Fluent and Query Expression — Is there any benefit(s) of one over other?

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一向
一向 2020-11-22 05:15

LINQ is one of the greatest improvements to .NET since generics and it saves me tons of time, and lines of code. However, the fluent syntax seems to come much more natural

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  •  长情又很酷
    2020-11-22 05:48

    Neither is better: they serve different needs. Query syntax comes into its own when you want to leverage multiple range variables. This happens in three situations:

    • When using the let keyword
    • When you have multiple generators (from clauses)
    • When doing joins

    Here's an example (from the LINQPad samples):

    string[] fullNames = { "Anne Williams", "John Fred Smith", "Sue Green" };
    
    var query =
      from fullName in fullNames
      from name in fullName.Split()
      orderby fullName, name
      select name + " came from " + fullName;
    

    Now compare this to the same thing in method syntax:

    var query = fullNames
      .SelectMany (fName => fName.Split().Select (name => new { name, fName } ))
      .OrderBy (x => x.fName)
      .ThenBy  (x => x.name)
      .Select  (x => x.name + " came from " + x.fName);
    

    Method syntax, on the other hand, exposes the full gamut of query operators and is more concise with simple queries. You can get the best of both worlds by mixing query and method syntax. This is often done in LINQ to SQL queries:

    var query =
      from c in db.Customers
      let totalSpend = c.Purchases.Sum (p => p.Price)    // Method syntax here
      where totalSpend > 1000
      from p in c.Purchases
      select new { p.Description, totalSpend, c.Address.State };
    

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