protected override Expression VisitExtension(Expression extensionExpression)
{
switch (extensionExpression)
{
case NavigationBindingExpression navigationBindingExpression
when navigationBindingExpression.RootParameter == _rootParameter:
{
var node = navigationBindingExpression.NavigationTreeNode;
var navigations = new List <INavigation>();
while (node != null)
{
if (node.Navigation != null)
{
navigations.Add(node.Navigation);
}
node = node.Parent;
}
var result = navigationBindingExpression.RootParameter.BuildPropertyAccess(
navigationBindingExpression.NavigationTreeNode.ToMapping,
navigations.Count == navigationBindingExpression.NavigationTreeNode.ToMapping.Count ? navigations : null);
return(result.Type != navigationBindingExpression.Type
? Expression.Convert(result, navigationBindingExpression.Type)
: result);
}
case CustomRootExpression customRootExpression
when customRootExpression.RootParameter == _rootParameter:
{
var result = _rootParameter.BuildPropertyAccess(customRootExpression.Mapping);
return(result.Type != customRootExpression.Type
? Expression.Convert(result, customRootExpression.Type)
: result);
}
case NavigationExpansionRootExpression _:
case NavigationExpansionExpression _:
{
var result = new NavigationExpansionReducingVisitor().Visit(extensionExpression);
return(Visit(result));
}
default:
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);
}
