Fetching childrens of an entity in Entity Framework

Question

I have an entity called

Public Class Equipment { int Id; string EquipmentName; int? ParentEquipmentId; }

So have this entity where an equipment can have a parent and child relationship. I want to fetch the parent equipment and also all the children of the equipment associated with it.

Can i have ICollection on the entity to fetch me the childrens??

possible duplicate of How to include a child object's child object in Entity Framework 5 — Kritner
– Kritner, Commented Oct 31, 2014 at 11:45

garyson ford · Accepted Answer · 2014-11-01 04:47:43Z

Public Class Equipment { int Id; string EquipmentName; int? ParentEquipmentId; virtual Equipment Parent; Virtual ICollection<Equipment> Childrens }

Model binder use fluent api

 this.HasOptional(e => e.Parent) .WithMany(e => e.Children) .HasForeignKey(m => m.ParentEquipmentId);

This will pull the records associated with the

Wojciech · Accepted Answer · 2014-10-31 11:47:10Z

0

Yes you need to include collection of children in your object:

public virtual ICollection<Equipment> Children { get; set; }

and remember to add .Include(q => q.Children) to your linq query to load children.

answered Oct 31, 2014 at 11:47

Wojciech

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2 Comments

garyson ford Over a year ago

do i have to write fluent api cause this is not working

Wojciech Over a year ago

You can but you don't need to. Try to have you entity loaded properly first as it is. Then when you have it working add collection of children and in the query and 'Include' to load children. Also remember to initialize your collection in the constructor. If this doesn't answer your question please provide more details for my better understanding.

xwrs · Accepted Answer · 2014-10-31 11:51:56Z

Seems that you need something like this (not the precise syntax)

Parent and Children properties:

public Equipment Parent { get { return dataContext.DbSet<Equipment>().SingleOrDefault(e=>e.Id == this.ParentEquipmentId); } } public IEnumerable<Equipment> Children { get { return dataContext.DbSet<Equipment>().Where(e=>e.ParentEquipmentId == this.Id); } }

And use your Parent property to get all child Equipment of this particular parent:

this.Parent.Children

Use var allSubchild = this.Children.SelectMany(c => c.Children);

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