Expose loader IQueryable on ILazyLoader

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Assessment

Difficulty
5/5
Estimated time
Over a week
Newbie friendliness
25/100
Issue type
Feature
Clarity
Mostly clear
Activity status
Stale
Tech stack
csharp
Domain
databases

Research direction

Start by reviewing ILazyLoader and its Load method in the EF Core 3.1.1 codebase, with the Lesson and Topics example as the usage case. Determine the API needed to expose an IQueryable for a lazy-loaded collection and verify that an IsValid filter can be applied at the database level through the SQL Server provider.

Written by the indexing model from the issue text.

Description

area-change-tracking customer-reported

Hi,

I have entity which contains other entities inside. I'm using ILazyLoader to load them when needed, but I want to filter them. How can I filter them?

Lets say I have:

 public class Lesson : EntityBase
    {
	    private readonly ILazyLoader _lazyLoader;

	    public Lesson(ILazyLoader lazyLoader)
	    {
		    _lazyLoader = lazyLoader;
	    }

            [Required]
		public List<Topic> Topics
		{
			get => _lazyLoader.Load(this, ref _topics);
			set => _topics = value;
		}

              private List<Topic> _topics;

I want to access lesson.Grades, but my grades should be filtered by IsValid field.

At the moment it will load all the grades.

I understand I can do _lazyLoader.Load(this, ref _topics).Where(x => x.IsValid).ToList();, but I want filter in database level

Is this possible?

Include provider and version information

EF Core version: 3.1.1
Database provider: Microsoft.EntityFrameworkCore.SqlServer
Target framework: Core 3.1

Dominant language
C#
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