/// <summary>
/// Returns an instance of a resource repository accessor for a Has Many relationship.
/// </summary>
/// <typeparam name="TEntity">The type of entity to return.</typeparam>
/// <param name="relationship">The relationship that defines the accessor to return.</param>
/// <returns>The resource repository accessor instance.</returns>
Func <IDatabase, IRepositoryAccessor <TEntity> > CreateHasManyAccessor <TEntity>(IHasManyRelationship relationship)
{
var propertyName = GuessDatabasePropertyName(typeof(TEntity));
return(CreateRepositoryAccessorFactory <TEntity>(propertyName, $"GetBy{GuessForeignKeyPropertyName(relationship)}Async"));
}
/// <summary>
/// Returns the name of the foreign key for the relationship.
/// </summary>
/// <param name="relationship">The relationship to guess the name of the foreign key from.</param>
/// <returns>The name of the foreign key property.</returns>
string GuessForeignKeyPropertyName(IHasManyRelationship relationship)
{
var inverse = relationship.Inverse(ContractResolver) as IBelongsToRelationship;
return(inverse?.BackingField?.Name);
}
/// <summary>
/// Returns an instance of a resource repository accessor for a Has Many relationship.
/// </summary>
/// <typeparam name="TEntity">The type of entity to return.</typeparam>
/// <param name="relationship">The relationship that defines the accessor to return.</param>
/// <returns>The resource repository accessor instance.</returns>
public Func <IDatabase, IRepositoryAccessor <TEntity> > GetOrCreateHasManyAccessor <TEntity>(IHasManyRelationship relationship)
{
return((Func <IDatabase, IRepositoryAccessor <TEntity> >)_cache.GetOrAdd(relationship, r => CreateHasManyAccessor <TEntity>((IHasManyRelationship)r)));
}
/// <summary>
/// Get or create an instance of a has many resource accessor.
/// </summary>
/// <typeparam name="TSource">The type of the source resource to enrich.</typeparam>
/// <typeparam name="TDestination">The type of the destination resource that is enriched on the source.</typeparam>
/// <param name="relationship">The relationship to create the accessor for.</param>
/// <returns>The has many resource accessor.</returns>
public IHasManyResourceAccessor <TSource, TDestination> GetOrCreateHasManyAccessor <TSource, TDestination>(IHasManyRelationship relationship)
{
return((IHasManyResourceAccessor <TSource, TDestination>)_cache.GetOrAdd(relationship, r => CreateHasManyAccessor <TSource, TDestination>((IHasManyRelationship)r)));
}
/// <summary>
/// Get or create an instance of a has many resource accessor.
/// </summary>
/// <typeparam name="TSource">The type of the source resource to enrich.</typeparam>
/// <typeparam name="TDestination">The type of the destination resource that is enriched on the source.</typeparam>
/// <param name="relationship">The relationship to create the accessor for.</param>
/// <returns>The has many resource accessor.</returns>
IHasManyResourceAccessor <TSource, TDestination> CreateHasManyAccessor <TSource, TDestination>(IHasManyRelationship relationship)
{
var sourceParameter = Expression.Parameter(typeof(TSource));
var destinationParameter = Expression.Parameter(typeof(TDestination));
var destinationEnumerableParameter = Expression.Parameter(typeof(IEnumerable <TDestination>));
var constructor = typeof(List <TDestination>).GetConstructor(new[] { typeof(IEnumerable <TDestination>) });
return(new DelegatingHasManyResourceAccessor <TSource, TDestination>(
Expression
.Lambda <Func <TDestination, int> >(
Expression.PropertyOrField(
destinationParameter,
GuessForeignKeyPropertyName(relationship)),
destinationParameter)
.Compile(),
Expression
.Lambda <Action <TSource, IEnumerable <TDestination> > >(
Expression.Assign(
Expression.PropertyOrField(
sourceParameter,
relationship.Name),
Expression.Convert(
Expression.New(constructor, destinationEnumerableParameter),
typeof(IReadOnlyList <TDestination>))),
sourceParameter,
destinationEnumerableParameter)
.Compile()));
}
/// <summary>
/// Create a belongs to enricher for the given relationship.
/// </summary>
/// <param name="relationship">The relationship to create the enricher from.</param>
/// <param name="database">The database to perform the enrichment within.</param>
/// <returns>The enricher for the given resource and relationship.</returns>
IResourceEnricher <TSource, TDestination> CreateHasManyEnricher <TSource, TDestinationEntity, TDestination>(IHasManyRelationship relationship, IDatabase database)
where TSource : IEntityWithId
where TDestinationEntity : IEntityWithId
where TDestination : IEntityWithId
{
var foreignKeyAccessor = _resourceAccessorFactory.GetOrCreateHasManyAccessor <TSource, TDestination>(relationship);
var repositoryAccessorFactory = _repositoryAccessorFactory.GetOrCreateHasManyAccessor <TDestinationEntity>(relationship);
return(new DelegatingHasManyResourceEnricher <TSource, TDestinationEntity, TDestination>(
foreignKeyAccessor,
repositoryAccessorFactory(database)));
}
/// <summary>
/// Create a has many enricher for the given relationship.
/// </summary>
/// <typeparam name="TSource">The resource type to create the enricher for.</typeparam>
/// <typeparam name="TDestination">The resource type on the other end of the relationship that is being enriched from.</typeparam>
/// <param name="relationship">The relationship to create the enricher from.</param>
/// <param name="database">The database to perform the enrichment within.</param>
/// <returns>The enricher for the given resource and relationship.</returns>
IResourceEnricher <TSource, TDestination> CreateHasManyEnricher <TSource, TDestination>(IHasManyRelationship relationship, IDatabase database)
{
var parameters = new[]
{
Expression.Parameter(typeof(IHasManyRelationship)),
Expression.Parameter(typeof(IDatabase))
};
var methodCallExpression = Expression.Call(
Expression.Constant(this),
nameof(CreateHasManyEnricher),
new[]
{
typeof(TSource),
relationship.RelatedTo.BaseType,
relationship.RelatedTo
},
// ReSharper disable once CoVariantArrayConversion
parameters);
var @delegate = Expression
.Lambda <Func <IHasManyRelationship, IDatabase, IResourceEnricher <TSource, TDestination> > >(
methodCallExpression,
parameters)
.Compile();
return(@delegate(relationship, database));
}