Entity Framework - Include Multiple Levels of Properties

Question

The Include   method works quite well for Lists on objects  But what if I need to go two levels deep  For example  the method below will return ApplicationServers with the included properties shown here  However  ApplicationsWithOverrideGroup is another container that holds other complex objects  Can I do an Include   on that property as well  Or how can I get that property to fully load   As it stands now  this method   public IEnumerable lt ApplicationServer gt  GetAll         return this Database ApplicationServers          Include x   gt  x ApplicationsWithOverrideGroup                           Include x   gt  x ApplicationWithGroupToForceInstallList           Include x   gt  x CustomVariableGroups                           ToList        Will populate only the Enabled property  below  and not the Application or CustomVariableGroup properties  below   How do I make this happen   public class ApplicationWithOverrideVariableGroup   EntityBase       public bool Enabled   get  set        public Application Application   get  set        public CustomVariableGroup CustomVariableGroup   get  set

User · Answer

EF Core  Using  ThenInclude  to load mutiple levels  For example   var blogs   context Blogs      Include blog   gt  blog Posts           ThenInclude post   gt  post Author           ThenInclude author   gt  author Photo       ToList

User · Answer

I made a little helper for Entity Framework 6   Net Core style   to include sub-entities in a nice way   It is on NuGet now   Install-Package ThenInclude EF6  using System Data Entity   var thenInclude   context One Include x   gt  x Twoes       ThenInclude x  gt  x Threes       ThenInclude x  gt  x Fours       ThenInclude x  gt  x Fives       ThenInclude x   gt  x Sixes       Include x  gt  x Other       ToList      The package is available on GitHub

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I figured out a simplest way  You don t need to install package ThenInclude EF or you don t need to use ThenInclude for all nested navigation properties  Just do like as shown below  EF will take care rest for you  example  var thenInclude   context One Include x   gt  x Twoes Threes Fours Fives Sixes   Include x  gt  x Other   ToList

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I also had to use multiple includes and at 3rd level I needed multiple properties    from e in context JobCategorySet                       where e Id    id  amp  amp                              e AgencyId    agencyId                       select e                         Include x   gt  x JobCategorySkillDetails                         Include x   gt  x Shifts Select r   gt  r Rate  Select rt   gt  rt DurationType                          Include x   gt  x Shifts Select r   gt  r Rate  Select rt   gt  rt RuleType                          Include x   gt  x Shifts Select r   gt  r Rate  Select rt   gt  rt RateType                          FirstOrDefaultAsync      This may help someone

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Let me state it clearly that you can use the string overload to include nested levels regardless of the multiplicities of the corresponding relationships  if you don t mind using string literals   query Include  Collection Property

User · Answer

The EFCore examples on MSDN show that you can do some quite complex things with Include and ThenInclude  This is a good example of how complex you can get  this is all one chained statement    viewModel Instructors   await  context Instructors         Include i   gt  i OfficeAssignment          Include i   gt  i CourseAssignments           ThenInclude i   gt  i Course               ThenInclude i   gt  i Enrollments                   ThenInclude i   gt  i Student          Include i   gt  i CourseAssignments           ThenInclude i   gt  i Course               ThenInclude i   gt  i Department          AsNoTracking          OrderBy i   gt  i LastName         ToListAsync     You can have multiple Include calls - even after ThenInclude and it kind of  resets  you back to the level of the top level entity  Instructors   You can even repeat the same  first level  collection  CourseAssignments  multiple times followed by separate ThenIncludes commands to get to different child entities  Note your actual query must be tagged onto the end of the Include or ThenIncludes chain  The following does NOT work  var query    context Instructors AsQueryable    query Include i   gt  i OfficeAssignment    var first10Instructors   query Take 10  ToArray     Would strongly recommend you set up logging and make sure your queries aren t out of control if you re including more than one or two things  It s important to see how it actually works - and you ll notice each separate  include  is typically a new query to avoid massive joins returning redundant data  AsNoTracking can greatly speed things up if you re not intending on actually editing the entities and resaving   EFCore 5 made some changes to the way queries for multiple sets of entities are sent to the server  There are new options for Split Queries which can make certain queries of this type far more efficient with fewer joins  but make sure to understand the limitations

User · Answer

For EF 6  using System Data Entity   query Include x   gt  x Collection Select y   gt  y Property     Make sure to add using System Data Entity  to get the version of Include that takes in a lambda     For EF Core  Use the new method ThenInclude  query Include x   gt  x Collection        ThenInclude x   gt  x Property

User · Answer

If I understand you correctly you are asking about including nested properties  If so     Include x   gt  x ApplicationsWithOverrideGroup NestedProp    or   Include  ApplicationsWithOverrideGroup NestedProp       or   Include    nameof ApplicationsWithOverrideGroup    nameof NestedProp

User · Answer

I m going to add my solution to my particular problem  I had two collections at the same level I needed to include  The final solution looked like this  var recipe    bartendoContext Recipes      Include r   gt  r Ingredients       ThenInclude r   gt  r Ingredient       Include r   gt  r Ingredients       ThenInclude r   gt  r MeasurementQuantity       FirstOrDefault r   gt  r Id    recipeId   if  recipe  Ingredients    null  return 0m  var abv   recipe Ingredients Sum ingredient   gt  ingredient Ingredient AlcoholByVolume   ingredient MeasurementQuantity Quantity   return abv   This is calculating the percent alcohol by volume of a given drink recipe  As you can see I just included the ingredients collection twice then included the ingredient and quantity onto that

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