/// <summary>
/// Update a single child navigation property on a parent entity specified by T and parentId.
/// Expects to be passed a complete list of child entities for the targeted navigation property.
/// This method will update the database such that the navigation property for the parent contains the exact list of children passed to this method.
/// </summary>
/// <typeparam name="T">The parent entity type</typeparam>
/// <typeparam name="I">The type of the id property</typeparam>
/// <typeparam name="C">The type of the child navigation property being targeted for updates.</typeparam>
/// <param name="context"></param>
/// <param name="childNavigation"></param>
/// <param name="parentId"></param>
/// <param name="children"></param>
public static void UpdateChild <T, I, C>(this PimsContext context, Expression <Func <T, object> > childNavigation, I parentId, C[] children) where T : IdentityBaseAppEntity <I> where C : IdentityBaseAppEntity <I>
{
var dbEntity = context.Find <T>(parentId);
var dbEntry = context.Entry(dbEntity);
var propertyName = childNavigation.GetPropertyAccess().Name;
var dbItemsEntry = dbEntry.Collection(propertyName);
var accessor = dbItemsEntry.Metadata.GetCollectionAccessor();
dbItemsEntry.Load();
var dbItemsMap = dbItemsEntry.CurrentValue.Cast <IdentityBaseAppEntity <I> >()
.ToDictionary(e => e.Id);
foreach (var item in children)
{
if (!dbItemsMap.TryGetValue(item.Id, out var oldItem))
{
accessor.Add(dbEntity, item, false);
}
else
{
context.Entry(oldItem).CurrentValues.SetValues(item);
dbItemsMap.Remove(item.Id);
}
}
foreach (var oldItem in dbItemsMap.Values)
{
accessor.Remove(dbEntity, oldItem);
context.Remove(oldItem);
}
}
/// <summary>
/// Update a single grandchild navigation property on a parent entity specified by T and parentId.
/// Expects to be passed a complete list of child and grandchild entities for the targeted navigation property.
/// This method will update the database such that the navigation property for the parent contains the exact list of children and grandchildren passed to this method.
/// </summary>
/// <typeparam name="T">The parent entity type</typeparam>
/// <typeparam name="I">The type of the id property</typeparam>
/// <typeparam name="C">The type of the child navigation property being targeted for updates.</typeparam>
/// <param name="context"></param>
/// <param name="childNavigation"></param>
/// <param name="grandchildNavigation"></param>
/// <param name="parentId"></param>
/// <param name="childrenWithGrandchildren">The collection of children (and grandchildren) to update. Assumes grandchildren can be accessed via grandchildNavigation</param>
/// <param name="canDeleteGrandchild">A callback to determine whether is safe to remove a grandchild entity</param>
public static void UpdateGrandchild <T, I, C>(
this PimsContext context,
Expression <Func <T, object> > childNavigation,
Expression <Func <C, object> > grandchildNavigation,
I parentId,
C[] childrenWithGrandchildren,
Func <PimsContext, C, bool> canDeleteGrandchild) where T : IdentityBaseAppEntity <I> where C : IdentityBaseAppEntity <I>
{
var dbEntity = context.Find <T>(parentId);
var dbEntry = context.Entry(dbEntity);
var childPropertyName = childNavigation.GetPropertyAccess().Name;
var childCollection = dbEntry.Collection(childPropertyName);
var childAccessor = childCollection.Metadata.GetCollectionAccessor();
childCollection.Load();
var existingChildren = childCollection.CurrentValue.Cast <IdentityBaseAppEntity <I> >().ToDictionary(e => e.Id);
// Compile the grandchildNavigation lambda expression so we can extract the value from the passed in array of children
var grandchildPropertyName = grandchildNavigation.GetPropertyAccess().Name;
var grandchildFunc = grandchildNavigation.Compile();
foreach (var child in childrenWithGrandchildren)
{
if (!existingChildren.TryGetValue(child.Id, out var existingChild))
{
childAccessor.Add(dbEntity, child, false);
}
else
{
var dbChildEntry = context.Entry(existingChild);
dbChildEntry.CurrentValues.SetValues(child);
// load grandchild navigation property
var grandchildReference = dbChildEntry.Reference(grandchildPropertyName);
grandchildReference.Load();
// Update grandchild navigation with values passed in the array
var grandchildValue = grandchildFunc(child);
grandchildReference.TargetEntry.CurrentValues.SetValues(grandchildValue);
existingChildren.Remove(child.Id);
}
}
foreach (var existingChild in existingChildren.Values)
{
var dbChildEntry = context.Entry(existingChild);
childAccessor.Remove(dbEntity, existingChild);
context.Remove(existingChild);
// Also remove the grandchild referenced by the child being removed
if (canDeleteGrandchild(context, existingChild as C))
{
// load grandchild navigation property
var grandchildReference = dbChildEntry.Reference(grandchildPropertyName);
grandchildReference.Load();
var dbGrandchild = grandchildReference.TargetEntry?.Entity;
if (dbGrandchild != null)
{
context.Remove(dbGrandchild);
}
}
}
}