Associations are created with the Association method of the EntityConfiguration class.

The example of defining an association mapping configuration:

builder.Entity<Order>()
    .Association()
        .Name(@"Company_Order")
        .ToOne(order => order.Company).ThisKey(order => order.ShipCompanyID)
        .FromMany(company => company.Orders).OtherKey(company => company.CompanyID);

The following classes are used to help defining association mapping configuration. Reflection-based classes:

• AssociationStartConfiguration
• AssociationOneEndConfiguration
• AssociationManyEndConfiguration
• AssociationConfiguration
• ManyToManyAssociationConfiguration

Generic classes:

• AssociationStartConfiguration<TThisEntity>
• AssociationOneEndConfiguration<TThisEntity, TOtherEntity>
• AssociationManyEndConfiguration<TThisEntity, TOtherEntity>
• AssociationConfiguration<TOtherEntity>
• ManyToManyAssociationConfiguration<TOtherEntity>

Each of these classes performs its own part of configuring the association mapping. All of them are descendants of the AssociationBaseConfiguration class, which implements the IAssociationConfiguration interface.

AssociationStartConfiguration and AssociationStartConfiguration<TThisEntity>

The AssociationStartConfiguration class has the following public methods:

• Name - specifies the association name.
• ToOne and ToMany - configure navigation properties.

AssociationOneEndConfiguration, AssociationOneEndConfiguration<TThisEntity, TOtherEntity>, AssociationManyEndConfiguration, and AssociationManyEndConfiguration<TThisEntity, TOtherEntity>

The AssociationOneEndConfiguration and AssociationManyEndConfiguration classes have the following public methods:

• ThisKey - specifies the foreign key properties.
• ThisStorage - specifies non-public property or field for LinqConnect to work with instead of the navigation property. Usually it is used when the navigation property setter should perform some additional logics.
• FromParentOne, FromChildOne, and FromMany - specify the navigation property from the other end of the relationship. If you want to define a unidirectional association with no navigation property on the other side of the association, use the overloads of these methods with no parameters.

AssociationConfiguration and AssociationConfiguration<TOtherEntity>

The AssociationConfiguration class has the following public methods:

• Name - specifies the association name.
• OtherKey - specifies the association properties on the other end of the association.
• OtherStorage - specifies non-public property or field for LinqConnect to work with instead of the navigation property on the other end of the association.
• DeleteOnNull - specifies that if the navigation property of a dependent entityis set to NULL, this entity must be deleted from the database.
• DeleteRule(DeleteRule rule) - specifies the delete rule for the association.

ManyToManyAssociationConfiguration and ManyToManyAssociationConfiguration<TOtherEntity>

The ManyToManyAssociationConfiguration class has the following public methods:

• Name - specifies the association name.
• OtherKey - specifies the association properties on the other end of the association.
• OtherStorage - specifies non-public property or field for LinqConnect to work with instead of the navigation property on the other end of the association.
• LinkTableName - specifies the intermediate link table of the many-to-many association.
• LinkThisColumnNames - names of the foreign key columns from the foreign key, referencing the table of the entity, for which the Association() method was called.
• LinkOtherColumnNames - names of the foreign key columns from the foreign key, referencing the table of the other entity.