Add lazy commands (#51)

* Add lazy commands

* Add Lazy group

Author: lsbardel

.dev/lint

@@ -1,14 +1,18 @@
 #!/usr/bin/env bash
 set -e
 
+ISORT_ARGS="-c"
 BLACK_ARG="--check"
 RUFF_ARG=""
 
 if [ "$1" = "fix" ] ; then
+    ISORT_ARGS=""
     BLACK_ARG=""
     RUFF_ARG="--fix"
 fi
 
+echo isort
+isort fluid tests examples ${ISORT_ARGS}
 echo "run black"
 black fluid tests examples ${BLACK_ARG}
 echo "run ruff"

examples/__main__.py

@@ -0,0 +1,12 @@
+import dotenv
+
+dotenv.load_dotenv()
+
+from fluid.scheduler.cli import TaskManagerCLI  # isort:skip    # noqa: E402
+
+task_manager_cli = TaskManagerCLI(
+    "examples.tasks:task_app", lazy_subcommands={"db": "examples.db.cli:cli"}
+)
+
+
+task_manager_cli()

examples/db/cli.py

@@ -0,0 +1,3 @@
+from examples.db import get_db
+
+cli = get_db().cli()

examples/db/migrations/versions/1f91ed2b2f26_initial.py

@@ -1,7 +1,7 @@
 """initial
 
 Revision ID: 1f91ed2b2f26
-Revises: 
+Revises:
 Create Date: 2024-08-18 10:19:38.372777
 
 """

examples/main_db.py

@@ -1,3 +1,3 @@
 """Reusable server side python modules"""
 
-__version__ = "1.2.2"
+__version__ = "1.2.3"

examples/main_tasks.py

@@ -10,6 +10,7 @@
 from uvicorn.importer import import_from_string
 
 from fluid.utils import log
+from fluid.utils.lazy import LazyGroup
 
 if TYPE_CHECKING:
     from .consumer import TaskManager
@@ -19,8 +20,12 @@
 TaskManagerApp = FastAPI | Callable[..., Any] | str
 
 
-class TaskManagerCLI(click.Group):
-    def __init__(self, task_manager_app: TaskManagerApp, **kwargs: Any):
+class TaskManagerCLI(LazyGroup):
+    def __init__(
+        self,
+        task_manager_app: TaskManagerApp,
+        **kwargs: Any,
+    ):
         kwargs.setdefault("commands", DEFAULT_COMMANDS)
         super().__init__(**kwargs)
         self.task_manager_app = task_manager_app

fluid/__init__.py

@@ -1,5 +1,4 @@
-"""Originally from https://github.com/coleifer/huey
-"""
+"""Originally from https://github.com/coleifer/huey"""
 
 import re
 from abc import ABC, abstractmethod

fluid/scheduler/cli.py

@@ -0,0 +1,41 @@
+from importlib import import_module
+from typing import Any
+
+import click
+
+
+class LazyGroup(click.Group):
+    def __init__(
+        self,
+        *,
+        lazy_subcommands: dict[str, str] | None = None,
+        **kwargs: Any,
+    ):
+        super().__init__(**kwargs)
+        self.lazy_subcommands = lazy_subcommands or {}
+
+    def list_commands(self, ctx: click.Context) -> list[str]:
+        commands = super().list_commands(ctx)
+        commands.extend(self.lazy_subcommands)
+        return sorted(commands)
+
+    def get_command(self, ctx: click.Context, cmd_name: str) -> click.Command | None:
+        if cmd_name in self.lazy_subcommands:
+            return self._lazy_load(cmd_name)
+        return super().get_command(ctx, cmd_name)
+
+    def _lazy_load(self, cmd_name: str) -> click.Command:
+        # lazily loading a command, first get the module name and attribute name
+        import_path = self.lazy_subcommands[cmd_name]
+        modname, cmd_object_name = import_path.rsplit(":", 1)
+        # do the import
+        mod = import_module(modname)
+        # get the Command object from that module
+        cmd_object = getattr(mod, cmd_object_name)
+        # check the result to make debugging easier
+        if not isinstance(cmd_object, click.Command):
+            raise ValueError(
+                f"Lazy loading of {import_path} failed by returning "
+                "a non-command object"
+            )
+        return cmd_object