How to make a list from multiple rows from inner join in Entity Framework Core?

Question

How to make a list from multiple rows from inner join in Entity Framework Core?

asp.net-core c# entity-framework entity-framework-core linq

Question

I have a view model called Pictures like

Public class PicturesViewModel
{
    public string Name;
    Public List<String> FileNames;
}

and I have 2 tables in a SQL Server database, Names and FileNames, where the idname in FileNames is a foreign key to id in Names.

This screenshot shows the 2 tables

I use Entity Framework Core in an ASP.NET Core MVC project. I have to use the database first method and I want to fill PicturesViewModel class in my controller and send it to a view.

The problem is that I can't find a way to create a PicturesViewModel object from DbContext with linq and Entity Framework. The only way I can consider is to do it by C# (for or foreach) and do it with 2 steps:

first filling Name
then filling FileNames with a for/foreach loop

Is there another way in Linq or Entity Framework to create a list from an inner join in dbContext ?

H. Harati

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D3ivid · Accepted Answer · 7/7/2018 8:27:44 AM

Model:

Public class Filenames
{
    public decimal idName { get; set; }
    public string fileNames { get; set; }
    public Names Names { get; set; }
}

Public class Names 
{
    public decimal id { get; set; }
    public string Name { get; set; }
}

Basically:

With Join basic (Bad) =>

Context.Names.Join(Context.Names.Filenames,
                   nam => nam.id,
                   fil => fil.idName,
                   (nam, fil) => new { filename = fil, names = nam });

With Navigation properties (Common in DB First) =>

Context.Names.Include("Filenames");
Context.Names.Include(ent => ent.Filenames);

How to make a list from multiple rows from inner join in Entity Framework Core?

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