Скачать или смотреть How to Pass Preprocessor Directives to MSBuild via dotnet publish

Learn how to effectively pass preprocessor directives to MSBuild while using `dotnet publish`. This guide covers implementing conditional builds for ASP.NET Core projects, specifically with Docker integrations.
---
This video is based on the question https://stackoverflow.com/q/71818999/ asked by the user 'Eternal21' ( https://stackoverflow.com/u/1288473/ ) and on the answer https://stackoverflow.com/a/71878982/ provided by the user 'Eternal21' ( https://stackoverflow.com/u/1288473/ ) at 'Stack Overflow' website. Thanks to these great users and Stackexchange community for their contributions.

Visit these links for original content and any more details, such as alternate solutions, latest updates/developments on topic, comments, revision history etc. For example, the original title of the Question was: How to pass preprocessor directive to MSBuild via dotnet publish

Also, Content (except music) licensed under CC BY-SA https://meta.stackexchange.com/help/l...
The original Question post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license, and the original Answer post is licensed under the 'CC BY-SA 4.0' ( https://creativecommons.org/licenses/... ) license.

If anything seems off to you, please feel free to write me at vlogize [AT] gmail [DOT] com.
---
How to Pass Preprocessor Directives to MSBuild via dotnet publish

When building applications, especially in environments like ASP.NET Core, the need for flexibility is paramount. One common challenge developers face is the ability to conditionally compile parts of their code based on specific scenarios, such as when preparing for a Docker deployment. In this guide, we will explore how to pass preprocessor directives to MSBuild using the dotnet publish command, enabling conditional builds that cater to different hosting environments.

The Problem

Imagine you have a robust ASP.NET Core application that includes a SPA (Single Page Application). In your case, you are migrating your Web API to Docker and want to manage builds such that the SPA can be conditionally included or excluded. This can be particularly useful when you’re not ready to fully separate the two components but still wish to streamline your builds.

Your main questions are:

How can you pass a parameter from the build command line to the MSBuild engine to include or exclude the PublishAngular target in your .csproj file?

Is it possible to reuse the DOCKER_BUILD preprocessor directive to accomplish this goal?

Understanding the Solution

To address your challenge, we will leverage the DefineConstants parameter in MSBuild, which allows us to include or exclude certain code sections based on preprocessor directives. Let's break this down step by step:

Step 1: Modify the Build Command Line

To notify MSBuild that you want to conditionally compile based on whether you are building for Docker, use the following command:

[[See Video to Reveal this Text or Code Snippet]]

Step 2: Update Your csproj Target Condition

Next, you will want to modify the PublishAngular target in your .csproj file to respect the DOCKER_BUILD preprocessor directive. Here’s how you can set it up:

[[See Video to Reveal this Text or Code Snippet]]

This means that the PublishAngular target will only execute if the DOCKER_BUILD directive is not present in the DefineConstants variable.

Step 3: Application of the Directive in C# Files

The modification you applied also works within your C# code. Here’s a quick reminder of how you would handle your conditional logic based on the directive:

[[See Video to Reveal this Text or Code Snippet]]

Why This Works

The DefineConstants property is a special parameter that MSBuild understands. By appending it to the build command line, you inform the MSBuild system about certain compilation flags that apply to your project. The conditional logic in your .csproj file uses this to check whether to execute the relevant target based on the presence of the DOCKER_BUILD directive.

Conclusion

By implementing the strategies outlined above, you can efficiently manage conditional builds for your ASP.NET Core applications during Docker migrations. The ability to use the DefineConstants parameter and adjust target conditions in your project files will enhance your workflow and make your development process smoother.

Remember, as you continue to work on separating the SPA from your Web API, these adjustments will provide the flexibility you need to streamline your build process while ensuring your application remains robust and adaptable. Happy coding!