EF LINQ include multiple and nested entities

Question

Ok  I have tri-leveled entities with the following hierarchy  Course -  Module -  Chapter  Here was the original EF LINQ statement   Course course   db Courses                  Include i   gt  i Modules Select s   gt  s Chapters                    Single x   gt  x Id    id      Now  I want to include another entity called Lab which is associated with a course   How do I include the Lab entity   I tried the following but it didn t work   Course course   db Courses                  Include i   gt  i Modules Select s   gt  s Chapters   amp  amp  i Lab                   Single x   gt  x Id    id      Any ideas on including the 2nd Entity   Any piece of advise or information would be highly appreciated  Thanks

User · Answer

this is from my project  var saleHeadBranch   await  context SaleHeadBranch   Include d   gt  d SaleDetailBranch    ThenInclude d   gt  d Item    Where d   gt  d BranchId    loginTkn branchId    FirstOrDefaultAsync d   gt  d Id    id

User · Answer

You can also try  db Courses Include  Modules Chapters   Single c   gt  c Id    id

User · Answer

Have you tried just adding another Include   Course course   db Courses                  Include i   gt  i Modules Select s   gt  s Chapters                    Include i   gt  i Lab                   Single x   gt  x Id    id     Your solution fails because Include doesn t take a boolean operator  Include i   gt  i Modules Select s   gt  s Chapters   amp  amp           i Lab                                                                                             list           bool operator    other list   Update To learn more  download LinqPad and look through the samples  I think it is the quickest way to get familiar with Linq and Lambda   As a start - the difference between Select and Include is that that with a Select you decide what you want to return  aka projection   The Include is a Eager Loading function  that tells Entity Framework that you want it to include data from other tables   The Include syntax can also be in string  Like this              db Courses              Include  Module Chapter                Include  Lab                Single x   gt  x Id    id     But the samples in LinqPad explains this better

User · Answer

Include is a part of fluent interface  so you can write multiple Include statements each following other   db Courses Include i   gt  i Modules Select s   gt  s Chapters               Include i   gt  i Lab              Single x   gt  x Id    id

User · Answer

One may write an extension method like this            lt summary gt          Includes an array of navigation properties for the specified query           lt  summary gt           lt typeparam name  T  gt The type of the entity lt  typeparam gt           lt param name  query  gt The query to include navigation properties for that lt  param gt           lt param name  navProperties  gt The array of navigation properties to include lt  param gt           lt returns gt  lt  returns gt      public static IQueryable lt T gt  Include lt T gt  this IQueryable lt T gt  query  params string   navProperties          where T   class               foreach  var navProperty in navProperties              query   query Include navProperty            return query          And use it like this even in a generic implementation   string   includedNavigationProperties   new string      NavProp1 SubNavProp    NavProp2      var query   context Set lt T gt     Include includedNavigationProperties

User · Answer

In Entity Framework Core  EF core  you can use  ThenInclude for including next levels   var blogs   context Blogs      Include blog   gt  blog Posts           ThenInclude post   gt  post Author       ToList      More information  https   docs microsoft com en-us ef core querying related-data  Note  Say you need multiple ThenInclude   on blog Posts  just repeat the Include blog   gt  blog Posts  and do another ThenInclude post   gt  post Other    var blogs   context Blogs      Include blog   gt  blog Posts           ThenInclude post   gt  post Author       Include blog   gt  blog Posts           ThenInclude post   gt  post Other    ToList

[.net] EF LINQ include multiple and nested entities

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