What does this line mean?

Question

User-2121520658 posted

Hi

I am learning Web API. What does this mean? (please do not answer as it finds a product by its ID, I already know that, but I do not understand why it is written this way).

var product = products.FirstOrDefault((p) => p.Id == id);

This code is from : http://www.asp.net/web-api/overview/getting-started-with-aspnet-web-api/tutorial-your-first-web-api

Thank you

Answer 1

User1577371250 posted

Hi,

var product = products.FirstOrDefault((p) => p.Id == id);

1.  It will find the product with the specified ID.

2. FirstOrDefault() will return the First Product from the products where Product.Id == id.

Suppose if the product with the ID is not found then NULL will be returned.

You can write as follows as well

var product = products.Where(p=> p.Id == id).FirstOrDefault();

Answer 2

User2024324573 posted

It is LINQ expression, know more about it at : https://msdn.microsoft.com/en-us/library/bb397926.aspx

It replaces the SQL query that we used to write to work with database. With the evolution of LINQ and Entity Framework now it is easy to write queries within the code.

As Lokesh B R explained the expression, it will just return the product which will first match with the id parameter.