/// <summary>
/// this method needs to be handled with much care.
/// First, the input list must not stem from a request finishing with a call to AsNoTracking method.
/// Second, the query from which the input stems must be closed properly.
/// This means that the result of a query must be cast to any kind of IEnumerable (List, Array)
/// which will close the preceding query.
/// </summary>
/// <param name="dbAccess"></param>
/// <param name="entities"></param>
/// <returns></returns>
public static DbResults <T> Delete <T, TId>(this DbContext dbAccess, IEnumerable <T> entities)
where T : BaseAuditable <TId>
{
var results = new DbResults <T>();
if (null != entities)
{
using var transaction = dbAccess.Database.BeginTransaction();
foreach (var entity in entities)
{
var result = new DbResult <T> {
Entity = entity
};
if (null == entity)
{
result.ResultCode = DbResultCode.EntityIsNull;
continue;
}
// Check 1: model has no unique key - skip
if (EqualityComparer <TId> .Default.Equals(entity.Id, default))
{
result.ResultCode = DbResultCode.Impractical;
continue;
}
// Check 2: model can be deleted
dbAccess.Entry(entity).State = EntityState.Deleted;
var changes = dbAccess.SaveChanges();
if (0 == changes || dbAccess.Entry(entity).State != EntityState.Detached)
{
result.ResultCode = DbResultCode.SaveFailed;
}
results.Results.Add(result);
}
if (results.Success)
{
transaction.Commit();
}
else
{
transaction.Rollback();
}
}
return(results);
}
public static void ValidateEntity <T, TId>(T entity, DbResult <T> result)
where T : IAuditable <TId>
{
entity.CreatedAt = EqualityComparer <DateTime> .Default.Equals(entity.CreatedAt, default)
? DateTime.UtcNow
: entity.CreatedAt;
entity.CreatedBy ??= Requestor;
var validationContext = new ValidationContext(entity);
if (!Validator.TryValidateObject(entity, validationContext, result.ValidationResults, true))
{
result.ResultCode |= DbResultCode.ValidationFailed;
}
}
public static DbResult <T> CheckUpdateEntity <T, TId>(this DbContext dbContext, T entity)
where T : BaseAuditable <TId>
{
var result = new DbResult <T> {
Entity = entity
};
// Check 0: entity is NULL
if (null == entity)
{
result.ResultCode = DbResultCode.EntityIsNull;
return(result);
}
// Check 1: entity has no unique key - skip
if (EqualityComparer <TId> .Default.Equals(entity.Id, default))
{
result.ResultCode |= DbResultCode.Impractical;
}
// Check 2: entity does not pass validation - skip
ValidateEntity <T, TId>(entity, result);
// Check 3: entity violates UK constraint - skip
if (entity is IUniqueAuditable uniqueEntity)
{
var baseAuditables = dbContext.Set <T>().AsEnumerable() ?? new List <T>();
if (baseAuditables.Any(q => uniqueEntity.HasSameUniqueKey(q) &&
!EqualityComparer <TId> .Default.Equals(entity.Id, q.Id)))
{
result.ResultCode |= DbResultCode.Duplicate;
}
}
return(result);
}