public static void UseLinqExampleOne()
{
var books = new LINQ.Classes.BookRepository().GetBooks();
//LINQ Extension Methods
var cheapBooks = books
.Where(x => x.Price < 10)
.OrderBy(x => x.Title)
.Select(x => x.Title);
foreach (var book in cheapBooks)
{
Console.WriteLine(book);
//Console.WriteLine(book.Title + " " + book.Price);
}
}
public static void UseLinqExamplesTwo()
{
var books = new LINQ.Classes.BookRepository().GetBooks();
//Use Single when one and only one object satisfies the condition, if no match an exception will be thrown
var book = books.Single(x => x.Title == "Angular JS");
Console.WriteLine(book.Title);
//Use SingleOrDefault when you are not sure if only one objects matches. Null will be returned if it doesn't and it won't throw an execption
var book2 = books.SingleOrDefault(x => x.Title == "Angular Forever");
Console.WriteLine(book2 != null ? book2.Title : "Book2 was null");
//Use First to get the first object in a collection that matches the predicate
//Use FirstOrDefault if you want to return null and not an exception on a non match
//Use Last or LastOrDefault which is self explanatory at this point
var firstBook = books.First(x => x.Title == "Pro ASP.NET MVC 5");
Console.WriteLine(firstBook.Title + " " + firstBook.Price);
//Use Skip and Take ... does what they say
var pagedBooks = books.Skip(2).Take(3); //skip first two records and the next three
foreach (var pagedBook in pagedBooks)
{
Console.WriteLine(pagedBook.Title);
}
//Use count to items in the collection
Console.WriteLine($"Num of books in collection: {books.Count()}");
//Use Min and Max to get the lowest and highest values
Console.WriteLine($"Highest priced book: {books.Max(x => x.Price)}"); //highest priced book
Console.WriteLine($"Lowest priced book: {books.Min(x => x.Price)}"); //lowest priced book
Console.WriteLine($"Total amount of all books: {books.Sum(x => x.Price)}"); //total price of all books
Console.WriteLine($"Average price of all books: {books.Average(x => x.Price)}");
}
