ConfigWrapper.Json 1.5.0

ConfigWrapper

A simple configuration wrapper to abstract config sources and offer sensible defaults.

Getting Started

Available on Nuget

Prerequisites

.net 4.0 +

Use

Interfaces

The IConfigWrapper provides the contract for reading config values.
The IWritableConfigWrapper provides the contract for reading and writing values.

Simple values

In this example, we return 1000 if there is no configured value in the app.config or web.config file.

IConfigWrapper = new AppSettingsConfigWrapper();
var sleepMs = configWrapper.Get<int>("sleep-time-in-ms", 1000);

Arrays

In this example, we return an array of strings from the Windows registry, delimited by , or |.
If we have no values for the specified key, we get the array ["pork", "beans"]

IConfigWrapper = new WindowsRegistryConfigWrapper();
var items = configWrapper.Get<string[]>("HKCU/topkey/subkey/valuekey", new [] {"pork", "beans"}, []{',''|'});

Exceptions

By default, the neither the AppSettingsConfigWrapper nor the WindowsRegistryConfigWrapper throws an exception if a config has a value of the wrong type. If it cannot cast, it returns the default.

Example: for a config entry

<appSettings>
	<add key="sleep-time-in-ms" value="chicken sandwich"/>
</appSettings>

and the code

IConfigWrapper = new AppSettingsConfigWrapper();
var sleepMs = configWrapper.Get<int>("sleep-time-in-ms", 1000);
// sleepMs = 1000

We try to cast the value "chicken sandwich" to an int. This fails, so we return 1000.

To throw an exception, pass in true for errorOnWrongType.

IConfigWrapper = new AppSettingsConfigWrapper();
var sleepMs = configWrapper.Get<int>("sleep-time-in-ms", 1000, true);
//throws an Exception

Required config values

If you do not pass in a default, it will error on missing values or values that cannot be cast.

IConfigWrapper = new AppSettingsConfigWrapper();
var sleepMs = configWrapper.Get<int>("this-key-is-not-in-the-config");
//  throws an exception

Sources

Each config wrapper loads from a different source.

AppSettingsConfigWrapper

Loads from the current application's app.config or web.config

<appSettings>
	<add key="sleep-time-in-ms" value="5000"/>
</appSettings>

IConfigWrapper configWrapper = new AppSettingsConfigWrapper();
var sleepMs = configWrapper.Get<int>("sleep-time-in-ms", 1000);
// sleepMs = 5000

WindowsRegistryConfigWrapper

Loads from the Windows registry, defining a root key for my application.

IWritableConfigWrapper = new WindowsRegistryConfigWrapper("HKLM/Software/MyApplication/");
configWrapper.Set<int>("MyKey", 5000); 
var sleepMs = configWrapper.Get<int>("MyKey", 5000);
// sleepMs = 5000

You can also give it fully-qualified key names as well, but it will use the canonnical name of the root key: e.g. HKCU becomes HKEY_CURRENT_USER.

IWritableConfigWrapper = new WindowsRegistryConfigWrapper("HKLM/Software/MyApplication/");
configWrapper.Set<int>("HKEY_LOCAL_MACHINE/Software/MyApplication/MyKey", 5000); 
var sleepMs = configWrapper.Get<int>("HKEY_LOCAL_MACHINE/Software/MyApplication/MyKey", 5000);
// sleepMs = 5000

WARNING

While the WindowsRegistryConfigWrapper will not modify root level keys e.g. "`", it should be used with care. It is a sharp knife, be careful.

IniConfigWrapper

Supports ini files with values like

myvalue=foo

JSONConfigWrapper

The json wrapper is in a separate nuget package: ConfigWrapper.Json. It has a dependency on Newtonsoft, so it is distributed separately from ConfigWrapper.

IConfigWrapper configWrapper = new JsonConfigWrapper("../data.json");
var sleepMs = configWrapper.Get<int>("sleep-time-in-ms", 5000);
// sleepMs = 5000

InMemoryConfigWrapper

The in memory wrapper is useful for unit test scenarios or where we want to hold onto a config temporarily.

Authors

See the list of contributors who participated in this project.

License

This project is licensed under the MIT License

Acknowledgments

• Hat tip to the teams at Spotlite (RallyHealth), Guaranteed Rate, GrubHub, and Endava for their feedback.