How to add //<auto-generated /> automatically to generated files? More specifically migrations

Question

So i have my migrations folder from ef core right? But my IDE style code throws a bunch of errors in the generated files, so i need to manually insert the // comment, so everything is ignored. Is there any way, that whenever a new migration is added to add this automatically?

Answer 1

You can do this by creating your own custom CSharpDbContextGenerator and CSharpEntityTypeGenerator classes. For example:

public class MyContextTypeGenerator : CSharpDbContextGenerator
{
    public MyContextTypeGenerator(
        IProviderConfigurationCodeGenerator providerConfigurationCodeGenerator,
        IAnnotationCodeGenerator annotationCodeGenerator,
        ICSharpHelper cSharpHelper) : base(providerConfigurationCodeGenerator, annotationCodeGenerator, cSharpHelper)
    {
    }

    public override string WriteCode(
        IModel model,
        string contextName,
        string connectionString,
        string contextNamespace,
        string modelNamespace,
        bool useDataAnnotations,
        bool useNullableReferenceTypes,
        bool suppressConnectionStringWarning,
        bool suppressOnConfiguring)
    {
        var builder = new IndentedStringBuilder();

        // Add your own code to the start
        builder.AppendLine("// <auto-generated>");

        // Add the default code be generated
        builder.Append(base.WriteCode(model, contextName, connectionString, contextNamespace, modelNamespace, useDataAnnotations, useNullableReferenceTypes, suppressConnectionStringWarning, suppressOnConfiguring));

        return builder.ToString();
    }
}

And for the entities:

public class MyEntityTypeGenerator : CSharpEntityTypeGenerator
{
    public MyEntityTypeGenerator(IAnnotationCodeGenerator annotationCodeGenerator, ICSharpHelper cSharpUtilities)
        : base(annotationCodeGenerator, cSharpUtilities)
    {
    }


    public override string WriteCode(IEntityType entityType, string @namespace, bool useDataAnnotations, bool useNullableReferenceTypes)
    {
        var builder = new StringBuilder();

        builder.AppendLine("// <auto-generated>");

        builder.Append(base.WriteCode(entityType, @namespace, useDataAnnotations, useNullableReferenceTypes));

        return builder.ToString();

    }
}

Then you need to ensure the types gets used by EF, so add this class too:

public class MyDesignTimeServices : IDesignTimeServices
{
    public void ConfigureDesignTimeServices(IServiceCollection serviceCollection)
    {
        serviceCollection.AddSingleton<ICSharpDbContextGenerator, MyContextTypeGenerator>();
        serviceCollection.AddSingleton<ICSharpEntityTypeGenerator, MyEntityTypeGenerator>();

    }
}

Note 1: You probably also need to add the Microsoft.EntityFrameworkCore.Design Nuget package.

Note 2: This will give you a warning about using EF Core internal classes which you can disable with:

#pragma warning disable EF1001