How to configure startup.cs based on solution configuration and not environment variable?

问题

One way of configuring startup.cs is to check the environment based on an environmental variable, and run the appropriate code within the Configure method:

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    if (env.IsDevelopment())
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
        // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
        app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    //app.UseCookiePolicy();

    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");
    });
}

For the app I'm working on, I can't guarantee that I will have access to clients' machines to add the ASPNETCORE_ENVIRONMENT environmental variable to make sure they're routed to the correct exception page. But I also don't want to keep having to remember to comment out certain code when I'm about to publish the project.

How can I instead get the project's configuration name to determine what code I want run?:

Here's some pseudocode of what I'd like to accomplish:

// This method gets called by the runtime. Use this method to configure the HTTP request pipeline.
public void Configure(IApplicationBuilder app, IHostingEnvironment env)
{
    //I get the configuration name (could be "Debug", "Development", or "Release)
    //from the list in the photo
    string configurationName = GetConfigurationName();

    //I compare the name to determine what error page to show
    if (configurationName == "Debug" || configurationName == "Development")
    {
        app.UseDeveloperExceptionPage();
    }
    else
    {
        app.UseExceptionHandler("/Home/Error");
        // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
        app.UseHsts();
    }

    app.UseHttpsRedirection();
    app.UseStaticFiles();
    //app.UseCookiePolicy();

    app.UseMvc(routes =>
    {
        routes.MapRoute(
            name: "default",
            template: "{controller=Home}/{action=Index}/{id?}");
    });
}

回答1:

If you can't make it work with the environment, you could use a preprocessor directive. When deploying your code to production, make sure you are compiling with RELEASE as solution configuration:

#if DEBUG
    app.UseDeveloperExceptionPage();
#elif RELEASE
    app.UseExceptionHandler("/Home/Error");
    // The default HSTS value is 30 days. You may want to change this for production scenarios, see https://aka.ms/aspnetcore-hsts.
    app.UseHsts();
#endif

You can find some nice examples here:

来源：https://stackoverflow.com/questions/62174785/how-to-configure-startup-cs-based-on-solution-configuration-and-not-environment