }
+      }
+      """
+
+      variables = %{
+        "hash" => to_string(address.hash),
+        "first" => 3
+      }
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      %{
+        "data" => %{
+          "address" => %{
+            "transactions" => %{
+              "edges" => transactions
+            }
+          }
+        }
+      } = json_response(conn, 200)
+
+      block_number_and_index_order =
+        Enum.map(transactions, fn transaction ->
+          {transaction["node"]["block_number"], transaction["node"]["index"]}
+        end)
+
+      assert block_number_and_index_order == Enum.sort(block_number_and_index_order, &(&1 >= &2))
+      assert length(transactions) == 3
+      assert Enum.all?(transactions, &(&1["node"]["block_number"] == third_block.number))
+    end
+
+    test "complexity correlates to 'first' or 'last' arguments", %{conn: conn} do
+      address = build(:address)
+
+      query = """
+      query ($hash: AddressHash!, $first: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first) {
+            edges {
+              node {
+                hash
+              }
+            }
+          }
+        }
+      }
+      """
+
+      variables = %{
+        "hash" => to_string(address.hash),
+        "first" => 67
+      }
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert %{"errors" => [error1, error2, error3]} = json_response(conn, 200)
+      assert error1["message"] =~ ~s(Field transactions is too complex)
+      assert error2["message"] =~ ~s(Field address is too complex)
+      assert error3["message"] =~ ~s(Operation is too complex)
+    end
+
+    test "with 'last' and 'count' arguments", %{conn: conn} do
+      # "`last: N` must always be acompanied by either a `before:` argument to
+      # the query, or an explicit `count:` option to the `from_query` call.
+      # Otherwise it is impossible to derive the required offset."
+      # https://hexdocs.pm/absinthe_relay/Absinthe.Relay.Connection.html#from_query/4
+      #
+      # This test ensures support of a 'count' argument.
+
+      first_block = insert(:block)
+      second_block = insert(:block)
+      third_block = insert(:block)
+
+      address = insert(:address)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(second_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(third_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(first_block)
+
+      query = """
+      query ($hash: AddressHash!, $last: Int!, $count: Int!) {
+        address(hash: $hash) {
+          transactions(last: $last, count: $count) {
+            edges {
+              node {
+                hash
+                block_number
+              }
+            }
+          }
         }
       }
       """
 
-      variables = %{"hashes" => hashes}
+      variables = %{
+        "hash" => to_string(address.hash),
+        "last" => 3,
+        "count" => 9
+      }
 
       conn = get(conn, "/graphql", query: query, variables: variables)
 
-      assert %{"errors" => [error1, error2]} = json_response(conn, 200)
-      assert error1["message"] =~ ~s(Field addresses is too complex)
-      assert error2["message"] =~ ~s(Operation is too complex)
+      %{
+        "data" => %{
+          "address" => %{
+            "transactions" => %{
+              "edges" => transactions
+            }
+          }
+        }
+      } = json_response(conn, 200)
+
+      assert length(transactions) == 3
+      assert Enum.all?(transactions, &(&1["node"]["block_number"] == first_block.number))
+    end
+
+    test "pagination support with 'first' and 'after' arguments", %{conn: conn} do
+      first_block = insert(:block)
+      second_block = insert(:block)
+      third_block = insert(:block)
+
+      address = insert(:address)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(second_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(third_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(first_block)
+
+      query1 = """
+      query ($hash: AddressHash!, $first: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first) {
+            page_info {
+              has_next_page
+              has_previous_page
+            }
+            edges {
+              node {
+                hash
+                block_number
+              }
+              cursor
+            }
+          }
+        }
+      }
+      """
+
+      variables1 = %{
+        "hash" => to_string(address.hash),
+        "first" => 3
+      }
+
+      conn = get(conn, "/graphql", query: query1, variables: variables1)
+
+      %{"data" => %{"address" => %{"transactions" => page1}}} = json_response(conn, 200)
+
+      assert page1["page_info"] == %{"has_next_page" => true, "has_previous_page" => false}
+      assert Enum.all?(page1["edges"], &(&1["node"]["block_number"] == third_block.number))
+
+      last_cursor_page1 =
+        page1
+        |> Map.get("edges")
+        |> List.last()
+        |> Map.get("cursor")
+
+      query2 = """
+      query ($hash: AddressHash!, $first: Int!, $after: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first, after: $after) {
+            page_info {
+              has_next_page
+              has_previous_page
+            }
+            edges {
+              node {
+                hash
+                block_number
+              }
+              cursor
+            }
+          }
+        }
+      }
+      """
+
+      variables2 = %{
+        "hash" => to_string(address.hash),
+        "first" => 3,
+        "after" => last_cursor_page1
+      }
+
+      conn = get(conn, "/graphql", query: query2, variables: variables2)
+
+      %{"data" => %{"address" => %{"transactions" => page2}}} = json_response(conn, 200)
+
+      assert page2["page_info"] == %{"has_next_page" => true, "has_previous_page" => true}
+      assert Enum.all?(page2["edges"], &(&1["node"]["block_number"] == second_block.number))
+
+      last_cursor_page2 =
+        page2
+        |> Map.get("edges")
+        |> List.last()
+        |> Map.get("cursor")
+
+      query3 = """
+      query ($hash: AddressHash!, $first: Int!, $after: Int!) {
+        address(hash: $hash) {
+          transactions(first: $first, after: $after) {
+            page_info {
+              has_next_page
+              has_previous_page
+            }
+            edges {
+              node {
+                hash
+                block_number
+              }
+              cursor
+            }
+          }
+        }
+      }
+      """
+
+      variables3 = %{
+        "hash" => to_string(address.hash),
+        "first" => 3,
+        "after" => last_cursor_page2
+      }
+
+      conn = get(conn, "/graphql", query: query3, variables: variables3)
+
+      %{"data" => %{"address" => %{"transactions" => page3}}} = json_response(conn, 200)
+
+      assert page3["page_info"] == %{"has_next_page" => false, "has_previous_page" => true}
+      assert Enum.all?(page3["edges"], &(&1["node"]["block_number"] == first_block.number))
     end
   end
 end

apps/block_scout_web/test/block_scout_web/schema/query/addresses_test.exs

@@ -0,0 +1,185 @@
+defmodule BlockScoutWeb.Schema.Query.AddressesTest do
+  use BlockScoutWeb.ConnCase
+
+  describe "addresses field" do
+    test "with valid argument 'hashes', returns all expected fields", %{conn: conn} do
+      address = insert(:address, fetched_coin_balance: 100)
+
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          hash
+          fetched_coin_balance
+          fetched_coin_balance_block_number
+          contract_code
+        }
+      }
+      """
+
+      variables = %{"hashes" => to_string(address.hash)}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "addresses" => [
+                   %{
+                     "hash" => to_string(address.hash),
+                     "fetched_coin_balance" => to_string(address.fetched_coin_balance.value),
+                     "fetched_coin_balance_block_number" => address.fetched_coin_balance_block_number,
+                     "contract_code" => nil
+                   }
+                 ]
+               }
+             }
+    end
+
+    test "with contract address, `contract_code` is serialized as expected", %{conn: conn} do
+      address = insert(:contract_address, fetched_coin_balance: 100)
+
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          contract_code
+        }
+      }
+      """
+
+      variables = %{"hashes" => to_string(address.hash)}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "addresses" => [
+                   %{
+                     "contract_code" => to_string(address.contract_code)
+                   }
+                 ]
+               }
+             }
+    end
+
+    test "smart_contract returns all expected fields", %{conn: conn} do
+      address = insert(:address, fetched_coin_balance: 100)
+      smart_contract = insert(:smart_contract, address_hash: address.hash)
+
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          fetched_coin_balance
+          smart_contract {
+            name
+            compiler_version
+            optimization
+            contract_source_code
+            abi
+            address_hash
+          }
+        }
+      }
+      """
+
+      variables = %{"hashes" => to_string(address.hash)}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "addresses" => [
+                   %{
+                     "fetched_coin_balance" => to_string(address.fetched_coin_balance.value),
+                     "smart_contract" => %{
+                       "name" => smart_contract.name,
+                       "compiler_version" => smart_contract.compiler_version,
+                       "optimization" => smart_contract.optimization,
+                       "contract_source_code" => smart_contract.contract_source_code,
+                       "abi" => Jason.encode!(smart_contract.abi),
+                       "address_hash" => to_string(address.hash)
+                     }
+                   }
+                 ]
+               }
+             }
+    end
+
+    test "errors for non-existent address hashes", %{conn: conn} do
+      address = build(:address)
+
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          fetched_coin_balance
+        }
+      }
+      """
+
+      variables = %{"hashes" => [to_string(address.hash)]}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert %{"errors" => [error]} = json_response(conn, 200)
+      assert error["message"] =~ ~s(Addresses not found.)
+    end
+
+    test "errors if argument 'hashes' is missing", %{conn: conn} do
+      query = """
+      query {
+        addresses {
+          fetched_coin_balance
+        }
+      }
+      """
+
+      variables = %{}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert %{"errors" => [error]} = json_response(conn, 200)
+      assert error["message"] == ~s(In argument "hashes": Expected type "[AddressHash!]!", found null.)
+    end
+
+    test "errors if argument 'hashes' is not a list of address hashes", %{conn: conn} do
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          fetched_coin_balance
+        }
+      }
+      """
+
+      variables = %{"hashes" => ["someInvalidHash"]}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert %{"errors" => [error]} = json_response(conn, 200)
+      assert error["message"] =~ ~s(Argument "hashes" has invalid value)
+    end
+
+    test "correlates complexity to size of 'hashes' argument", %{conn: conn} do
+      # max of 50 addresses with four fields of complexity 1 can be fetched
+      # per query:
+      # 50 * 4 = 200, which is equal to a max complexity of 200
+      hashes = 51 |> build_list(:address) |> Enum.map(&to_string(&1.hash))
+
+      query = """
+      query ($hashes: [AddressHash!]!) {
+        addresses(hashes: $hashes) {
+          hash
+          fetched_coin_balance
+          fetched_coin_balance_block_number
+          contract_code
+        }
+      }
+      """
+
+      variables = %{"hashes" => hashes}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert %{"errors" => [error1, error2]} = json_response(conn, 200)
+      assert error1["message"] =~ ~s(Field addresses is too complex)
+      assert error2["message"] =~ ~s(Operation is too complex)
+    end
+  end
+end

apps/block_scout_web/test/block_scout_web/schema/query/node_test.exs

@@ -0,0 +1,35 @@
+defmodule BlockScoutWeb.Schema.Query.NodeTest do
+  use BlockScoutWeb.ConnCase
+
+  describe "node field" do
+    test "with valid argument 'id' for a transaction", %{conn: conn} do
+      transaction = insert(:transaction)
+
+      query = """
+      query($id: ID!) {
+        node(id: $id) {
+          ... on Transaction {
+            id
+            hash
+          }
+        }
+      }
+      """
+
+      id = Base.encode64("Transaction:#{transaction.hash}")
+
+      variables = %{"id" => id}
+
+      conn = get(conn, "/graphql", query: query, variables: variables)
+
+      assert json_response(conn, 200) == %{
+               "data" => %{
+                 "node" => %{
+                   "id" => id,
+                   "hash" => to_string(transaction.hash)
+                 }
+               }
+             }
+    end
+  end
+end

apps/explorer/lib/explorer/graphql.ex

@@ -0,0 +1,22 @@
+defmodule Explorer.GraphQL do
+  @moduledoc """
+  The GraphQL context.
+  """
+
+  import Ecto.Query,
+    only: [
+      order_by: 3,
+      or_where: 3,
+      where: 3
+    ]
+
+  alias Explorer.Chain.{Address, Hash, Transaction}
+
+  def address_to_transactions_query(%Address{hash: %Hash{byte_count: unquote(Hash.Address.byte_count())} = address_hash}) do
+    Transaction
+    |> order_by([transaction], desc: transaction.block_number, desc: transaction.index)
+    |> where([transaction], transaction.to_address_hash == ^address_hash)
+    |> or_where([transaction], transaction.from_address_hash == ^address_hash)
+    |> or_where([transaction], transaction.created_contract_address_hash == ^address_hash)
+  end
+end

apps/explorer/test/explorer/graphql_test.exs

@@ -0,0 +1,90 @@
+defmodule Explorer.GraphQLTest do
+  use Explorer.DataCase
+
+  import Explorer.Factory
+
+  alias Explorer.{GraphQL, Repo}
+
+  describe "address_to_transactions_query/1" do
+    test "with address hash with zero transactions" do
+      result =
+        :address
+        |> insert()
+        |> GraphQL.address_to_transactions_query()
+        |> Repo.all()
+
+      assert result == []
+    end
+
+    test "with matching 'to_address_hash'" do
+      address = insert(:address)
+      transaction = insert(:transaction, to_address: address)
+      insert(:transaction)
+
+      [found_transaction] =
+        address
+        |> GraphQL.address_to_transactions_query()
+        |> Repo.all()
+
+      assert found_transaction.hash == transaction.hash
+    end
+
+    test "with matching 'from_address_hash'" do
+      address = insert(:address)
+      transaction = insert(:transaction, from_address: address)
+      insert(:transaction)
+
+      [found_transaction] =
+        address
+        |> GraphQL.address_to_transactions_query()
+        |> Repo.all()
+
+      assert found_transaction.hash == transaction.hash
+    end
+
+    test "with matching 'created_contract_address_hash'" do
+      address = insert(:address)
+      transaction = insert(:transaction, created_contract_address: address)
+      insert(:transaction)
+
+      [found_transaction] =
+        address
+        |> GraphQL.address_to_transactions_query()
+        |> Repo.all()
+
+      assert found_transaction.hash == transaction.hash
+    end
+
+    test "orders by descending block and index" do
+      first_block = insert(:block)
+      second_block = insert(:block)
+      third_block = insert(:block)
+
+      address = insert(:address)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(second_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(third_block)
+
+      3
+      |> insert_list(:transaction, from_address: address)
+      |> with_block(first_block)
+
+      found_transactions =
+        address
+        |> GraphQL.address_to_transactions_query()
+        |> Repo.all()
+
+      block_number_and_index_order =
+        Enum.map(found_transactions, fn transaction ->
+          {transaction.block_number, transaction.index}
+        end)
+
+      assert block_number_and_index_order == Enum.sort(block_number_and_index_order, &(&1 >= &2))
+    end
+  end
+end

mix.lock

@@ -4,6 +4,7 @@
   "absinthe": {:hex, :absinthe, "1.4.13", "81eb2ff41f1b62cd6e992955f62c22c042d1079b7936c27f5f7c2c806b8fc436", [:mix], [{:dataloader, "~> 1.0.0", [hex: :dataloader, repo: "hexpm", optional: true]}, {:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: true]}], "hexpm"},
   "absinthe_phoenix": {:hex, :absinthe_phoenix, "1.4.3", "cea34e7ebbc9a252038c1f1164878ee86bcb108905fe462be77efacda15c1e70", [:mix], [{:absinthe, "~> 1.4.0", [hex: :absinthe, repo: "hexpm", optional: false]}, {:absinthe_plug, "~> 1.4.0", [hex: :absinthe_plug, repo: "hexpm", optional: false]}, {:decimal, "~> 1.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:phoenix, "~> 1.2", [hex: :phoenix, repo: "hexpm", optional: false]}, {:phoenix_html, "~> 2.10.5 or ~> 2.11", [hex: :phoenix_html, repo: "hexpm", optional: true]}, {:phoenix_pubsub, "~> 1.0", [hex: :phoenix_pubsub, repo: "hexpm", optional: false]}, {:poison, "~> 2.0 or ~> 3.0", [hex: :poison, repo: "hexpm", optional: false]}], "hexpm"},
   "absinthe_plug": {:hex, :absinthe_plug, "1.4.6", "ac5d2d3d02acf52fda0f151b294017ab06e2ed1c6c15334e06aac82c94e36e08", [:mix], [{:absinthe, "~> 1.4.11", [hex: :absinthe, repo: "hexpm", optional: false]}, {:plug, "~> 1.3.2 or ~> 1.4", [hex: :plug, repo: "hexpm", optional: false]}], "hexpm"},
+  "absinthe_relay": {:hex, :absinthe_relay, "1.4.4", "d0a6d8e71375a6026974d227456c8a73ea8eea7c7b00e698603ab5a96066c333", [:mix], [{:absinthe, "~> 1.4.0", [hex: :absinthe, repo: "hexpm", optional: false]}, {:ecto, "~> 2.0", [hex: :ecto, repo: "hexpm", optional: true]}], "hexpm"},
   "accept": {:hex, :accept, "0.3.3", "548ebb6fb2e8b0d170e75bb6123aea6ceecb0189bb1231eeadf52eac08384a97", [:rebar3], [], "hexpm"},
   "bcrypt_elixir": {:hex, :bcrypt_elixir, "1.1.1", "6b5560e47a02196ce5f0ab3f1d8265db79a23868c137e973b27afef928ed8006", [:make, :mix], [{:elixir_make, "~> 0.4", [hex: :elixir_make, repo: "hexpm", optional: false]}], "hexpm"},
   "benchee": {:hex, :benchee, "0.13.2", "30cd4ff5f593fdd218a9b26f3c24d580274f297d88ad43383afe525b1543b165", [:mix], [{:deep_merge, "~> 0.1", [hex: :deep_merge, repo: "hexpm", optional: false]}], "hexpm"},