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Posted on

Entity Framework: eager and lazy loading

  • lazy loading:
    • delaying load of data until we specifically request for it
    • i.e. accessing customer.Address loads Address of a customer in the background via separate SQL query
    • property needs to be public, virtual
    • context.Configuration.ProxyCreationEnabled should be true
    • context.Configuration.LazyLoadingEnabled should be true
    • to disable lazy loading completely Context.Configuration.LazyLoadingEnabled = false;
  • eager loading
    • opposite of lazy loading
    • loads related entities as part of the query
    • done via .Include() query

Further read:

https://www.entityframeworktutorial.net/lazyloading-in-entity-framework.aspx

https://www.entityframeworktutorial.net/eager-loading-in-entity-framework.aspx

Posted on

Pattern matching

Pattern matching is used for:

  • testing expression to check if some value have certain characteristics
  • safer compare because ‘==’ and ‘!=’ can be overloaded

Examples:

a is int number
sequence is IList<T> list

switch statement:

command switch
{
   Operation.SystemTest => RunDiagnostics(),
   Operation.Start => StartSystem(),
   Operation.Stop => StopSystem(),
   Operation.Reset => ResetToReady(),
   _ => throw new ArgumentException("Invalid enum value for command", nameof(command)),
};

switch with ranges:

tempInFahrenheit switch
{
    (> 32) and (< 212) => "liquid",
    < 32 => "solid",
    > 212 => "gas",
    32 => "solid/liquid transition",
    212 => "liquid / gas transition",
};

collection pattern matching:

array is [1,1,2,3,5,8, ..]

Further read:

https://learn.microsoft.com/en-us/dotnet/csharp/fundamentals/functional/pattern-matching