c# - LINQ select statement with many to many -

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i have relationship, project categories. relation many many have 3 tables: project / project_has_category / categories.

i need select projects has relation category (by id)

project class

public class project {     public int projectid { get; set; }      public virtual icollection<category> categories { get; set; } }

category class

public class category {     public int categoryid { get; set; }     public string categoryname { get; set; }      public virtual icollection<project> projects { get; set; } }

i have tried following:

[httppost] public actionresult projects(string catid, string strsearch) {     var cats = adapter.categoryrepository.get();     var projects = adapter.projectrepository.get().where(x => x.categories.contains(catid));     /*also*/     var projects = adapter.projectrepository.get().where(x => cats.contains(catid));     return view(projects); }

but gives error:

the best overloaded method match 'system.collections.generic.icollection.contains(libmodels.category)' has invalid arguments c:\users\thomas\desktop\freelauncher1005\freelauncher\controllers\projectcontroller.cs

what doing wrong?

categories list of category objects, can't search integer id contains method (check signature of method - requires category object search for):

  var projects = adapter.projectrepository.get()                         .where(x => x.categories.contains(catid)) // error

use any check if there category object id equal value:

  var projects = adapter.projectrepository.get()                         .where(x => x.categories.any(c => c.categoryid == catid))

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