/// <summary>
/// Load a reference collection from the database.
/// </summary>
/// <typeparam name="TSource">The type of the value.</typeparam>
/// <typeparam name="TProperty">The type of the reference collection.</typeparam>
/// <param name="observable">The parent observable.</param>
/// <param name="propertyExpression">The property selection expression.</param>
/// <returns>An instance of <see cref="IProviderObservable{TSource}"/>.</returns>
public static IProviderObservable <TSource> LoadCollection <TSource, TProperty>(
this IProviderObservable <TSource> observable,
Expression <Func <TSource, IEnumerable <TProperty> > > propertyExpression)
where TSource : class
where TProperty : class =>
observable.WithEntityEntryAsync(
async s => await s.Collection(propertyExpression).LoadAsync());
/// <summary>
/// Load a single reference from the database.
/// </summary>
/// <typeparam name="TSource">The type of the value.</typeparam>
/// <typeparam name="TProperty">The type of the reference.</typeparam>
/// <param name="observable">The parent observable.</param>
/// <param name="propertyExpression">The property selection expression.</param>
/// <returns>An instance of <see cref="IProviderObservable{TSource}"/>.</returns>
public static IProviderObservable <TSource> LoadReference <TSource, TProperty>(
this IProviderObservable <TSource> observable,
Expression <Func <TSource, TProperty> > propertyExpression)
where TSource : class
where TProperty : class =>
observable.WithEntityEntryAsync(
async s => await s.Reference(propertyExpression).LoadAsync());
/// <summary>
/// <para>
/// Reloads the entity from the database overwriting any property
/// values with values from the database.
/// </para>
/// <para>
/// The entity will be in the
/// <see cref="F:Microsoft.EntityFrameworkCore.EntityState.Unchanged" /> state
/// after calling this method, unless the entity does not exist in the database,
/// in which case the entity will be
/// <see cref="F:Microsoft.EntityFrameworkCore.EntityState.Detached" />. Finally,
/// calling Reload on an <see cref="F:Microsoft.EntityFrameworkCore.EntityState.Added" />
/// entity that does not exist in the database is a no-op. Note, however, that
/// an Added entity may not yet have had its permanent key value created.
/// </para>
/// </summary>
/// <typeparam name="TSource">The type of the value.</typeparam>
/// <param name="observable">The parent observable.</param>
/// <returns>An instance of <see cref="IProviderObservable{TSource}"/>.</returns>
public static IProviderObservable <TSource> ReloadEntity <TSource>(
this IProviderObservable <TSource> observable)
where TSource : class =>
observable.WithEntityEntryAsync(async s => await s.ReloadAsync());
