I can not create instace of DBContext - asp.net

Question

I have model:
public class Department
{
public int DepartmentID { get; set; }
[Required]
[UniqueDepartmentName]
public string Name { get; set; }
public List<Person> Persons { get; set; }
}
And DBcontext:
public class InstituteContext : DbContext
{
public InstituteContext (DbContextOptions<InstituteContext> options)
: base(options)
{
}
protected override void OnModelCreating(ModelBuilder modelBuilder)
{
modelBuilder.Entity<Department>().HasIndex(p => p.Name).IsUnique();
}
public DbSet<Institute.Models.Department> Department { get; set; }
}
As you see property "NAME" i make unique.
For validation i create My validation Attribute:
public class UniqueDepartmentName : ValidationAttribute
{
public override bool IsValid(object value)
{
var db = new InstituteContext();
}
}
But i can not create instance of InstituteContext, because constructor need parameters.
How i can create instance of InstituteContext? Or what should i pass to constructor in parameters?

Answer 1

Try this:
public class UniqueDepartmentName : ValidationAttribute
{
public override bool IsValid(object value)
{
var connectionString = "Your ConnectionString"
var options = new DbContextOptionsBuilder<InstituteContext>()
.UseSqlServer(new SqlConnection(connectionString)).Options;
using (var dbContext = new BloggingContext(options))
{
// Do necessary staffs here with dbContext
}
}
}

Answer 2

Your DbContextOptions method is in the wrong place, your constructor can be empty, and you need to add the method OnConfiguring, which receives the DbContextOptions.
Something like:
public DbSet<Department> Department { get; private set; }
protected override void OnConfiguring(DbContextOptionsBuilder options) {
// In my case I'm passing the connection string in this method below
options.UseSqlServer("Data Source=DATABASEIP;Initial Catalog=DATABASETABLE;" +
"User ID=USER;Password=PASSWORD");
}