private void LoadAssociationsForEach <T>(List <T> entities, LoadOptions loadOptions)
{
var typeTLoadOptions = loadOptions.LoadWithOptions
.Where(lo => lo.Member.Parameters.Single().Type == typeof(T))
.Select(lo => new { LoadOption = lo, Member = ((MemberExpression)lo.Member.Body).Member });
foreach (var loadOption in typeTLoadOptions)
{
var thisSideAssociationProperty = loadOption.Member as PropertyInfo;
if (thisSideAssociationProperty == null)
{
throw new NotSupportedException("Only properties are supported");
}
MetaType type = this.GetMetaType <T>();
MetaAssociation association = type.Associations.Where(assoc => assoc.ThisMember.Name == thisSideAssociationProperty.Name).SingleOrDefault();
if (association == null)
{
throw new InvalidOperationException(String.Format(CultureInfo.InvariantCulture, "Association mapping for property {0} of class {1} is not defined.", thisSideAssociationProperty.Name, typeof(T).FullName));
}
// find all possible associated entities
Type associatedType = thisSideAssociationProperty.PropertyType;
if (!association.IsForeignKey)
{
// there is a collection on this side, get collection item type
Type listInterface = associatedType.GetInterfaces().Where(i => (i.IsGenericType && i.GetGenericTypeDefinition() == typeof(IList <>))).SingleOrDefault();
if (listInterface == null)
{
throw new InvalidOperationException("Non-FK association property type must implement IList<T> interface");
}
associatedType = listInterface.GetGenericArguments().Single();
// fill with empty lists
foreach (T entity in entities)
{
object localEntity = entity;
association.ThisMember.StorageAccessor.SetBoxedValue(ref localEntity, Activator.CreateInstance(association.ThisMember.Type));
}
}
// first list to join
Expression allTsConst = Expression.Constant(entities.AsQueryable());
// second list to join
var allAssociatedEntitiesQuery = this.All(associatedType, loadOptions);
// appying Filter expressions if present
if (loadOption.LoadOption.Association != null)
{
var allAssociatedEntitiesFilteredEnumerableExpression = new ExpressionReplacer(loadOption.LoadOption.Member.Body, allAssociatedEntitiesQuery.Expression).Visit(loadOption.LoadOption.Association.Body);
var asQueryableGenericMethod = TypeSystem.FindQueryableMethod("AsQueryable", new[] { typeof(IEnumerable <>).MakeGenericType(associatedType) }, new[] { associatedType });
var allAssociatedEntitiesFilteredQueryableExpression = Expression.Call(asQueryableGenericMethod, allAssociatedEntitiesFilteredEnumerableExpression);
allAssociatedEntitiesQuery = allAssociatedEntitiesQuery.Provider.CreateQuery(allAssociatedEntitiesFilteredQueryableExpression);
}
Expression allAssociatedEntitiesExpression = allAssociatedEntitiesQuery.Expression;
// outerKeySelector
var paramA1 = Expression.Parameter(typeof(T), "a");
MemberExpression thisKeyPropertyExpression = paramA1.Property(association.ThisKey.First().Member as PropertyInfo);
// innerKeySelector
var paramB1 = Expression.Parameter(associatedType, "b");
MemberExpression otherKeyPropertyExpression = paramB1.Property(association.OtherKey.First().Member as PropertyInfo);
if (thisKeyPropertyExpression.Type.IsGenericType && thisKeyPropertyExpression.Type.GetGenericTypeDefinition() == typeof(Nullable <>))
{
var nullableFilterParamA1 = Expression.Parameter(typeof(T), "a");
MemberExpression nullableFilterPropertyExpression =
nullableFilterParamA1
.Property(association.ThisKey.First().Member as PropertyInfo)
.Property("HasValue");
LambdaExpression whereHasValueFilter = nullableFilterParamA1.ToLambda(nullableFilterPropertyExpression);
allTsConst = allTsConst.Where(whereHasValueFilter);
thisKeyPropertyExpression = thisKeyPropertyExpression.Property("Value");
}
if (otherKeyPropertyExpression.Type.IsGenericType && otherKeyPropertyExpression.Type.GetGenericTypeDefinition() == typeof(Nullable <>))
{
var nullableFilterParamB1 = Expression.Parameter(associatedType, "b");
MemberExpression nullableFilterPropertyExpression =
nullableFilterParamB1
.Property(association.OtherKey.First().Member as PropertyInfo)
.Property("HasValue");
LambdaExpression whereHasValueFilter = nullableFilterParamB1.ToLambda(nullableFilterPropertyExpression);
allAssociatedEntitiesExpression = allAssociatedEntitiesExpression.Where(whereHasValueFilter);
otherKeyPropertyExpression = otherKeyPropertyExpression.Property("Value");
}
var outerKeySelector = Expression.Quote(paramA1.ToLambda(thisKeyPropertyExpression));
var innerKeySelector = Expression.Quote(paramB1.ToLambda(otherKeyPropertyExpression));
var keyValueType = typeof(KeyValuePair <,>).MakeGenericType(typeof(T), associatedType);
// resultSelector
var paramA2 = Expression.Parameter(typeof(T), "a");
var paramB2 = Expression.Parameter(associatedType, "b");
var resultSelector = Expression.Quote(
Expression.Lambda(
Expression.New(
keyValueType.GetConstructors().Single(),
paramA2,
paramB2),
paramA2,
paramB2));
var joinMethod = typeof(Queryable).GetMethods().Where(m => m.Name == "Join" && m.GetParameters().Count() == 5).Single();
var joinMethodGeneric = joinMethod.MakeGenericMethod(typeof(T), associatedType, thisKeyPropertyExpression.Type, keyValueType);
// join!
var joinExpression = Expression.Call(null, joinMethodGeneric, allTsConst, allAssociatedEntitiesExpression, outerKeySelector, innerKeySelector, resultSelector);
var joinResult = allAssociatedEntitiesQuery.Provider.Execute(joinExpression) as IEnumerable;
var keyProperty = keyValueType.GetProperty("Key");
var valueProperty = keyValueType.GetProperty("Value");
foreach (var pair in joinResult)
{
var thisObject = keyProperty.GetValue(pair, new object[0]);
var otherObject = valueProperty.GetValue(pair, new object[0]);
if (association.IsForeignKey)
{
association.ThisMember.StorageAccessor.SetBoxedValue(
ref thisObject,
otherObject);
}
else
{
var list = association.ThisMember.StorageAccessor.GetBoxedValue(thisObject);
list.GetType().GetMethod("Add").Invoke(list, new[] { otherObject });
}
}
}
}