private Expression TryBindProperty(Expression originalExpression, Expression newExpression, string navigationMemberName)
{
if (newExpression is NavigationBindingExpression navigationBindingExpression)
{
if (navigationBindingExpression.RootParameter == _rootParameter)
{
var navigation = navigationBindingExpression.EntityType.FindNavigation(navigationMemberName);
if (navigation != null)
{
var navigationTreeNode = NavigationTreeNode.Create(
navigationBindingExpression.SourceMapping, navigation, navigationBindingExpression.NavigationTreeNode, _bindInclude);
return(new NavigationBindingExpression(
navigationBindingExpression.RootParameter,
navigationTreeNode,
navigation.GetTargetType(),
navigationBindingExpression.SourceMapping,
originalExpression.Type));
}
}
}
else
{
foreach (var sourceMapping in _sourceMappings)
{
var candidates = sourceMapping.NavigationTree.Flatten()
.SelectMany(n => n.FromMappings, (n, m) => (navigationTreeNode: n, path: m)).ToList();
var match = TryFindMatchingNavigationTreeNode(originalExpression, candidates);
if (match.navigationTreeNode != null)
{
return(new NavigationBindingExpression(
match.rootParameter,
match.navigationTreeNode,
match.navigationTreeNode.Navigation?.GetTargetType() ?? sourceMapping.RootEntityType,
sourceMapping,
originalExpression.Type));
}
}
}
return(null);
}
/// <summary>
/// Creates a navigation node from the given <paramref name="element"/>.
/// </summary>
/// <param name="element">The current XML element.</param>
/// <param name="canHaveChildren">Whether the element can have children.</param>
/// <returns>
/// The new <see cref="NavigationTreeNode"/>.
/// </returns>
/// <exception cref="XmlNavigationException">When the node is invalid.</exception>
protected virtual NavigationTreeNode CreateNode(XElement element, bool canHaveChildren)
{
var node = CreateNodeFromXml(element);
foreach (var attr in element.Attributes())
{
var attrName = attr.Name.LocalName ?? string.Empty;
if (attrName.Length <= RouteParamAttributePrefix.Length ||
!attrName.StartsWith(RouteParamAttributePrefix) ||
string.Equals(RouteNameAttributeName, attrName, StringComparison.OrdinalIgnoreCase) ||
string.Equals(RouteNameAttributeAltName, attrName, StringComparison.OrdinalIgnoreCase))
{
// We are going to ignore the "route-name" attribute
continue;
}
var name = attrName.Substring(RouteParamAttributePrefix.Length);
if (!string.IsNullOrEmpty(name))
{
// We got a valid parameter name, we can continue
node.RouteParameters.TryAdd(name, attr.Value);
}
}
// Retrieves a value indicating which kind of user the node should be hidden from
var hideFrom = GetAttributeValue(element, HideFromAttributeName) ??
GetAttributeValue(element, HideFromAttributeAltName);
if (!string.IsNullOrWhiteSpace(hideFrom))
{
// Determine if the hide-from value is valid
if (!Enum.TryParse <HideNodeFrom>(hideFrom, true, out var result))
{
// Unknown value
throw new XmlNavigationException(
$"The value '{hideFrom}' is not allowed for the '{HideFromAttributeName}' attribute."
);
}
node.HideNodeFrom = result;
}
// Determine if the node can have children
var navigationNode = new NavigationTreeNode(node);
if (!canHaveChildren)
{
// The node isn't allowed to have children, how sad
return(navigationNode);
}
// Retrieve all the children for the node
var childElements = element.Elements(NodeElementName);
foreach (var child in childElements)
{
var childNode = CreateNode(child, true);
navigationNode.AddChild(childNode);
}
// Done
return(navigationNode);
}
private IncludeExpression CreateIncludeCall(Expression caller, NavigationTreeNode node, ParameterExpression rootParameter, SourceMapping sourceMapping)
=> node.Navigation.IsCollection()
? CreateIncludeCollectionCall(caller, node, rootParameter, sourceMapping)
: CreateIncludeReferenceCall(caller, node, rootParameter, sourceMapping);
private IncludeExpression CreateIncludeCollectionCall(Expression caller, NavigationTreeNode node, ParameterExpression rootParameter, SourceMapping sourceMapping)
{
var included = CollectionNavigationRewritingVisitor.CreateCollectionNavigationExpression(node, rootParameter, sourceMapping);
return(new IncludeExpression(caller, included, node.Navigation));
}
private void Remove(NavigationTreeNode childNode)
{
childNodes.Remove(childNode);
childNode.Parent = null;
}
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);
}
