private (NavigationExpansionExpression navigationExpression, Expression nullKeyExpression) CreateNullComparisonArguments(
NavigationBindingExpression navigationBindingExpression,
NavigationExpansionExpression navigationExpansionExpression)
{
var navigationKeyAccessExpression = NavigationExpansionHelpers.CreateKeyAccessExpression(
navigationBindingExpression,
new[] { navigationBindingExpression.EntityType.FindPrimaryKey().Properties.First() },
addNullCheck: true);
var nullKeyExpression = NavigationExpansionHelpers.CreateNullKeyExpression(
navigationKeyAccessExpression.Type,
keyCount: 1);
var newNavigationExpansionExpressionState = new NavigationExpansionExpressionState(
navigationExpansionExpression.State.CurrentParameter,
navigationExpansionExpression.State.SourceMappings,
Expression.Lambda(navigationKeyAccessExpression, navigationExpansionExpression.State.PendingSelector.Parameters[0]),
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(navigationKeyAccessExpression.Type),
navigationExpansionExpression.State.CustomRootMappings,
navigationExpansionExpression.State.MaterializeCollectionNavigation);
var navigationExpression = new NavigationExpansionExpression(
navigationExpansionExpression.Operand,
newNavigationExpansionExpressionState,
navigationKeyAccessExpression.Type);
return(navigationExpression, nullKeyExpression);
}
private Expression TryRewriteNavigationComparison(Expression left, Expression right, bool equality)
{
var leftBinding = left as NavigationBindingExpression;
var rightBinding = right as NavigationBindingExpression;
var leftNullConstant = left.IsNullConstantExpression();
var rightNullConstant = right.IsNullConstantExpression();
Expression newLeft = null;
Expression newRight = null;
// comparing two different collection navigations always returns false
if (leftBinding != null &&
rightBinding != null &&
leftBinding.NavigationTreeNode.Navigation != rightBinding.NavigationTreeNode.Navigation &&
(leftBinding.NavigationTreeNode.IsCollection || rightBinding.NavigationTreeNode.IsCollection))
{
if (leftBinding.NavigationTreeNode.IsCollection)
{
var parentTreeNode = leftBinding.NavigationTreeNode.Parent;
parentTreeNode.Children.Remove(leftBinding.NavigationTreeNode);
}
if (rightBinding.NavigationTreeNode.IsCollection)
{
var parentTreeNode = rightBinding.NavigationTreeNode.Parent;
parentTreeNode.Children.Remove(rightBinding.NavigationTreeNode);
}
return(Expression.Constant(false));
}
if (leftBinding != null && rightBinding != null &&
leftBinding.EntityType == rightBinding.EntityType)
{
if (leftBinding.NavigationTreeNode.Navigation == rightBinding.NavigationTreeNode.Navigation &&
leftBinding.NavigationTreeNode.IsCollection)
{
leftBinding = CreateParentBindingExpression(leftBinding);
rightBinding = CreateParentBindingExpression(rightBinding);
}
// TODO: what about entities without PKs?
var primaryKeyProperties = leftBinding.EntityType.FindPrimaryKey().Properties;
newLeft = NavigationExpansionHelpers.CreateKeyAccessExpression(leftBinding, primaryKeyProperties, addNullCheck: leftBinding.NavigationTreeNode.Optional);
newRight = NavigationExpansionHelpers.CreateKeyAccessExpression(rightBinding, primaryKeyProperties, addNullCheck: rightBinding.NavigationTreeNode.Optional);
}
if (leftBinding != null &&
rightNullConstant)
{
if (leftBinding.NavigationTreeNode.IsCollection)
{
leftBinding = CreateParentBindingExpression(leftBinding);
}
// TODO: what about entities without PKs?
var primaryKeyProperties = leftBinding.EntityType.FindPrimaryKey().Properties;
newLeft = NavigationExpansionHelpers.CreateKeyAccessExpression(leftBinding, primaryKeyProperties, addNullCheck: leftBinding.NavigationTreeNode.Optional);
newRight = NavigationExpansionHelpers.CreateNullKeyExpression(newLeft.Type, primaryKeyProperties.Count);
}
if (rightBinding != null &&
leftNullConstant)
{
if (rightBinding.NavigationTreeNode.IsCollection)
{
rightBinding = CreateParentBindingExpression(rightBinding);
}
// TODO: what about entities without PKs?
var primaryKeyProperties = rightBinding.EntityType.FindPrimaryKey().Properties;
newRight = NavigationExpansionHelpers.CreateKeyAccessExpression(rightBinding, primaryKeyProperties, addNullCheck: rightBinding.NavigationTreeNode.Optional);
newLeft = NavigationExpansionHelpers.CreateNullKeyExpression(newRight.Type, primaryKeyProperties.Count);
}
if (newLeft == null || newRight == null)
{
return(null);
}
if (newLeft.Type != newRight.Type)
{
if (newLeft.Type.IsNullableType())
{
newRight = Expression.Convert(newRight, newLeft.Type);
}
else
{
newLeft = Expression.Convert(newLeft, newRight.Type);
}
}
return(equality
? Expression.Equal(newLeft, newRight)
: Expression.NotEqual(newLeft, newRight));
}