EnvVariableInject for Fody

EnvVariableInject can be used to inject the values of Environment Variables into fields at build time, this can be useful for injecting build numbers, secret test config values or anything that you might not want to store in your code.

Install from nuget:

Install-Package EnvVariableInject.Fody

If the ModuleWeavers.xml file is not updated automatically then edit to add EnvVariableInject

<Weavers>
  <EnvVariableInject />
</Weavers>

This package is dependent upon Fody

Usage

[BuildTimeEnvironmentVariable("InjectTestString")]
public string TestField = "";

[BuildTimeEnvironmentVariable("InjectTestBool")]
public bool TestBool = false;

[BuildTimeEnvironmentVariable("InjectTestInt")]
public int TestInt = 200;

[BuildTimeEnvironmentVariable("InjectTestDouble")]
public double TestDouble = 99.99;

Replacement will work for fields, static fields and static readonly fields.

The BuildTimeEnvironmentVariableAttribute is added to the project during nuget install.

At build time the weaver will attempt to replace the field with the environment variable specified in the Attribute constructor

Known Issues

The following will not work with the Release Build Configuration

[BuildTimeEnvironmentVariable("TestString")]
public string TestString;

[BuildTimeEnvironmentVariable("TestInt")]
public int TestInt;

This is because the compiler removes the instruction to set the field to null in the constructor. I intend to rectify this issue in the future by injecting the required instructions when they do not exist.

To workaround this just set any value on the field and it will be replaced.