CODEWITHSUNDEEP
syntaxentity-framework-5
user2480201
user2480201

Reputation: 151

Entity Framework Syntax for Beginners

Can anyone please help me with a general Entity Framework question? I'm a newbie and trying to teach myself from reading and trial & error. However, I'm getting REALLY confused on all the syntax and terminology. And the more I google, the more confused I get!

  1. What in the world are those little arrows (=>) used in the syntax? And I'm not even sure what the name of the syntax is...is it Entity Framework syntax? Linq to method syntax? Linq to Entity syntax?

  2. Why does it seem like you can use random letters when using that syntax? the "f" below seems interchangeable with any alphabet letter since Intellisense gives me options no matter what letter I type. So what is that letter supposed to stand for anyway? There seems to be no declaration for it.

    var query = fruits.SelectMany(f => f.Split(' '));

  3. Is it better to use the syntax with the little arrows or to use the "psuedo SQL" that I keep seeing, like below. This seems a little easier to understand, but is this considered not the Real Entity Framework Way?

    var query = from f in fruits from word in f.Split(' ') select word;

  4. And, for any of them - is there any documentation out there ANYWHERE?? I've been scouring the internet for tutorials, articles, anything, but all that comes back are small sample queries varying with the little arrows or that psuedo SQL, with no explanations beyond "here's how to do a select:"

I would much appreciate any guidance or assistance. I think if I can just find out where to start, then I can build myself from there. Thanks!

Upvotes: 3

Views: 4742

Answers (2)

Erik Funkenbusch
Erik Funkenbusch

Reputation: 93444

The arrow is called a Lambda operator, and it's used to create Lambda expressions. This has nothing to do with EF, or Linq or anything else. It's a feature of C#. EF and Linq just use this feature a lot because it's very useful for writing queries.

Marco has given links to the relevant documentation.

Linq is a library of extension methods that primarily operate on types like IEnumerable and IQueryable interfaces, and give you a lot of power to work with collections of various types. You can write Linq queries either in two formats, so called Method syntax and Query Syntax. They are functionally identical, but their usage is generally a matter of personal preference which one you use (although many of us use both, depending on the context it's used in.. one or the other is easier to use).

Upvotes: 1

MeTitus
MeTitus

Reputation: 3428

There is no real entity way, there is LINQ and there is LINQ extension methods which is my opinion is much cleaner to the eyes. Also you can use LINQ not just with EE.

Language Integrated Query

LINQ extends the language by the addition of query expressions, which are akin to SQL statements, and can be used to conveniently extract and process data from arrays, enumerable classes, XML documents, relational databases, and third-party data sources. Other uses, which utilize query expressions as a general framework for readably composing arbitrary computations, include the construction of event handlers2 or monadic parsers.3

1 It is called lambda expression and it is basically an anonymous method.

Exploring Lambda Expression in C#

2 You can use anything you want, word, or letters, anything that is a valid name for a parameter, because that is a parameter

3 I find the LINQ extension methods to be cleaner, and to be honest the last I want to see is SQL like statements laying in the code.

4 A good start can be found here

101 LINQ SAMPLES

Upvotes: 2

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