EF Core Database Helper Methods and Concepts

Here's a concise note summarizing the Entity Framework Core (EF Core) database helper methods and concepts from your code:

1. Database Initialization & Migration

using(ApplicationDbContext context = new())
{
    context.Database.EnsureCreated();
    if (context.Database.GetPendingMigrations().Count() > 0) 
    {
        context.Database.Migrate();
    }
}

• Ensures database is created.

• Applies pending migrations automatically.

2. Logging Configuration

protected override void OnConfiguring(DbContextOptionsBuilder options)
{
    options.UseSqlServer("connectionString")
           .LogTo(Console.WriteLine, new[] { DbLoggerCategory.Database.Command.Name }, LogLevel.Information);
}

• Logs SQL commands executed by EF Core to the console with Information log level.

3. Get All Books

void GetAllBooks()
{
    using var context = new ApplicationDbContext();
    var books = context.Books.ToList();
    foreach (var book in books)
        Console.WriteLine(book.Title + " - " + book.ISBN);
}

4. Add a Book

void AddBook()
{
    Book book = new() { Title = "New EF Core Book", ISBN = "1231231212", Price = 10.93m, Publisher_Id = 1 };
    using var context = new ApplicationDbContext();
    context.Books.Add(book);
    context.SaveChanges();
}

5. Get One Book (First or Default)

void GetBook()
{
    using var context = new ApplicationDbContext();
    var book = context.Books.FirstOrDefault();
    Console.WriteLine(book?.Title + " - " + book?.ISBN);
}

6. Filtering with Where

var book = context.Books.Where(u => u.Publisher_Id == 3 && u.Price > 30).FirstOrDefault();

7. Find by Primary Key

var book = context.Books.Find(1002);

8. Single or Default

var book = context.Books.SingleOrDefault(u => u.Publisher_Id == 66);

• Throws if multiple matches exist.

9. Contains, Like, Aggregation

var books = context.Books.Where(u => EF.Functions.Like(u.ISBN, "12%"));

10. Deferred Execution

var books = context.Books; // Query is not executed yet
foreach (var book in books)
    Console.WriteLine(book.Title + " - " + book.ISBN); // Query executes here

11. Pagination (Skip and Take)

var books = context.Books.Skip(4).Take(1);

12. Update Books

void UpdateBook()
{
    using var context = new ApplicationDbContext();
    var books = context.Books.Where(u => u.Publisher_Id == 1);
    foreach (var book in books)
        book.Price = 55.55m;
    context.SaveChanges();
}

13. Delete Book

void DeleteBook()
{
    using var context = new ApplicationDbContext();
    var book = context.Books.Find(1003);
    context.Books.Remove(book);
    context.SaveChanges();
}

This covers the main database helper methods and EF Core concepts demonstrated in your code snippet, including CRUD operations, filtering, pagination, and logging. Let me know if you want a more detailed explanation or examples!