feat: Add set node account id method

CHANGELOG.md

@@ -64,6 +64,7 @@ This changelog is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.
 - Added expiration_time, auto_renew_period, auto_renew_account, fee_schedule_key, kyc_key in `TokenCreateTransaction`, `TokenUpdateTransaction` classes
 - Added comprehensive Google-style docstrings to the `CustomFee` class and its methods in `custom_fee.py`.
 - docs: Add `docs/sdk_developers/project_structure.md` to explain repository layout and import paths.
+- Support selecting specific node account ID(s) for queries and transactions and added `Network._get_node()` with updated execution flow (#362)
 
 ### Changed
 - chore: bumped solo action from 14.0 to 15.0 (#764)

src/hiero_sdk_python/client/network.py

@@ -177,6 +177,21 @@ def _select_node(self) -> _Node:
         self._node_index = (self._node_index + 1) % len(self.nodes)
         self.current_node = self.nodes[self._node_index]
         return self.current_node
+
+    def _get_node(self, account_id: AccountId) -> Optional[_Node]:
+        """
+        Get a node matching the given account ID.
+
+        Args:
+            account_id (AccountId): The account ID of the node to locate.
+
+        Returns:
+            Optional[_Node]: The matching node, or None if not found.
+        """
+        for node in self.nodes:
+            if node._account_id == account_id:
+                return node
+        return None
 
     def get_mirror_address(self) -> str:
         """

src/hiero_sdk_python/executable.py

@@ -1,12 +1,13 @@
 from os import error
 import time
-from typing import Callable, Optional, Any, TYPE_CHECKING
+from typing import Callable, Optional, Any, TYPE_CHECKING, List
 import grpc
 from abc import ABC, abstractmethod
 from enum import IntEnum
 
 from hiero_sdk_python.channels import _Channel
 from hiero_sdk_python.exceptions import MaxAttemptsError
+from hiero_sdk_python.account.account_id import AccountId
 if TYPE_CHECKING:
     from hiero_sdk_python.client.client import Client
 
@@ -75,6 +76,26 @@ def __init__(self):
         self._grpc_deadline = DEFAULT_GRPC_DEADLINE
         self.node_account_id = None
 
+        self.node_account_ids: Optional[List[AccountId]] = None
+        self._used_node_account_id: Optional[AccountId] = None
+
+    def set_node_account_ids(self, node_account_ids: List[AccountId]):
+        """Select node account IDs for sending the request."""
+        self.node_account_ids = node_account_ids
+        return self
+
+    def set_node_account_id(self, node_account_id: AccountId):
+        """Convenience wrapper to set a single node account ID."""
+        return self.set_node_account_ids([node_account_id])
+
+    def _select_node_account_id(self) -> Optional[AccountId]:
+        """Pick the first preferred node if available, otherwise None."""
+        if self.node_account_ids:
+            selected = self.node_account_ids[0]
+            self._used_node_account_id = selected
+            return selected
+        return None
+
     @abstractmethod
     def _should_retry(self, response) -> _ExecutionState:
         """
@@ -176,10 +197,17 @@ def _execute(self, client: "Client"):
             if attempt > 0 and current_backoff < self._max_backoff:
                 current_backoff *= 2
 
-            # Set the node account id to the client's node account id
-            node = client.network.current_node
+            # Select preferred node if provided, fallback to client's default
+            selected = self._select_node_account_id()
+
+            if selected is not None: 
+                node = client.network._get_node(selected)
+            else: 
+                node = client.network.current_node
+
+            #Store for logging and receipts
             self.node_account_id = node._account_id
-  
+
             # Create a channel wrapper from the client's channel
             channel = node._get_channel()
 

src/hiero_sdk_python/query/query.py

@@ -59,6 +59,9 @@ def __init__(self) -> None:
         self.node_index: int = 0
         self.payment_amount: Optional[Hbar] = None
 
+        self.node_account_ids: Optional[List[AccountId]] = None
+        self._used_node_account_id: Optional[AccountId] = None
+
     def _get_query_response(self, response: Any) -> query_pb2.Query:
         """
         Extracts the query-specific response object from the full response.
@@ -379,3 +382,4 @@ def _is_payment_required(self) -> bool:
             bool: True if payment is required, False otherwise
         """
         return True
+

src/hiero_sdk_python/transaction/transaction.py

@@ -1,5 +1,5 @@
 import hashlib
-from typing import Optional
+from typing import List, Optional
 
 from typing import TYPE_CHECKING
 
@@ -59,7 +59,7 @@ def __init__(self) -> None:
         # and ensures that the correct signatures are used when submitting transactions
         self._signature_map: dict[bytes, basic_types_pb2.SignatureMap] = {}
         self._default_transaction_fee = 2_000_000
-        self.operator_account_id = None  
+        self.operator_account_id = None
 
     def _make_request(self):
         """

tests/unit/test_query_nodes.py

@@ -0,0 +1,31 @@
+import pytest
+from hiero_sdk_python.query.query import Query
+from hiero_sdk_python.account.account_id import AccountId
+
+def test_set_single_node_account_id():
+    q = Query()
+    node = AccountId(0, 0, 3)
+
+    q.set_node_account_id(node)
+
+    assert q.node_account_ids == [node]
+    assert q._used_node_account_id is None  # not selected until execution
+
+def test_set_multiple_node_account_ids():
+    q = Query()
+    nodes = [AccountId(0, 0, 3), AccountId(0, 0, 4)]
+
+    q.set_node_account_ids(nodes)
+
+    assert q.node_account_ids == nodes
+    assert q._used_node_account_id is None
+
+def test_select_node_account_id():
+    q = Query()
+    nodes = [AccountId(0, 0, 3), AccountId(0, 0, 4)]
+    q.set_node_account_ids(nodes)
+
+    selected = q._select_node_account_id()
+
+    assert selected == nodes[0]
+    assert q._used_node_account_id == nodes[0]

tests/unit/test_transaction_nodes.py

@@ -0,0 +1,52 @@
+import pytest
+from hiero_sdk_python.transaction.transaction import Transaction
+from hiero_sdk_python.account.account_id import AccountId
+
+
+class DummyTransaction(Transaction):
+    """
+    Minimal subclass of Transaction for testing.
+    Transaction is abstract (requires build methods), so we stub them out.
+    """
+    def __init__(self):
+        super().__init__()
+
+    def build_base_transaction_body(self):
+        return None  # stub
+
+    def _make_request(self):
+        return None  # stub
+
+    def _get_method(self):
+        return None  # stub
+
+
+def test_set_single_node_account_id():
+    txn = DummyTransaction()
+    node = AccountId(0, 0, 3)
+
+    txn.set_node_account_id(node)
+
+    assert txn.node_account_ids == [node]
+    assert txn._used_node_account_id is None
+
+
+def test_set_multiple_node_account_ids():
+    txn = DummyTransaction()
+    nodes = [AccountId(0, 0, 3), AccountId(0, 0, 4)]
+
+    txn.set_node_account_ids(nodes)
+
+    assert txn.node_account_ids == nodes
+    assert txn._used_node_account_id is None
+
+
+def test_select_node_account_id():
+    txn = DummyTransaction()
+    nodes = [AccountId(0, 0, 3), AccountId(0, 0, 4)]
+    txn.set_node_account_ids(nodes)
+
+    selected = txn._select_node_account_id()
+
+    assert selected == nodes[0]
+    assert txn._used_node_account_id == nodes[0]