This document is a presentation by Vedran Maršić, focusing on dynamic LINQ and expression trees in C#. It covers topics including the creation and parsing of expression trees, dynamic queries in Entity Framework, and various advanced features in C# 6.0. Additionally, it lists resources for further learning and examples of expression tree implementations.

1. Road to Dynamic
LINQ – Part 2
Vedran Maršić AKA Fosna
Warning: Expression Trees Ahead

2. About me
 Vedran Maršić AKA Fosna
 dev at http://www.axilis.com/author/vmarsic/
 organizing programming workshops for kids
 Logo, Scratch, HTML, CSS, JavaScript, Python, C++

3. We’ll cover
 Part 1
 What is expression tree in C#
 How is it different from similar looking lambda delegates
 How to build expression trees
 How to parse expression trees
 Where are you already using them
 Part 2
 Check out few expression tree exploits
 Point to brilliant, not easy to understand, ideas or projects from some cool developer
maniacs 

4. We won’t cover
 Implementing LINQ providers
 Implementing deep copy
 Implementing faster static dictionary
 Implementing IoC container

5. Need for Dynamic Queries

9. Applied Expression Trees
C# 6.0 Taste Before C# 6.0

10. Sort by Custom Property
... in LINQ to Entity Framework
 Try to support sort by each column in grid on web page
 Chances are grid will send to the server
 a string for property name
 and a sort order

11. Dynamic Searching
... in LINQ to Entity Framework
 Try to support search by each column in grid on web page
 Chances are grid will send to the server
 a property name
 and a value to compare to
 Let’s not bother with more complex requirements for brevity of the presentation

12. Get Property or Method Names
Something like nameof operators in C# 6.0
Similar thing was possible with older compiler
Hint:

13. Get Over NULL Reference Exceptions
 Null-conditional operators in C# 6.0
 Empty string if person is null or person.Child is null
 Simmilar thing was possible with older compiler
string childName = person.Safely(x => x.Child.Name);

14. Source Code Available at
https://github.com/axilis/RoadToDynamicLinq

15. Some Other Ideas
 LINQ update, insert, delete statement with where clause
 without dbContext.SaveChanges() magic
 Entity Framework Extended Library by Paul Welter of LoreSoft
 https://github.com/loresoft/EntityFramework.Extended
 TypeSafe property changed
 http://stackoverflow.com/questions/3551947/in-c-why-expression-trees-and-when-
do-you-need-to-use-them/3551991#3551991
 Lambda equality comparer with delegates

16. Stay Away from Other Ideas 
 Deep copy
 Customizable convention based copy, like AutoMapper
 Fast IoC Container
 BarbarianIOC : A simple IOC Container by Sacha Barber, 25 Feb 2013
 http://www.codeproject.com/Articles/552514/BarbarianIOC-A-simple-IOC-Container
 Faster static dictionary
 StaticStringDictionary - Fast Switching With LINQ Revisited, AUG 28TH, 2008, by Gustavo Guerra
 http://functionalflow.co.uk/blog/2008/08/28/staticstringdictionary-fast-switching-with-linq-revisited/
 Your own LINQ provider
 Using Expression Trees in Your APIs by Patrick Steele04/01/2011
 https://visualstudiomagazine.com/Articles/2011/04/01/pccsp_Expression-Trees.aspx

17. Thanks. Bye!
No questions, right?

18. Resources
 Start with
 http://stackoverflow.com/a/403233/953338
 Expression Tree Basics, Charlie Calvert 31 Jan 2008 3:49 AM
 http://blogs.msdn.com/b/charlie/archive/2008/01/31/expression-tree-basics.aspx
 Published by Olexander Ivanitskyi on Tuesday, June 11, 2013
 LINQ: Func<T> vs. Expression<Func<T>>
 http://ivanitskyi.blogspot.hr/2013/06/linq-func-vs-expression.html
 asked Apr 27 '09 at 13:50, Richard Nagle
 Why would you use Expression<Func<T>> rather than Func<T>?
 http://stackoverflow.com/questions/793571/why-would-you-use-expressionfunct-
rather-than-funct

19. Resources
 Dynamic LINQ examples
 https://www.nuget.org/packages/System.Linq.Dynamic/
 C# 6.0 Features
 https://github.com/dotnet/roslyn/wiki/New-Language-Features-in-C%23-6
 Canonical Functions
 https://msdn.microsoft.com/en-us/library/vstudio/bb738626(v=vs.100).aspx
 The .NET Programmer’s Playground - LinqPad
 http://www.linqpad.net/