/// <summary>
/// Adds or updates an entity in the database from a ViewModel, only if a certain condition is satisfied. The Entity class needs to implement IPersistableObj interface.
/// </summary>
/// <typeparam name="TViewModel">View model type</typeparam>
/// <typeparam name="TDbSet">Base entity type (i.e DbSet type)</typeparam>
/// <typeparam name="TEntity">Entity type</typeparam>
/// <param name="set">Entity data set (e.g. Context.Drills)</param>
/// <param name="viewModel">View model instance</param>
/// <param name="filter">Condition to be satisfied [e.g (UserDrill d) => d.AccountId == 5]</param>
/// <param name="key">Entity key value</param>
/// <param name="includes">Includes needed to map the entity to the view model type.</param>
/// <returns>The saved entity mapped to the view model type or null if the condition is not satisfied.</returns>
public static TViewModel SaveIfAllowed <TViewModel, TDbSet, TEntity>(this DbContext context, TViewModel viewModel, Expression <Func <TEntity, bool> > filter, object[] keyValues, Func <IQueryable <TEntity>, IQueryable <TEntity> > includes = null)
where TDbSet : class
where TEntity : class, TDbSet, new()
{
var set = context.Set <TDbSet>();
keyValues = keyValues ?? ArrayExtensions.EmptyArray <object>();
var metadata = PrimaryKeysMetadataFactory <TEntity> .GetForContext(context);
var entity = keyValues.Length > 0 ? set.OfType <TEntity>().Where(metadata.GetKeysFilter(keyValues))
.ApplyIncludes(includes)
.FirstOrDefault()
: null;
if (entity == null)
{
using (var tr = new TransactionScope(TransactionScopeOption.Required, new TransactionOptions()
{
IsolationLevel = IsolationLevel.ReadCommitted
}, TransactionScopeAsyncFlowOption.Enabled))
{
entity = set.Create <TEntity>();
Mapper.Map(viewModel, entity);
set.Add(entity);
context.SaveChanges();
var newKeys = metadata.GetPrimaryKeys(entity);
//apply filter on newly added entity.
var savedData = set.OfType <TEntity>().Where(metadata.GetKeysFilter(newKeys)).Where(filter)
.ApplyIncludes(includes)
.FirstOrDefault();
if (savedData == null)
{
return(default(TViewModel));
}
tr.Complete();
}
}
else
{
var allowed = set.OfType <TEntity>().Where(metadata.GetKeysFilter(keyValues)).Where(filter).Any();
if (!allowed)
{
return(default(TViewModel));
}
Mapper.Map(viewModel, entity);
context.SaveChanges();
}
// map back to viewModel (to get any identity column inserted ID)
Mapper.Map(entity, viewModel);
return(viewModel);
}
public static object[] GetPrimaryKeys <TEntity>(this DbContext context, TEntity entity) where TEntity : class
{
if (entity == null)
{
return(ArrayExtensions.EmptyArray <object>());
}
var metadata = PrimaryKeysMetadataFactory <TEntity> .GetForContext(context);
return(metadata.GetPrimaryKeys(entity));
}
public static Expression <Func <TEntity, bool> > GetPrimaryKeysFilter <TEntity>(this DbContext context, object[] keyValues) where TEntity : class
{
var metadata = PrimaryKeysMetadataFactory <TEntity> .GetForContext(context);
return(metadata.GetKeysFilter(keyValues));
}