feat: @metric_input as a standardized way to input --metric values

examples/metricq_get_history.py

@@ -37,6 +37,7 @@
 
 import metricq
 from metricq.cli import metricq_command
+from metricq.cli.params import metric_input
 
 logger = metricq.get_logger()
 
@@ -100,7 +101,7 @@ async def aget_history(
 
 
 @metricq_command(default_token="history-py-dummy")
-@click.option("--metric", default=None)
+@metric_input()
 @click.option("--list-metrics", is_flag=True)
 @click.option("--list-metadata", is_flag=True)
 @click_log.simple_verbosity_option(logger)  # type: ignore

examples/metricq_pandas.py

@@ -35,7 +35,7 @@
 import click_log  # type: ignore
 
 import metricq
-from metricq.cli import metricq_command
+from metricq.cli import metric_input, metricq_command
 from metricq.pandas import PandasHistoryClient
 
 logger = metricq.get_logger()
@@ -83,7 +83,7 @@ async def aget_history(server: str, token: str, metric: str) -> None:
 
 
 @metricq_command(default_token="history-py-dummy")
-@click.option("--metric", default="example.quantity")
+@metric_input(default="example.quantity")
 @click_log.simple_verbosity_option(logger)  # type: ignore
 def get_history(server: str, token: str, metric: str) -> None:
     asyncio.run(aget_history(server, token, metric))

metricq/cli/__init__.py

@@ -1,11 +1,12 @@
-from .command import metricq_command
 from .params import (
     ChoiceParam,
     CommandLineChoice,
     DurationParam,
     TemplateStringParam,
     TimestampParam,
+    metric_input,
 )
+from .wrapper import metricq_command
 
 __all__ = [
     "ChoiceParam",
@@ -14,4 +15,5 @@
     "TemplateStringParam",
     "TimestampParam",
     "metricq_command",
+    "metric_input",
 ]

metricq/cli/params.py

@@ -3,12 +3,12 @@
 from getpass import getuser
 from socket import gethostname
 from string import Template
-from typing import Any, Generic, List, Optional, Type, TypeVar, Union, cast
+from typing import Any, Generic, List, Optional, Type, TypeVar, Union, cast, Callable
 
-import click
 from click import Context, Parameter, ParamType, option
 
 from ..timeseries import Timedelta, Timestamp
+from .types import FC
 
 _C = TypeVar("_C", covariant=True)
 
@@ -169,3 +169,28 @@ def convert(
         if not isinstance(value, str):
             raise TypeError("expected a string type for TemplateStringParam")
         return Template(value).safe_substitute(self.mapping)
+
+
+class MetricInputParam(ParamType):
+    pattern = re.compile(r"([a-zA-Z][a-zA-Z0-9_]+\.)+[a-zA-Z][a-zA-Z0-9_]+")
+
+    def convert(
+        self, value: Any, param: Optional[Parameter], ctx: Optional[Context]
+    ) -> str:
+        if not isinstance(value, str):
+            raise TypeError("expected a string type for the metric input")
+        if not self.pattern.match(value):
+            raise ValueError(f"Invalid metric format: '{value}'.")
+        return value
+
+
+def metric_input(default: Optional[str] = None) -> Callable[[FC], FC]:
+    return option(
+        "--metric",
+        type=MetricInputParam(),
+        metavar="METRIC",
+        show_default=True,
+        required=default is None,
+        default=default,
+        help="Use the -–metric parameter to specify which metric the program should use",
+    )

metricq/cli/types.py

@@ -0,0 +1,5 @@
+from typing import Any, Callable, TypeVar, Union
+
+import click
+
+FC = TypeVar("FC", bound=Union[Callable[..., Any], click.Command])

metricq/cli/command.py → metricq/cli/wrapper.py

@@ -7,7 +7,8 @@
 from dotenv import find_dotenv, load_dotenv
 
 from .. import get_logger
-from .params import FC, TemplateStringParam
+from .params import TemplateStringParam
+from .types import FC
 
 # We do not interpolate (i.e. replace ${VAR} with corresponding environment variables).
 # That is because we want to be able to interpolate ourselves for metrics and tokens