/// <summary>
/// Attempt to insert an entity, leaving any exceptions go
/// </summary>
private void AttemptInsert(string type, Entity entity)
{
JsonObject document = SerializeEntity(entity);
// make sure _key and _rev are not even present
// (they will be set automatically to null, but arango
// requires them to not be present at all - null is not enough)
document.Remove("_key");
document.Remove("_rev");
// set timestamps
// (serializer instead of direct setting, because the serializer
// does not store "Z" (timezone), so deserialization does not
// correct for timezones and loads it as it is)
DateTime now = DateTime.UtcNow;
document["CreatedAt"] = Serializer.ToJson(now);
document["UpdatedAt"] = Serializer.ToJson(now);
var newAttributes = arango.ExecuteAqlQuery(new AqlQuery()
.Insert(document).Into(EntityUtils.CollectionFromType(type))
.Return("NEW")
).First().AsJsonObject;
// update entity attributes
EntitySerializer.SetAttributes(
entity,
newAttributes,
DeserializationContext.ServerStorageToServer
);
}
/// <summary>
/// Updates the entity in the database and returns the updated entity
/// Careful insert checks revisions to detect write-write conflicts
/// </summary>
public virtual void Update(
Entity entity,
bool carefully = false
)
{
string type = EntityUtils.GetEntityStringType(entity.GetType());
if (string.IsNullOrEmpty(entity.EntityKey))
{
throw new ArgumentException(
"Provided entity has not been inserted yet"
);
}
try
{
JsonObject oldDocument = FindDocument(entity.EntityId);
if (oldDocument == null)
{
throw new ArangoException(404, 1202, "document not found");
}
JsonObject newDocument = SerializeEntity(entity);
// set timestamps
// (serializer instead of direct setting, because the serializer
// does not store "Z" (timezone), so deserialization does not
// correct for timezones and loads it as it is)
newDocument["CreatedAt"] = oldDocument["CreatedAt"];
newDocument["UpdatedAt"] = Serializer.ToJson(DateTime.UtcNow);
// if we aren't careful, then don't even send the _rev key
// (just to make sure the database won't throw a conflict)
// (this probably doesn't help with anything, but why not do it)
if (!carefully)
{
newDocument.Remove("_rev");
}
var newAttributes = arango.ExecuteAqlQuery(new AqlQuery()
.Replace(() => newDocument)
.CheckRevs(carefully)
.In(EntityUtils.CollectionFromType(type))
.Return("NEW")
).First().AsJsonObject;
EntitySerializer.SetAttributes(
entity,
newAttributes,
DeserializationContext.ServerStorageToServer
);
}
catch (ArangoException e) when(e.ErrorNumber == 1200)
{
// write-write conflict
/*
* Write-write conflict (1200) can be thrown even when we
* don't explicitly check for revisions. This comes down
* to the way ArangoDB works. If it tries to acquire a write
* lock on a document and fails, it doesn't retry and throws
* the conflict error (it fails because someone else is
* currently writing to that document). Giving up on the write
* is ok in this situation as it could be though of as the
* other process immediately overwriting our update.
*
* https://github.com/arangodb/arangodb/issues/9702
*/
// When we are careful, we need to notify the user by
// throwing a conflict exception
if (carefully)
{
throw new EntityRevConflictException(
"Entity has been modified since the last refresh"
);
}
// When we aren't careful, we just warn the user and
// ignore the fact the write failed. (see the note above)
log.Warning(
"Entity wasn't saved due to a write-write conflict " +
"(other process was saving the same entity at the " +
"same time).\nCheck out documentation for the method " +
"entity.SaveCarefully() to learn more.",
e
);
}
catch (ArangoException e) when(e.ErrorNumber == 1202)
{
// document not found
throw new EntityPersistenceException(
"Entity has not yet been inserted, or already deleted"
);
}
catch (ArangoException e) when(e.ErrorNumber == 1203)
{
// collection not found
throw new EntityPersistenceException(
"Entity has not yet been inserted, or already deleted"
);
}
}