Navigation in linq.

Hi Shourabh,

When you want bring relational data at same time that time navigation properties used. You can use .Include() to do eager loading in Linq. Lets take Example which will help you,

public partial class Student
{
public Student()
{
this.Courses = new List();
}
public int StudentID { get; set; }
public string StudentName { get; set; }
public Nullable<int> StandardId { get; set; }
public byte[] RowVersion { get; set; }
public virtual Standard Standard { get; set; }
public virtual StudentAddress StudentAddress { get; set; }
public virtual List Courses { get; set; }
}
public partial class Standard
{
public Standard()
{
this.Teachers = new List();
}
public int StandardId { get; set; }
public string StandardName { get; set; }
public string Description { get; set; }
public virtual List Teachers { get; set; }
}
// Now lets do eager loaging using .Include() for Standard
using (var context = new DbContext())
{
var stud1 = context.Students
.Include("Standard")
.Where(s => s.StudentName == "Shourabh")
.FirstOrDefault();
}
// No Lets do eager loading for teacher class
using (var context = new DbContext())
{
var stud1 = context.Students.Include(s => s.Standard.Teachers)
.Where(s => s.StudentName == "Bill")
.FirstOrDefault();
}

4 Replies

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Sachin Singh5y ago
Accepted answer
for child of child
return dbcontext.parent
.Include(a => a.Children).ThenInclude(c => c.ChildRelationshipType);
Mageshwaran R5y ago
Hi Sourabh,
Please refer this link,
https://docs.microsoft.com/en-us/dotnet/framework/data/adonet/ef/language-reference/query-expression-syntax-examples-navigating-relationships#:~:text=Navigation%20properties%20allow%20a%20user,in%20LINQ%20to%20Entities%20queries.
Jignesh Kumar5y ago
Hi Shourabh,

When you want bring relational data at same time that time navigation properties used. You can use .Include() to do eager loading in Linq. Lets take Example which will help you,
public partial class Student
{
    public Student()
    {
        this.Courses = new List();
    }

    public int StudentID { get; set; }
    public string StudentName { get; set; }
    public Nullable<int> StandardId { get; set; }
    public byte[] RowVersion { get; set; }

    public virtual Standard Standard { get; set; }
    public virtual StudentAddress StudentAddress { get; set; }

   public virtual List Courses { get; set; }
}

public partial class Standard
{
    public Standard()
    {
        this.Teachers = new List();
    }

    public int StandardId { get; set; }
    public string StandardName { get; set; }
    public string Description { get; set; }

    public virtual List Teachers { get; set; }
}

// Now lets do eager loaging using .Include() for Standard
using (var context = new DbContext())
{
    var stud1 = context.Students
                   .Include("Standard")
                   .Where(s => s.StudentName == "Shourabh")
                   .FirstOrDefault();
}
// No Lets do eager loading for teacher class

using (var context = new DbContext())
{
     var stud1 = context.Students.Include(s => s.Standard.Teachers)
                    .Where(s => s.StudentName == "Bill")
                    .FirstOrDefault();
}
Sachin Singh5y ago
go through
https://coding.abel.nu/2012/06/dont-use-linqs-join-navigate/