I have two objects named LastFiles and DbObj. When I pull the data, I have 2 object lists consisting of these. I created a scenario like this.

public class LastFiles
{
    public int Id { get; set; }
    public string Title { get; set; }
    public string Author { get; set; }
    public string Translator { get; set; }
    public string Supervisor { get; set; }
    public string Type { get; set; }
    public string FileName { get; set; }
    public string ModifiedDate { get; set; }
}

public class DbObj
{
    public int Id { get; set; }
    public int WorkId { get; set; }
    public string Type { get; set; }
    public int TypeId { get; set; }
}

var lastFiles = new List<LastFiles> {
    new LastFiles { Id = 1, Title = "Title 1", Author = "Author 1", Type = "book", FileName = "file-name-1.pdf" },
    new LastFiles { Id = 2, Title = "Title 2", Author = "Author 2", Type = "book", FileName = "file-name-2.pdf" },
    new LastFiles { Id = 3, Title = "Title 3", Author = "Author 3", Type = "article", FileName = "file-name-3.pdf" },
    new LastFiles { Id = 4, Title = "Title 4", Author = "Author 4", Type = "article", FileName = "file-name-4.pdf" },
    new LastFiles { Id = 5, Title = "Title 5", Author = "Author 5", Supervisor = "Supervisor 1", Type = "thesis", FileName = "file-name-5.pdf" },
    new LastFiles { Id = 6, Title = "Title 6", Author = "Author 6", Supervisor = "Supervisor 2", Type = "thesis", FileName = "file-name-6.pdf" }
};

var dbObj = new List<DbObj> {
    new DbObj { Id = 1, WorkId = 5, Type = "book", TypeId = 1 },
    new DbObj { Id = 2, WorkId = 5, Type = "book", TypeId = 2 },
    new DbObj { Id = 3, WorkId = 5, Type = "thesis", TypeId = 5 },
    new DbObj { Id = 4, WorkId = 5, Type = "thesis", TypeId = 6 },
    new DbObj { Id = 5, WorkId = 278, Type = "article", TypeId = 689 }
};

If I have to go through the scenario; How can I get items from lastFiles that LastFiles.Type value is the same as the DbObj.Type value and the LastFiles.Id is the same as the DbObj.TypeId?

CodePudding user response：

You can use an anonymous object to join two collections like below :

var result = (from lf in lastFiles
                      join db in dbObj on new { lf.Type, TypeId = lf.Id}
                                   equals new  { db.Type, db.TypeId} 
                      select lf).ToList();

Edit

Lambda version of the join :

var result2 = lastFiles.Join(dbObj,lf=> new {lf.Type,TypeId = lf.Id},db=>new  { db.Type,db.TypeId},(lf,db)=> lf  ).ToArray();

Fiddle

Please note that property names and types should match. You may need renames and casts in actual code.