LINQ & ADO.NET Entity Framework * 1/14/201907/16/96 .NET Team LINQ & ADO.NET Entity Framework Stefan Dobrev GM Avaxo Ltd. http://ligaz.blogspot.com (c) 2005 National Academy for Software Development - http://academy.devbg.org. All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

Contents LINQ – general stuff LINQ Providers ADO.NET Entity Framework * 1/14/201907/16/96 Contents LINQ – general stuff LINQ Providers ADO.NET Entity Framework (c) 2005 National Academy for Software Development - http://academy.devbg.org. All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

Language Integrated Query * 1/14/201907/16/96 LINQ Language Integrated Query (c) 2005 National Academy for Software Development - http://academy.devbg.org. All rights reserved. Unauthorized copying or re-distribution is strictly prohibited.*

DEMO LINQ in Action

Local variable type inference What we saw? Query expressions var func = from l in ProgrammingLanguage.GetAll() where l.Paradigm.HasValue(Functional) select l; Local variable type inference var func = ProgrammingLanguage.GetAll() .Where(l => l.Paradigm.HasValue(Functional)) .Select(l => l); Extension methods Lambda expressions Expression Trees

Local Variable Type Inference int i = 5; string s = "Hello"; double d = 1.0; int[] numbers = new int[] {1, 2, 3}; Dictionary<int,Order> orders = new Dictionary<int,Order>(); var i = 5; var s = "Hello"; var d = 1.0; var numbers = new int[] {1, 2, 3}; var orders = new Dictionary<int,Order>(); Compiler infers the correct type from the right side

Bring extensions into scope Extension Methods obj.Foo(x, y)  XXX.Foo(obj, x, y) namespace ITBoxing { public static class Extensions public static string HasValue( this ProgrammingParadigm paradigm, ProgrammingParadigm value ) return ( paradigm & value ) != 0 } Extension Method Bring extensions into scope using ITBoxing IntelliSense ProgrammingParadigm paradigm = Functional & Imperative; Paradigm.HasValue(Imperative);

Lambda Expressions Lambda expression List<ProgrammingLanguage> langs = ProgrammingLanguage.GetAll(); List<ProgrammingLanguage> cool = langs.FindAll( delegate(ProgrammingLanguage l) { return l.IsCool; } ); List<ProgrammingLanguage> langs = ProgrammingLanguage.GetAll(); List<ProgrammingLanguage> cool = langs.FindAll(l => l.IsCool); Lambda expression

Expression Trees Code as Data public delegate bool Predicate<T>(T item); Expression<Predicate<ProgrammingLanguage>> isCool = l => l.IsCool == true; ParameterExpression l = Expression.Parameter( typeof(ProgrammingLanguage), "l" ); Expression expr = Expression.Equal( Expression.Property(l, typeof(ProgrammingLanguage) .GetProperty("IsCool")), Expression.Constant(true)); Expression<Predicate <ProgrammingLanguage>> isCool = Expression.Lambda <Predicate<ProgrammingLanguage>>(expr, l);

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