Annotations

Annotations provide metadata about your objects that allows DbExtensions generate commands for you. There are four attributes available for this purpose: TableAttribute, ColumnAttribute, AssociationAttribute and ComplexPropertyAttribute. The use of these attributes is always required, DbExtensions doesn’t infer any mapping between your objects and your database (no conventions).

TableAttribute

Use the TableAttribute to associate a class with a database table. If no name is specified, the class name is used as table name.

[Table(Name = "Products")]
public class Product {
  ...
}

ColumnAttribute

Use the ColumnAttribute to associate a property with a column in a database table. If no name is specified, the property name is used as column name.

[Column(IsPrimaryKey = true, IsDbGenerated = true)]
public int ProductID { get; set; }

AssociationAttribute

Use the AssociationAttribute to represent a database association, such as a foreign key relationship.

[Association(ThisKey = nameof(CategoryID))]
public Category Category { get; set; }

For one-to-many relationships, use a type that implements IEnumerable<T>, such as Collection<T>.

[Association(OtherKey = nameof(OrderDetail.ProductID))]
public Collection<OrderDetail> OrderDetails { get; } = new Collection<OrderDetail>();

The default for ThisKey and OtherKey, when not specified, is the type’s primary key properties.

For multi-column keys use a comma-separated list.

ComplexPropertyAttribute

Use the ComplexPropertyAttribute (starting v6.3) to group columns into a separate type. Some ORMs call these objects value objects. If no name is specified, the property name is used as base name, which is prepended to the column names as defined in the complex type.

[Table(Name = "Customers")]
public class Customer {

  [Column(IsPrimaryKey = true)]
  public string CustomerID { get; set; }

  [Column]
  public string CompanyName { get; set; }

  [ComplexProperty]
  public Contact Contact { get; set; }
}

public class Contact {

  [Column]
  public string Name { get; set; }

  [Column]
  public string Title { get; set; }
}

Use the Separator property if the columns names use a naming convention that separate words, e.g. if the column names are Contact_Name and Contact_Title:

[ComplexProperty(Separator = "_")]
public Contact Contact { get; set; }