booking-microservices/src/BuildingBlocks/EFCore/Extensions.cs

using System.Linq.Expressions;
using BuildingBlocks.Core.Model;
using BuildingBlocks.Web;
using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Hosting;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Query;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Hosting;

namespace BuildingBlocks.EFCore;

using Ardalis.GuardClauses;
using Humanizer;
using Microsoft.EntityFrameworkCore.Metadata;

public static class Extensions
{
    public static IServiceCollection AddCustomDbContext<TContext>(
        this IServiceCollection services)
        where TContext : DbContext, IDbContext
    {
        AppContext.SetSwitch("Npgsql.EnableLegacyTimestampBehavior", true);

        services.AddValidateOptions<PostgresOptions>();

        services.AddDbContext<TContext>((sp, options) =>
        {
            var postgresOptions = sp.GetRequiredService<PostgresOptions>();

            Guard.Against.Null(options, nameof(postgresOptions));

            options.UseNpgsql(postgresOptions?.ConnectionString,
                    dbOptions =>
                    {
                        dbOptions.MigrationsAssembly(typeof(TContext).Assembly.GetName().Name);
                        //ref: https://learn.microsoft.com/en-us/ef/core/miscellaneous/connection-resiliency
                        // dbOptions.EnableRetryOnFailure(3, TimeSpan.FromSeconds(1), null);
                    })
                // https://github.com/efcore/EFCore.NamingConventions
                .UseSnakeCaseNamingConvention();
        });

        services.AddScoped<IDbContext>(provider => provider.GetService<TContext>());

        return services;
    }

    public static IApplicationBuilder UseMigration<TContext>(this IApplicationBuilder app, IWebHostEnvironment env)
        where TContext : DbContext, IDbContext
    {
        MigrateDatabaseAsync<TContext>(app.ApplicationServices).GetAwaiter().GetResult();

        if (!env.IsEnvironment("test"))
        {
            SeedDataAsync(app.ApplicationServices).GetAwaiter().GetResult();
        }

        return app;
    }


    // ref: https://github.com/pdevito3/MessageBusTestingInMemHarness/blob/main/RecipeManagement/src/RecipeManagement/Databases/RecipesDbContext.cs
    public static void FilterSoftDeletedProperties(this ModelBuilder modelBuilder)
    {
        Expression<Func<IAggregate, bool>> filterExpr = e => !e.IsDeleted;
        foreach (var mutableEntityType in modelBuilder.Model.GetEntityTypes()
                     .Where(m => m.ClrType.IsAssignableTo(typeof(IEntity))))
        {
            // modify expression to handle correct child type
            var parameter = Expression.Parameter(mutableEntityType.ClrType);
            var body = ReplacingExpressionVisitor
                .Replace(filterExpr.Parameters.First(), parameter, filterExpr.Body);
            var lambdaExpression = Expression.Lambda(body, parameter);

            // set filter
            mutableEntityType.SetQueryFilter(lambdaExpression);
        }
    }


    //ref: https://andrewlock.net/customising-asp-net-core-identity-ef-core-naming-conventions-for-postgresql/
    public static void ToSnakeCaseTables(this ModelBuilder modelBuilder)
    {
        foreach (var entity in modelBuilder.Model.GetEntityTypes())
        {
            // Replace table names
            entity.SetTableName(entity.GetTableName()?.Underscore());

            var tableObjectIdentifier =
                StoreObjectIdentifier.Table(entity.GetTableName()?.Underscore()!, entity.GetSchema());

            // Replace column names
            foreach (var property in entity.GetProperties())
            {
                property.SetColumnName(property.GetColumnName(tableObjectIdentifier)?.Underscore());
            }

            foreach (var key in entity.GetKeys())
            {
                key.SetName(key.GetName()?.Underscore());
            }

            foreach (var key in entity.GetForeignKeys())
            {
                key.SetConstraintName(key.GetConstraintName()?.Underscore());
            }
        }
    }

    private static async Task MigrateDatabaseAsync<TContext>(IServiceProvider serviceProvider)
        where TContext : DbContext, IDbContext
    {
        using var scope = serviceProvider.CreateScope();

        var context = scope.ServiceProvider.GetRequiredService<TContext>();
        await context.Database.MigrateAsync();
    }

    private static async Task SeedDataAsync(IServiceProvider serviceProvider)
    {
        using var scope = serviceProvider.CreateScope();
        var seeders = scope.ServiceProvider.GetServices<IDataSeeder>();
        foreach (var seeder in seeders)
        {
            await seeder.SeedAllAsync();
        }
    }
}