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copied!<p>Answering my own question in <strong>Part 2</strong>:</p> <p>Here is my approach to checking for related dependents when deleting an entity on the principal end of a many-to-one relationship and where dependents are NOT exposed as a navigation collection in the principal (e.g. class <code>Address</code> has a <code>Country</code> property, but class <code>Country</code> doesn't have an <code>Addresses</code> collection).</p> <p><em>DbContext</em></p> <p>Add the following method to the context class:</p> <pre><code>/// <summary> /// Returns an array of entities tracked by the /// context that satisfy the filter criteria. /// </summary> public DbEntityEntry[] GetTrackedEntities<T>( Expression<Func<DbEntityEntry<T>, bool>> filterCriteria) where T : class { var result = new List<DbEntityEntry>(); var doesItMatch = filterCriteria.Compile(); foreach (var entry in this.ChangeTracker.Entries<T>()) { if (doesItMatch(entry)) result.Add(entry); } return result.ToArray(); } </code></pre> <p><em>Repositories</em></p> <p>Create a repository for each class that has some dependencies, override the <code>Delete</code> method and use the new <code>GetTrackedEntities<T></code> method to get all related dependents and either:</p> <ul> <li>explicitly delete them if they are cascade-deletable in code</li> <li>detach them from the context if they are cascade-deletable in the DB itself</li> <li>throw an exception if they are NOT cascade-deletable. </li> </ul> <p>Example of the latter case:</p> <pre><code>public class EFCountryRepository : EFReadWriteRepository<Country, string>, ICountryRepository { public override void Delete(Country instance) { // Allow the Country to be deleted only if there are no dependent entities // currently in the context that are NOT cascade-deletable. if ( // are there any Regions in the context that belong to this Country? _dbContext.GetTrackedEntities<Region>(e => e.Entity.CountryID == instance.ID || e.Entity.Country == instance).Length > 0 || // are there any Addresses in the context that belong to this Country? _dbContext.GetTrackedEntities<Address>(e => e.Entity.CountryID == instance.ID || e.Entity.Country == instance).Length > 0 ) throw new Exception(String.Format( "Country '{0}' is in use and cannot be deleted.", instance.ID)); base.Delete(instance); } // ... other methods ... } </code></pre> <p>Example of a case where cascade-deleting will be done by the DB itself, so all we need to do is detach the dependents from the context:</p> <pre><code>public class EFOrderRepository : EFReadWriteRepository<Order, string>, IOrderRepository { public override void Delete(Order instance) { foreach (var orderItem in _dbContext.GetTrackedEntities<OrderItem>(e => e.Entity.OrderID == instance.ID || e.Entity.Order == instance)) { _dbContext.Entry(orderItem).State = System.Data.EntityState.Detached; } base.Delete(instance); } // ... other methods ... } </code></pre> <p>Hope someone will find this solution helpful.</p>

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