Entity Framework Code First DataAnnotations [Key] attribute
Example
Key is a field in a table which uniquely identifies each row/record in a database table.
Use this attribute to override the default Code-First convention. If applied to a property, it will be used as the primary key column for this class.
using System.ComponentModel.DataAnnotations;
public class Person
{
[Key]
public int PersonKey { get; set; } // <- will be used as primary key
public string PersonName { get; set; }
}
If a composite primary key is required, the [Key] attribute can also be added to multiple properties. The order of the columns within the composite key must be provided in the form [Key, Column(Order = x)].
using System.ComponentModel.DataAnnotations;
public class Person
{
[Key, Column(Order = 0)]
public int PersonKey1 { get; set; } // <- will be used as part of the primary key
[Key, Column(Order = 1)]
public int PersonKey2 { get; set; } // <- will be used as part of the primary key
public string PersonName { get; set; }
}
Without the [Key] attribute, EntityFramework will fall back to the default convention which is to use the property of the class as a primary key that is named "Id" or "{ClassName}Id".
public class Person
{
public int PersonID { get; set; } // <- will be used as primary key
public string PersonName { get; set; }
}
