Dataframe renaming comms listener (#49)

CHANGELOG.md

@@ -5,6 +5,7 @@ All notable changes will be documented here.
 
 ### Changed
 - `STRINGIFY_INDEX_VALUES` is `False` by default (index `.name` will still be a string, but values will keep their original type)
+- Added comms listener for renaming (SQL cell) dataframes.
 
 ## `1.2.0`
 _2022-08-21_

src/dx/comms.py

@@ -1,3 +1,6 @@
+from typing import Optional
+
+import pandas as pd
 import structlog
 from IPython import get_ipython
 from IPython.core.interactiveshell import InteractiveShell
@@ -9,43 +12,89 @@
 
 
 # ref: https://jupyter-notebook.readthedocs.io/en/stable/comms.html#opening-a-comm-from-the-frontend
-def target_func(comm, open_msg):
+def resampler(comm, open_msg):
+    """
+    Datalink resample request.
+    """
+
     @comm.on_msg
     def _recv(msg):
-        handle_comm_msg(msg)
+        # Is separate function to make testing easier.
+        handle_resample_comm(msg)
 
 
-def handle_comm_msg(msg):
-    content = msg.get("content", {})
+def handle_resample_comm(msg):
+    content = msg.get("content")
     if not content:
         return
 
-    data = content.get("data", {})
+    data = content.get("data")
     if not data:
         return
 
-    data = msg["content"]["data"]
-
     if "display_id" in data and "filters" in data:
         # TODO: check for explicit resample value?
         msg = DEXResampleMessage.parse_obj(data)
         handle_resample(msg)
 
 
+def renamer(comm, open_msg):
+    """Rename a SQL cell dataframe."""
+
+    @comm.on_msg
+    def _recv(msg):
+        handle_renaming_comm(msg)
+
+
+def handle_renaming_comm(msg: dict, ipython_shell: Optional[InteractiveShell] = None):
+    """Implementation behind renaming a SQL cell dataframe via comms"""
+    content = msg.get("content")
+    if not content:
+        return
+
+    data = content.get("data")
+    if not data:
+        return
+
+    if "old_name" in data and "new_name" in data:
+
+        if ipython_shell is None:  # noqa
+            # shell will be passed in from test suite, otherwise go with global shell.
+            ipython_shell = get_ipython()
+
+        value_to_rename = ipython_shell.user_ns.get(data["old_name"])
+
+        # Do not rename unless old_name mapped onto exactly a dataframe.
+        #
+        # (Handles case when it maps onto None, indicating that the old name
+        #  hasn't been assigned to at all yet (i.e. user gestured to rename
+        #  SQL cell dataframe name before the SQL cell has even been run the
+        #  first time yet))
+        #
+        if isinstance(value_to_rename, pd.DataFrame):
+            # New name can be empty string, indicating to drop reference to the var.
+            if data["new_name"]:
+                ipython_shell.user_ns[data["new_name"]] = value_to_rename
+
+            # But old name will always be present in message. Delete it now.
+            del ipython_shell.user_ns[data["old_name"]]
+
+
 def register_comm(ipython_shell: InteractiveShell) -> None:
     """
     Registers the comm target function with the IPython kernel.
     """
     from dx.settings import get_settings
 
-    if not get_settings().ENABLE_DATALINK:
-        return
-
     if getattr(ipython_shell, "kernel", None) is None:
         # likely a TerminalInteractiveShell
         return
 
-    ipython_shell.kernel.comm_manager.register_target("datalink", target_func)
+    if get_settings().ENABLE_DATALINK:
+        ipython_shell.kernel.comm_manager.register_target("datalink", resampler)
+
+    if get_settings().ENABLE_RENAMER:
+        ipython_shell.kernel.comm_manager.register_target("rename", renamer)
 
 
 if (ipython := get_ipython()) is not None:

src/dx/settings.py

@@ -68,6 +68,7 @@ class Settings(BaseSettings):
 
     # controls dataframe variable tracking, hashing, and storing in sqlite
     ENABLE_DATALINK: bool = True
+    ENABLE_RENAMER: bool = True
     NUM_PAST_SAMPLES_TRACKED: int = 3
     DB_LOCATION: str = ":memory:"
 

tests/test_comm.py → tests/test_resample_comm.py

@@ -1,11 +1,11 @@
-from dx.comms import handle_comm_msg
+from dx.comms import handle_resample_comm
 from dx.types import DEXResampleMessage
 
 
-def test_handle_comm_msg(mocker):
+def test_handle_resample_comm(mocker):
     """
     Test that `handle_resample` is called with the correctly
-    formatted resample message type if the comm receives
+    formatted resample message type if the comm (`handle_resample_comm`) receives
     the right data structure.
     """
     msg = {
@@ -24,12 +24,12 @@ def test_handle_comm_msg(mocker):
         }
     }
     mock_handle_resample = mocker.patch("dx.comms.handle_resample")
-    handle_comm_msg(msg)
+    handle_resample_comm(msg)
     resample_msg = DEXResampleMessage.parse_obj(msg["content"]["data"])
     mock_handle_resample.assert_called_once_with(resample_msg)
 
 
-def test_handle_comm_msg_skipped(mocker):
+def test_handle_resample_comm_skipped(mocker):
     """
     Test that `handle_resample` is not called with invalid data.
     """
@@ -41,5 +41,5 @@ def test_handle_comm_msg_skipped(mocker):
         }
     }
     mock_handle_resample = mocker.patch("dx.comms.handle_resample")
-    handle_comm_msg(msg)
+    handle_resample_comm(msg)
     mock_handle_resample.assert_not_called()