feat: loader conditionals (#23)

maxb2 · May 25, 2023 · 4bb82de · 4bb82de
1 parent edadf7c
commit 4bb82de
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Showing 4 changed files with 51 additions and 8 deletions.
diff --git a/tests/test_example.py b/tests/test_example.py
@@ -41,9 +41,13 @@ def main(
     (str(HERE.joinpath("config.env")), typer_config.dotenv_conf_callback),
     (
         str(HERE.joinpath("config.ini")),
+        # Have to make one dynamically because of the required INI section
         typer_config.conf_callback_factory(
-            typer_config.loaders.subpath_loader(
-                typer_config.loaders.ini_loader, ["simple_app"]
+            typer_config.loaders.loader_transformer(
+                typer_config.loaders.subpath_loader(
+                    typer_config.loaders.ini_loader, ["simple_app"]
+                ),
+                loader_conditional=lambda param_value: param_value,
             )
         ),
     ),
@@ -55,6 +59,11 @@ def test_simple_example(simple_app, confs):
     conf, callback = confs
     _app = simple_app(callback)
 
+    result = RUNNER.invoke(_app, ["--help"])
+    assert (
+        result.exit_code == 0
+    ), f"Couldn't get to `--help` for {conf}\n\n{result.stdout}"
+
     result = RUNNER.invoke(_app, ["--config", conf])
     assert result.exit_code == 0, f"Loading failed for {conf}\n\n{result.stdout}"
     assert (
@@ -90,6 +99,10 @@ def test_pyproject_example_deprecated(simple_app):
 
     _app = simple_app(pyproject_callback)
 
+    result = RUNNER.invoke(_app, ["--help"])
+
+    assert result.exit_code == 0, f"{result.stdout}"
+
     result = RUNNER.invoke(_app)
 
     assert result.exit_code == 0, f"{result.stdout}"

diff --git a/typer_config/__init__.py b/typer_config/__init__.py
@@ -5,7 +5,13 @@
 from typer import BadParameter, CallbackParam, Context
 
 from .__typing import ConfigLoader, ConfigParameterCallback, TyperParameterValue
-from .loaders import dotenv_loader, json_loader, toml_loader, yaml_loader
+from .loaders import (
+    dotenv_loader,
+    json_loader,
+    toml_loader,
+    yaml_loader,
+    loader_transformer,
+)
 
 
 def conf_callback_factory(loader: ConfigLoader) -> ConfigParameterCallback:
@@ -48,7 +54,9 @@ def _callback(
     return _callback
 
 
-yaml_conf_callback: ConfigParameterCallback = conf_callback_factory(yaml_loader)
+yaml_conf_callback: ConfigParameterCallback = conf_callback_factory(
+    loader_transformer(yaml_loader, loader_conditional=lambda param_value: param_value)
+)
 """YAML typer config parameter callback.
 
 Args:
@@ -64,7 +72,9 @@ def _callback(
     TyperParameterValue: must return back the given parameter
 """
 
-json_conf_callback: ConfigParameterCallback = conf_callback_factory(json_loader)
+json_conf_callback: ConfigParameterCallback = conf_callback_factory(
+    loader_transformer(json_loader, loader_conditional=lambda param_value: param_value)
+)
 """JSON typer config parameter callback.
 
 Args:
@@ -81,7 +91,9 @@ def _callback(
 """
 
 
-toml_conf_callback: ConfigParameterCallback = conf_callback_factory(toml_loader)
+toml_conf_callback: ConfigParameterCallback = conf_callback_factory(
+    loader_transformer(toml_loader, loader_conditional=lambda param_value: param_value)
+)
 """TOML typer config parameter callback.
 
 Args:
@@ -97,7 +109,11 @@ def _callback(
     TyperParameterValue: must return back the given parameter
 """
 
-dotenv_conf_callback: ConfigParameterCallback = conf_callback_factory(dotenv_loader)
+dotenv_conf_callback: ConfigParameterCallback = conf_callback_factory(
+    loader_transformer(
+        dotenv_loader, loader_conditional=lambda param_value: param_value
+    )
+)
 """Dotenv typer config parameter callback.
 
 Args:

diff --git a/typer_config/__typing.py b/typer_config/__typing.py
@@ -38,6 +38,9 @@
 ConfigLoader: TypeAlias = Callable[[TyperParameterValue], ConfigDict]
 """Configuration loader function."""
 
+ConfigLoaderConditional: TypeAlias = Callable[[TyperParameterValue], bool]
+"""Configuration loader conditional function."""
+
 ConfigParameterCallback: TypeAlias = Callable[
     [Context, CallbackParam, TyperParameterValue], TyperParameterValue
 ]

diff --git a/typer_config/loaders.py b/typer_config/loaders.py
@@ -14,6 +14,7 @@
     ConfigDictAccessorPath,
     ConfigDictTransformer,
     ConfigLoader,
+    ConfigLoaderConditional,
     NoArgCallable,
     TyperParameterValue,
     TyperParameterValueTransformer,
@@ -58,6 +59,7 @@
 
 def loader_transformer(
     loader: ConfigLoader,
+    loader_conditional: Optional[ConfigLoaderConditional] = None,
     param_transformer: Optional[TyperParameterValueTransformer] = None,
     config_transformer: Optional[ConfigDictTransformer] = None,
 ) -> ConfigLoader:
@@ -94,6 +96,8 @@ def loader_transformer(
 
     Args:
         loader (ConfigLoader): Loader to transform.
+        loader_condtional (Optional[ConfigLoaderConditional], optional): Function
+            to determine whether to execute loader. Defaults to None (no-op).
         param_transformer (Optional[TyperParameterValueTransformer], optional): Typer
             parameter transformer. Defaults to None (no-op).
         config_transformer (Optional[ConfigDictTransformer], optional): Config
@@ -104,11 +108,18 @@ def loader_transformer(
     """
 
     def _loader(param_value: TyperParameterValue) -> ConfigDict:
+        # Transform input
         if param_transformer is not None:
             param_value = param_transformer(param_value)
 
-        conf: ConfigDict = loader(param_value)
+        # Decide whether to execute loader
+        # NOTE: bad things can happen when `param_value=''`
+        # such as `--help` not working
+        conf: ConfigDict = {}
+        if loader_conditional is None or loader_conditional(param_value):
+            conf = loader(param_value)
 
+        # Transform output
         if config_transformer is not None:
             conf = config_transformer(conf)