/// <summary>
/// Translates the Expression tree to a tree of UpdateMembers
/// </summary>
/// <param name="expression">The expression.</param>
/// <returns></returns>
public UpdateMember GetUpdateMembers(Expression <Func <IUpdateConfiguration <T>, object> > expression)
{
var initialNode = new UpdateMember();
currentMember = initialNode;
Visit(expression);
return(initialNode);
}
protected override Expression VisitMethodCall(MethodCallExpression expression)
{
currentMethod = expression.Method.Name;
// go left to right in the subtree (ignore first argument for now)
for (int i = 1; i < expression.Arguments.Count; i++)
{
Visit(expression.Arguments[i]);
}
// go back up the tree and continue
currentMember = currentMember.Parent;
return(Visit(expression.Arguments[0]));
}
public static List <string> GetIncludeStrings(UpdateMember root)
{
var list = new List <string>();
if (root.Members.Count == 0)
{
list.Add(root.IncludeString);
}
foreach (var member in root.Members)
{
list.AddRange(GetIncludeStrings(member));
}
return(list);
}
protected override Expression VisitMember(MemberExpression expression)
{
// Create new node for this item
var newMember = new UpdateMember
{
Members = new Stack <UpdateMember>(),
Parent = currentMember,
Accessor = (PropertyInfo)expression.Member
};
currentMember.Members.Push(newMember);
previousMember = currentMember;
currentMember = newMember;
currentMember.IncludeString = previousMember.IncludeString != null
? previousMember.IncludeString + "." + currentMember.Accessor.Name
: currentMember.Accessor.Name;
// Chose if entity update or reference update and create expression
switch (currentMethod)
{
case "OwnedEntity":
currentMember.IsOwned = true;
break;
case "AssociatedEntity":
currentMember.IsOwned = false;
break;
case "OwnedCollection":
currentMember.IsOwned = true;
currentMember.IsCollection = true;
break;
case "AssociatedCollection":
currentMember.IsOwned = false;
currentMember.IsCollection = true;
break;
default:
throw new NotSupportedException("The method used in the update mapping is not supported");
}
return(base.VisitMember(expression));
}
/// <summary>
/// Updates a detached graph of entities by performing a diff comparison of object keys.
/// Author: Brent McKendrick
/// </summary>
/// <param name="context">The database context to attach / detach.</param>
/// <param name="dataStoreEntity">The entity (sub)graph as retrieved from the data store.</param>
/// <param name="updatingEntity">The entity (sub)graph after it has been updated</param>
private static void RecursiveGraphUpdate(DbContext context, object dataStoreEntity, object updatingEntity, UpdateMember member)
{
// Get item Type
var itemType = member.Accessor.PropertyType.IsGenericType
? member.Accessor.PropertyType.GetGenericArguments().First()
: member.Accessor.PropertyType;
// Create Helpful Linq Methods
Func <IEnumerable, IEnumerable> distinct = l => (IEnumerable)typeof(Enumerable).GetMethods().Single(m => m.Name.Equals("Distinct") && m.GetParameters().Count() == 1).MakeGenericMethod(new[] { itemType }).Invoke(null, new object[] { l });
Func <IEnumerable, IEnumerable> toList = l => (IEnumerable)typeof(Enumerable).GetMethod("ToList").MakeGenericMethod(new[] { itemType }).Invoke(null, new object[] { l });
Func <IEnumerable, object> singleOrDefault = l => typeof(Enumerable).GetMethods().Single(m => m.Name.Equals("SingleOrDefault") && m.GetParameters().Count() == 1).MakeGenericMethod(new[] { itemType }).Invoke(null, new object[] { l });
// Get member's navigation property
var memberNavProp = (member.Parent == null)
? member.IncludeString
: member.IncludeString.Substring((member.Parent.IncludeString ?? "").Length).TrimStart('.');
if (member.IsCollection)
{
// We are dealing with a collection
// Get distinctly the new itens
var updateValues = (IEnumerable)member.Accessor.GetValue(updatingEntity, null);
updateValues = updateValues != null?toList(distinct(updateValues)) : new List <object>();
// Get database values
IEnumerable dbCollection;
var actualEntityIsOnTheContext = updatingEntity == dataStoreEntity;
if (actualEntityIsOnTheContext && context.Entry(updatingEntity).State != EntityState.Added)
{
dbCollection = member.IsOwned
? toList(context.Entry(updatingEntity).Collection(memberNavProp).Query())
: toList(((ObjectQuery)context.Entry(updatingEntity).Collection(memberNavProp).Query()).Execute(MergeOption.OverwriteChanges));
// Assure the entity's child collection wasn't refreshed when getting db values.
member.Accessor.SetValue(updatingEntity, updateValues, null);
}
else
{
dbCollection = (IEnumerable)member.Accessor.GetValue(dataStoreEntity, null);
}
Type dbCollectionType = dbCollection.GetType();
Type innerElementType;
if (dbCollectionType.IsArray)
{
innerElementType = dbCollectionType.GetElementType();
}
else if (dbCollectionType.IsGenericType)
{
innerElementType = dbCollectionType.GetGenericArguments()[0];
}
else
{
throw new InvalidOperationException("GraphDiff required the collection to be either IEnumerable<T> or T[]");
}
var keyFields = context.GetKeysFor(innerElementType);
var dbHash = MapCollectionToDictionary(keyFields, dbCollection);
// Iterate through the elements from the updated graph and try to match them against the db graph.
List <object> additions = new List <object>();
foreach (object updateItem in updateValues)
{
var key = CreateHash(keyFields, updateItem);
// try to find in db collection
object dbItem;
if (dbHash.TryGetValue(key, out dbItem))
{
// If we own the collection
if (member.IsOwned)
{
context.Entry(dbItem).CurrentValues.SetValues(updateItem); // match means we are updating
AttachCyclicNavigationProperty(context, dataStoreEntity, updateItem);
foreach (var childMember in member.Members)
{
RecursiveGraphUpdate(context, dbHash[key], updateItem, childMember);
}
}
dbHash.Remove(key); // remove to leave only db removals in the collection
}
else
{
additions.Add(updateItem);
}
}
// Removal of dbItem's left in the collection
foreach (var dbItem in dbHash.Values)
{
// Removing dbItem, assure it's children will me deleted.
foreach (var subMember in member.Members)
{
RecursiveGraphUpdate(context, dbItem, dbItem, subMember);
}
// Own the collection so remove it completely.
if (member.IsOwned)
{
context.Set(ObjectContext.GetObjectType(dbItem.GetType())).Remove(dbItem);
}
dbCollection.GetType().GetMethod("Remove").Invoke(dbCollection, new[] { dbItem });
}
// Add elements marked for addition
foreach (object newItem in additions)
{
if (!member.IsOwned)
{
context.Set(ObjectContext.GetObjectType(newItem.GetType())).Attach(newItem);
if (GraphDiffConfiguration.ReloadAssociatedEntitiesWhenAttached)
{
context.Entry(newItem).Reload();
}
}
// Otherwise we will add to object
dbCollection.GetType().GetMethod("Add").Invoke(dbCollection, new[] { newItem });
AttachCyclicNavigationProperty(context, dataStoreEntity, newItem);
}
}
else // not collection
{
var actualEntityIsOnTheContext = updatingEntity == dataStoreEntity;
var dbvalue = (actualEntityIsOnTheContext && context.Entry(dataStoreEntity).State != EntityState.Added)// && member.IsOwned)
? singleOrDefault(context.Entry(updatingEntity).Reference(memberNavProp).Query())
: member.Accessor.GetValue(dataStoreEntity, null);
var newvalue = member.Accessor.GetValue(updatingEntity, null);
if (dbvalue == null && newvalue == null) // No value
{
return;
}
// If we own the collection then we need to update the entities otherwise simple relationship update
if (!member.IsOwned)
{
if (dbvalue != null)
{
// sets the state of the associated entity as unchanged.
// I need reload the dbValue to undo the changes made in it
// (except when it is added state; in this case, we will add it).
if (context.Entry(dbvalue).State != EntityState.Added)
{
context.Entry(dbvalue).Reload();
}
context.Entry(dbvalue).State = EntityState.Unchanged;
}
if (newvalue == null)
{
member.Accessor.SetValue(dataStoreEntity, null, null);
return;
}
if (dbvalue != null && newvalue != null)
{
var keyFields = context.GetKeysFor(ObjectContext.GetObjectType(newvalue.GetType()));
var newKey = CreateHash(keyFields, newvalue);
var updateKey = CreateHash(keyFields, dbvalue);
if (newKey == updateKey)
{
return; // do nothing if the same key
}
}
if (context.Entry(newvalue).State == EntityState.Detached)
{
context.Set(ObjectContext.GetObjectType(newvalue.GetType())).Attach(newvalue);
}
member.Accessor.SetValue(dataStoreEntity, newvalue, null);
context.Entry(newvalue).State = EntityState.Unchanged;
//if (GraphDiffConfiguration.ReloadAssociatedEntitiesWhenAttached)
context.Entry(newvalue).Reload();
}
else
{
if (dbvalue != null && newvalue != null)
{
// Check if the same key, if so then update values on the entity
var keyFields = context.GetKeysFor(ObjectContext.GetObjectType(newvalue.GetType()));
var newKey = CreateHash(keyFields, newvalue);
var updateKey = CreateHash(keyFields, dbvalue);
// perform update if the same
if (updateKey == newKey)
{
context.Entry(dbvalue).CurrentValues.SetValues(newvalue);
}
else
{
member.Accessor.SetValue(dataStoreEntity, newvalue, null);
}
}
else
{
member.Accessor.SetValue(dataStoreEntity, newvalue, null);
}
AttachCyclicNavigationProperty(context, dataStoreEntity, newvalue);
// TODO
foreach (var childMember in member.Members)
{
RecursiveGraphUpdate(context, dbvalue, newvalue, childMember);
}
}
}
}
