/// <inheritdoc />
public IReadOnlyList <Resource> SaveReferences(IUnitOfWork uow, Resource instance, ResourceEntity entity)
{
var context = new ReferenceSaverContext(uow, Graph, instance, entity);
SaveReferences(context, instance);
return(context.EntityCache.Keys.Where(i => i.Id == 0).ToList());
}
/// <summary>
/// Create a <see cref="ResourceRelation"/> entity for a property match
/// </summary>
private static ResourceRelation CreateRelationForProperty(ReferenceSaverContext context, IResourceRelationRepository relationRepo, ResourceReferenceAttribute att)
{
var relationType = att.RelationType;
var relEntity = relationRepo.Create((int)relationType);
context.CreatedRelations.Add(relEntity);
return(relEntity);
}
/// <inheritdoc />
public IReadOnlyList <Resource> SaveRoots(IUnitOfWork uow, IReadOnlyList <Resource> instances)
{
var context = new ReferenceSaverContext(uow, Graph);
foreach (var instance in instances)
{
SaveReferences(context, instance);
}
return(context.EntityCache.Keys.ToArray());
}
/// <inheritdoc />
public IReadOnlyList <Resource> SaveSingleCollection(IUnitOfWork uow, Resource instance, PropertyInfo property)
{
var entity = uow.GetEntity <ResourceEntity>(instance);
var relations = ResourceRelationAccessor.FromEntity(uow, entity);
var context = new ReferenceSaverContext(uow, Graph, instance, entity);
var matches = MatchingRelations(relations, property);
var typeMatches = TypeFilter(matches, property, context.ResolveReference).ToList();
var created = UpdateCollectionReference(context, entity, instance, property, typeMatches);
foreach (var resource in created)
{
SaveReferences(context, resource);
}
return(context.EntityCache.Keys.Where(i => i.Id == 0).ToList());
}
/// <summary>
/// Make sure our resource-relation graph in the database is synced to the resource object graph. This method
/// updates a collection of references
/// </summary>
/// <example>
/// [ResourceReference(ResourceRelationType.TransportRoute, ResourceReferenceRole.Source)]
/// public IReferences<Resource> FriendResources { get; set; }
/// </example>
private IEnumerable <Resource> UpdateCollectionReference(ReferenceSaverContext context, ResourceEntity entity, Resource resource, PropertyInfo referenceProperty, IReadOnlyList <ResourceRelationAccessor> relationTemplates)
{
var relationRepo = context.UnitOfWork.GetRepository <IResourceRelationRepository>();
var referenceAtt = referenceProperty.GetCustomAttribute <ResourceReferenceAttribute>();
// Get the value stored in the reference property
var propertyValue = referenceProperty.GetValue(resource);
var referencedResources = ((IEnumerable <IResource>)propertyValue).Cast <Resource>().ToList();
// Check required attribute against empty collections
if (referencedResources.Count == 0 && referenceAtt.IsRequired)
{
throw new ValidationException($"Property {referenceProperty.Name} is flagged 'Required' and was empty!");
}
// First delete references that are not used by ANY property of the same configuration
var currentReferences = CurrentReferences(resource, referenceAtt);
var deleted = relationTemplates.Where(m => currentReferences.All(cr => cr != context.ResolveReference(m))).ToList();
foreach (var relation in deleted)
{
ClearOnTarget(context.ResolveReference(relation), resource, referenceAtt);
relationRepo.Remove(relation.Entity);
}
// Now create new relations
var created = referencedResources.Where(rr => relationTemplates.All(m => rr != context.ResolveReference(m))).ToList();
foreach (var createdReference in created)
{
SetOnTarget(createdReference, resource, referenceAtt);
var relEntity = CreateRelationForProperty(context, relationRepo, referenceAtt);
var referencedEntity = GetOrCreateEntity(context, createdReference);
UpdateRelationEntity(entity, referencedEntity, relEntity, referenceAtt);
}
return(created.Where(cr => cr.Id == 0));
}
/// <summary>
/// Get or create an entity for a resource instance
/// </summary>
private static ResourceEntity GetOrCreateEntity(ReferenceSaverContext context, Resource instance)
{
// First check if the context contains an entity for the instance
if (context.EntityCache.ContainsKey(instance))
{
return(context.EntityCache[instance]);
}
ResourceEntity entity;
if (instance.Id > 0)
{
entity = context.UnitOfWork.GetEntity <ResourceEntity>(instance);
}
else
{
entity = ResourceEntityAccessor.SaveToEntity(context.UnitOfWork, instance);
context.ResourceLookup[entity] = instance;
}
// Get or create an entity for the instance
return(context.EntityCache[instance] = entity);
}
private void SaveReferences(ReferenceSaverContext context, Resource instance)
{
var entity = GetOrCreateEntity(context, instance);
var relations = ResourceRelationAccessor.FromEntity(context.UnitOfWork, entity)
.Union(ResourceRelationAccessor.FromQueryable(context.CreatedRelations.AsQueryable(), entity))
.ToList();
var createdResources = new List <Resource>();
foreach (var referenceProperty in ReferenceProperties(instance.GetType(), false))
{
var matches = MatchingRelations(relations, referenceProperty);
var typeMatches = TypeFilter(matches, referenceProperty, context.ResolveReference).ToList();
if (typeof(IEnumerable <IResource>).IsAssignableFrom(referenceProperty.PropertyType))
{
// Save a collection reference
var created = UpdateCollectionReference(context, entity, instance, referenceProperty, typeMatches);
createdResources.AddRange(created);
}
else
{
// Save a single reference
var createdResource = UpdateSingleReference(context, entity, instance, referenceProperty, typeMatches);
if (createdResource != null)
{
createdResources.Add(createdResource);
}
}
}
// Recursively save references for new resources
foreach (var resource in createdResources)
{
SaveReferences(context, resource);
}
}
/// <summary>
/// Make sure our resource-relation graph in the database is synced to the resource object graph. This method
/// updates single references like in the example below
/// </summary>
/// <example>
/// [ResourceReference(ResourceRelationType.TransportRoute, ResourceReferenceRole.Source)]
/// public Resource FriendResource { get; set; }
/// </example>
private Resource UpdateSingleReference(ReferenceSaverContext context, ResourceEntity entity, Resource resource, PropertyInfo referenceProperty, IReadOnlyList <ResourceRelationAccessor> matches)
{
var relationRepo = context.UnitOfWork.GetRepository <IResourceRelationRepository>();
var value = referenceProperty.GetValue(resource);
var referencedResource = value as Resource;
// Validate if object assigned to the property is a resource
if (value != null && referencedResource == null)
{
throw new ArgumentException($"Value of property {referenceProperty.Name} on resource {resource.Id}:{resource.GetType().Name} must be a Resource");
}
var referenceAtt = referenceProperty.GetCustomAttribute <ResourceReferenceAttribute>();
// Validate if required property is set
if (referencedResource == null && referenceAtt.IsRequired)
{
throw new ValidationException($"Property {referenceProperty.Name} is flagged 'Required' and was null!");
}
// Check if there is a relation that represents this reference
if (referencedResource != null && matches.Any(m => referencedResource == context.ResolveReference(m)))
{
return(null);
}
// Get all references of this resource with the same relation information
var currentReferences = CurrentReferences(resource, referenceAtt);
// Try to find a match that is not used in any reference
var relMatch = (from match in matches
where currentReferences.All(cr => cr != context.ResolveReference(match))
select match).FirstOrDefault();
var relEntity = relMatch?.Entity;
if (relEntity == null && referencedResource != null)
{
// Create a new relation
relEntity = CreateRelationForProperty(context, relationRepo, referenceAtt);
SetOnTarget(referencedResource, resource, referenceAtt);
}
else if (relEntity != null && referencedResource == null)
{
// Delete a relation, that no longer exists
ClearOnTarget(context.ResolveReference(relMatch), resource, referenceAtt);
relationRepo.Remove(relEntity);
return(null);
}
// ReSharper disable once ConditionIsAlwaysTrueOrFalse <<- To identify the remaining case
else if (relEntity == null && referencedResource == null)
{
// Relation did not exist before and still does not
return(null);
}
// Relation was updated, make sure the backlinks match
else
{
ClearOnTarget(context.ResolveReference(relMatch), resource, referenceAtt);
SetOnTarget(referencedResource, resource, referenceAtt);
}
// Set source and target of the relation depending on the reference roles
var referencedEntity = GetOrCreateEntity(context, referencedResource);
UpdateRelationEntity(entity, referencedEntity, relEntity, referenceAtt);
// Return referenced resource if it is new
return(referencedResource.Id == 0 ? referencedResource : null);
}
