EF Core - Create table if not exists

CreateTableIfNotExistsOperation.cs

using Microsoft.EntityFrameworkCore.Migrations.Operations;

namespace Gist.Extensions.Sql
{
  internal sealed class CreateTableIfNotExistsOperation : CreateTableOperation
  {
  }
}

CustomMigrationsSqlGenerator.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Migrations;
using Microsoft.EntityFrameworkCore.Migrations.Operations;
using Microsoft.EntityFrameworkCore.Migrations.Operations.Builders;

namespace Gist.Extensions.Sql
{
  public sealed class CustomMigrationsSqlGenerator : SqliteMigrationsSqlGenerator
  {
    public CustomMigrationsSqlGenerator(
      MigrationsSqlGeneratorDependencies dependencies,
      IRelationalAnnotationProvider migrationsAnnotations)
      : base(dependencies,
        migrationsAnnotations)
    {
    }

    protected override void Generate(
      MigrationOperation operation,
      IModel model,
      MigrationCommandListBuilder builder)
    {
      if (operation is CreateTableIfNotExistsOperation createTableIfNotExistsOperation)
      {
        Generate(createTableIfNotExistsOperation, model, builder);
      }
      else
      {
        base.Generate(operation, model, builder);
      }
    }

    private void Generate(CreateTableIfNotExistsOperation operation, IModel model, MigrationCommandListBuilder builder,
      bool terminate = true)
    {
      builder
        .Append("CREATE TABLE IF NOT EXISTS ")
        .Append(Dependencies.SqlGenerationHelper.DelimitIdentifier(operation.Name, operation.Schema))
        .AppendLine(" (");

      using (builder.Indent())
      {
        CreateTableColumns(operation, model, builder);
        CreateTableConstraints(operation, model, builder);
        builder.AppendLine();
      }

      builder.Append(")");

      if (terminate)
      {
        builder.AppendLine(Dependencies.SqlGenerationHelper.StatementTerminator);
        EndStatement(builder);
      }
    }
  }
}

GistDbContext.cs

using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Migrations;

namespace Gist.Extensions.Sql
{
  public class GistDbContext : DbContext {
    protected override void OnConfiguring(DbContextOptionsBuilder optionsBuilder) {
      optionsBuilder
        .UseSqlite($"Data Source={path};")
        .ReplaceService<IMigrationsSqlGenerator, CustomMigrationsSqlGenerator>(); //This line is required
    }
  }  
}

MigrationExtensions.cs

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Reflection;
using Microsoft.EntityFrameworkCore.Infrastructure;
using Microsoft.EntityFrameworkCore.Metadata;
using Microsoft.EntityFrameworkCore.Migrations;
using Microsoft.EntityFrameworkCore.Migrations.Operations;
using Microsoft.EntityFrameworkCore.Migrations.Operations.Builders;

namespace Gist.Extensions.Sql
{
  public static class MigrationExtensions
  {
    public static CreateTableBuilder<TColumns> CreateTableIfNotExists<TColumns>(
      this MigrationBuilder migrationBuilder,
      [NotNull] string name,
      [NotNull] Func<ColumnsBuilder, TColumns> columns,
      string schema = null,
      Action<CreateTableBuilder<TColumns>> constraints = null,
      string comment = null)
    {
      var createTableOperation = new CreateTableIfNotExistsOperation
      {
        Schema = schema,
        Name = name,
        Comment = comment
      };

      var columnsBuilder = new ColumnsBuilder(createTableOperation);
      var columnsObject = columns(columnsBuilder);
      var columnMap = new Dictionary<PropertyInfo, AddColumnOperation>();
      foreach (var property in typeof(TColumns).GetTypeInfo().DeclaredProperties)
      {
        var addColumnOperation = ((IInfrastructure<AddColumnOperation>)property.GetMethod.Invoke(columnsObject, null))
          .Instance;

        if (addColumnOperation.Name == null)
        {
          addColumnOperation.Name = property.Name;
        }

        columnMap.Add(property, addColumnOperation);
      }

      var builder = new CreateTableBuilder<TColumns>(createTableOperation, columnMap);
      constraints?.Invoke(builder);

      migrationBuilder.Operations.Add(createTableOperation);

      return builder;
    }
  }
}