protected override Expression VisitExtension(Expression extensionExpression)
{
if (extensionExpression is NavigationBindingExpression navigationBindingExpression)
{
if (navigationBindingExpression.RootParameter == _sourceParameter &&
navigationBindingExpression.NavigationTreeNode.Parent != null &&
navigationBindingExpression.NavigationTreeNode.IsCollection)
{
var lastNavigation = navigationBindingExpression.NavigationTreeNode.Navigation;
return(lastNavigation.ForeignKey.IsOwnership
? NavigationExpansionHelpers.CreateNavigationExpansionRoot(navigationBindingExpression, lastNavigation.GetTargetType(), lastNavigation)
: CreateCollectionNavigationExpression(navigationBindingExpression.NavigationTreeNode, navigationBindingExpression.RootParameter, navigationBindingExpression.SourceMapping));
}
else
{
return(extensionExpression);
}
}
return(base.VisitExtension(extensionExpression));
}
private Expression ProcessMemberPushdown(
Expression source,
NavigationExpansionExpression navigationExpansionExpression,
bool efProperty,
MemberInfo memberInfo,
string propertyName,
Type resultType)
{
// in case of nested FirstOrDefaults, we need to dig into the inner most - that's where the member finally gets pushed down to
if (navigationExpansionExpression.State.PendingSelector.Body is NavigationExpansionExpression navigationExpansionPendingSelector &&
navigationExpansionPendingSelector.State.PendingCardinalityReducingOperator != null)
{
var newPendingSelector = (NavigationExpansionExpression)ProcessMemberPushdown(source, navigationExpansionPendingSelector, efProperty, memberInfo, propertyName, resultType);
var newStateNested = new NavigationExpansionExpressionState(
navigationExpansionExpression.State.CurrentParameter,
navigationExpansionExpression.State.SourceMappings,
Expression.Lambda(newPendingSelector, navigationExpansionExpression.State.CurrentParameter),
applyPendingSelector: true,
navigationExpansionExpression.State.PendingOrderings,
navigationExpansionExpression.State.PendingIncludeChain,
// we need to remap cardinality reducing operator since it's source type has now changed
navigationExpansionExpression.State.PendingCardinalityReducingOperator.GetGenericMethodDefinition().MakeGenericMethod(newPendingSelector.Type),
navigationExpansionExpression.State.CustomRootMappings,
navigationExpansionExpression.State.MaterializeCollectionNavigation);
return(new NavigationExpansionExpression(
navigationExpansionExpression.Operand,
newStateNested,
resultType));
}
var selectorParameter = Expression.Parameter(source.Type, navigationExpansionExpression.State.CurrentParameter.Name);
var selectorBody = efProperty
? (Expression)Expression.Call(EF.PropertyMethod.MakeGenericMethod(resultType),
selectorParameter,
Expression.Constant(propertyName))
: Expression.MakeMemberAccess(selectorParameter, memberInfo);
if (navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.QueryableFirstOrDefaultMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.QueryableFirstOrDefaultPredicateMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.QueryableSingleOrDefaultMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.QueryableSingleOrDefaultPredicateMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.EnumerableFirstOrDefaultMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.EnumerableFirstOrDefaultPredicateMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.EnumerableSingleOrDefaultMethodInfo) ||
navigationExpansionExpression.State.PendingCardinalityReducingOperator.MethodIsClosedFormOf(LinqMethodHelpers.EnumerableSingleOrDefaultPredicateMethodInfo))
{
if (!selectorBody.Type.IsNullableType())
{
selectorBody = Expression.Convert(selectorBody, selectorBody.Type.MakeNullable());
}
}
var selector = Expression.Lambda(selectorBody, selectorParameter);
var remappedSelectorBody = ReplacingExpressionVisitor.Replace(
selectorParameter, navigationExpansionExpression.State.PendingSelector.Body, selector.Body);
var binder = new NavigationPropertyBindingVisitor(
navigationExpansionExpression.State.CurrentParameter,
navigationExpansionExpression.State.SourceMappings);
var boundSelectorBody = binder.Visit(remappedSelectorBody);
if (boundSelectorBody is NavigationBindingExpression navigationBindingExpression &&
navigationBindingExpression.NavigationTreeNode.Navigation != null)
{
if (navigationBindingExpression.NavigationTreeNode.IsCollection)
{
var lastNavigation = navigationBindingExpression.NavigationTreeNode.Navigation;
var collectionNavigationElementType = lastNavigation.ForeignKey.DeclaringEntityType.ClrType;
var entityQueryable = NullAsyncQueryProvider.Instance.CreateEntityQueryableExpression(collectionNavigationElementType);
var outerParameter = Expression.Parameter(collectionNavigationElementType, collectionNavigationElementType.GenerateParameterName());
var outerKeyAccess = NavigationExpansionHelpers.CreateKeyAccessExpression(
outerParameter,
lastNavigation.ForeignKey.Properties);
var innerParameter = Expression.Parameter(navigationExpansionExpression.Type);
var innerKeyAccessLambda = Expression.Lambda(
NavigationExpansionHelpers.CreateKeyAccessExpression(
innerParameter,
lastNavigation.ForeignKey.PrincipalKey.Properties),
innerParameter);
var combinedKeySelectorBody = ReplacingExpressionVisitor.Replace(
innerKeyAccessLambda.Parameters[0], navigationExpansionExpression.State.PendingSelector.Body, innerKeyAccessLambda.Body);
if (outerKeyAccess.Type != combinedKeySelectorBody.Type)
{
if (combinedKeySelectorBody.Type.IsNullableType())
{
outerKeyAccess = Expression.Convert(outerKeyAccess, combinedKeySelectorBody.Type);
}
else
{
combinedKeySelectorBody = Expression.Convert(combinedKeySelectorBody, outerKeyAccess.Type);
}
}
var rewrittenState = new NavigationExpansionExpressionState(
navigationExpansionExpression.State.CurrentParameter,
navigationExpansionExpression.State.SourceMappings,
Expression.Lambda(combinedKeySelectorBody, navigationExpansionExpression.State.CurrentParameter),
applyPendingSelector: true,
navigationExpansionExpression.State.PendingOrderings,
navigationExpansionExpression.State.PendingIncludeChain,
// we need to remap cardinality reducing operator since it's source type has now changed
navigationExpansionExpression.State.PendingCardinalityReducingOperator.GetGenericMethodDefinition().MakeGenericMethod(combinedKeySelectorBody.Type),
navigationExpansionExpression.State.CustomRootMappings,
materializeCollectionNavigation: null);
var rewrittenNavigationExpansionExpression = new NavigationExpansionExpression(navigationExpansionExpression.Operand, rewrittenState, combinedKeySelectorBody.Type);
var inner = new NavigationExpansionReducingVisitor().Visit(rewrittenNavigationExpansionExpression);
var predicate = Expression.Lambda(
Expression.Equal(outerKeyAccess, inner),
outerParameter);
var whereMethodInfo = LinqMethodHelpers.QueryableWhereMethodInfo.MakeGenericMethod(collectionNavigationElementType);
var rewritten = Expression.Call(
whereMethodInfo,
entityQueryable,
predicate);
var entityType = lastNavigation.ForeignKey.DeclaringEntityType;
return(NavigationExpansionHelpers.CreateNavigationExpansionRoot(rewritten, entityType, materializeCollectionNavigation: null));
}
else
{
return(ProcessSelectCore(
navigationExpansionExpression.Operand,
navigationExpansionExpression.State,
selector,
selectorBody.Type));
}
}
var newState = new NavigationExpansionExpressionState(
navigationExpansionExpression.State.CurrentParameter,
navigationExpansionExpression.State.SourceMappings,
Expression.Lambda(boundSelectorBody, navigationExpansionExpression.State.CurrentParameter),
applyPendingSelector: true,
navigationExpansionExpression.State.PendingOrderings,
navigationExpansionExpression.State.PendingIncludeChain,
// we need to remap cardinality reducing operator since it's source type has now changed
navigationExpansionExpression.State.PendingCardinalityReducingOperator.GetGenericMethodDefinition().MakeGenericMethod(boundSelectorBody.Type),
navigationExpansionExpression.State.CustomRootMappings,
navigationExpansionExpression.State.MaterializeCollectionNavigation);
// TODO: expand navigations
var result = new NavigationExpansionExpression(
navigationExpansionExpression.Operand,
newState,
selectorBody.Type);
return(resultType != result.Type
? (Expression)Expression.Convert(result, resultType)
: result);
}
public static Expression CreateCollectionNavigationExpression(
NavigationTreeNode navigationTreeNode, ParameterExpression rootParameter, SourceMapping sourceMapping)
{
var collectionEntityType = navigationTreeNode.Navigation.ForeignKey.DeclaringEntityType;
Expression operand;
if (navigationTreeNode.IncludeState == NavigationState.Pending ||
navigationTreeNode.ExpansionState == NavigationState.Pending)
{
var entityQueryable = (Expression)NullAsyncQueryProvider.Instance.CreateEntityQueryableExpression(collectionEntityType.ClrType);
var outerBinding = new NavigationBindingExpression(
rootParameter,
navigationTreeNode.Parent,
navigationTreeNode.Navigation.DeclaringEntityType,
sourceMapping,
navigationTreeNode.Navigation.DeclaringEntityType.ClrType);
var outerKeyAccess = NavigationExpansionHelpers.CreateKeyAccessExpression(
outerBinding,
navigationTreeNode.Navigation.ForeignKey.PrincipalKey.Properties,
addNullCheck: outerBinding.NavigationTreeNode.Optional);
var collectionCurrentParameter = Expression.Parameter(
collectionEntityType.ClrType, collectionEntityType.ClrType.GenerateParameterName());
var innerKeyAccess = NavigationExpansionHelpers.CreateKeyAccessExpression(
collectionCurrentParameter,
navigationTreeNode.Navigation.ForeignKey.Properties);
var predicate = Expression.Lambda(
CreateKeyComparisonExpressionForCollectionNavigationSubquery(
outerKeyAccess,
innerKeyAccess,
outerBinding),
collectionCurrentParameter);
operand = Expression.Call(
LinqMethodHelpers.QueryableWhereMethodInfo.MakeGenericMethod(collectionEntityType.ClrType),
entityQueryable,
predicate);
}
else
{
operand = new NavigationBindingExpression(
rootParameter,
navigationTreeNode,
collectionEntityType,
sourceMapping,
collectionEntityType.ClrType);
}
var result = NavigationExpansionHelpers.CreateNavigationExpansionRoot(
operand, collectionEntityType, navigationTreeNode.Navigation);
// this is needed for cases like: root.Include(r => r.Collection).ThenInclude(c => c.Reference).Select(r => r.Collection)
// result should be elements of the collection navigation with their 'Reference' included
var newSourceMapping = result.State.SourceMappings.Single();
IncludeHelpers.CopyIncludeInformation(navigationTreeNode, newSourceMapping.NavigationTree, newSourceMapping);
return(result);
}