/// <summary>
/// Pre flattens properties referenced in aggregate clause to avoid generation of nested queries by EF.
/// For query like groupby((A), aggregate(B/C with max as Alias1, B/D with max as Alias2)) we need to generate
/// .Select(
/// $it => new FlattenninWrapper () {
/// Source = $it, // Will used in groupby stage
/// Container = new {
/// Value = $it.B.C
/// Next = new {
/// Value = $it.B.D
/// }
/// }
/// }
/// )
/// Also we need to populate expressions to access B/C and B/D in aggregate stage. It will look like:
/// B/C : $it.Container.Value
/// B/D : $it.Container.Next.Value
/// </summary>
/// <param name="query"></param>
/// <returns>Query with Select that flattens properties</returns>
private IQueryable FlattenReferencedProperties(IQueryable query)
{
if (_aggregateExpressions != null &&
_aggregateExpressions.OfType <AggregateExpression>().Any(e => e.Method != AggregationMethod.VirtualPropertyCount) &&
_groupingProperties != null &&
_groupingProperties.Any() &&
(FlattenedPropertyContainer == null || !FlattenedPropertyContainer.Any()))
{
var wrapperType = typeof(FlatteningWrapper <>).MakeGenericType(this.ElementType);
var sourceProperty = wrapperType.GetProperty("Source");
List <MemberAssignment> wta = new List <MemberAssignment>();
wta.Add(Expression.Bind(sourceProperty, this.LambdaParameter));
var aggrregatedPropertiesToFlatten = _aggregateExpressions.OfType <AggregateExpression>().Where(e => e.Method != AggregationMethod.VirtualPropertyCount).ToList();
// Generated Select will be stack like, meaning that first property in the list will be deepest one
// For example if we add $it.B.C, $it.B.D, select will look like
// new {
// Value = $it.B.C
// Next = new {
// Value = $it.B.D
// }
// }
// We are generated references (in currentContainerExpression) from the begining of the Select ($it.Value, then $it.Next.Value etc.)
// We have proper match we need insert properties in reverse order
// After this
// properties = { $it.B.D, $it.B.C}
// _preFlattendMAp = { {$it.B.C, $it.Value}, {$it.B.D, $it.Next.Value} }
var properties = new NamedPropertyExpression[aggrregatedPropertiesToFlatten.Count];
var aliasIdx = aggrregatedPropertiesToFlatten.Count - 1;
var aggParam = Expression.Parameter(wrapperType, "$it");
var currentContainerExpression = Expression.Property(aggParam, GroupByContainerProperty);
foreach (var aggExpression in aggrregatedPropertiesToFlatten)
{
var alias = "Property" + aliasIdx.ToString(CultureInfo.CurrentCulture); // We just need unique alias, we aren't going to use it
// Add Value = $it.B.C
var propAccessExpression = BindAccessor(aggExpression.Expression);
var type = propAccessExpression.Type;
propAccessExpression = WrapConvert(propAccessExpression);
properties[aliasIdx] = new NamedPropertyExpression(Expression.Constant(alias), propAccessExpression);
// Save $it.Container.Next.Value for future use
UnaryExpression flatAccessExpression = Expression.Convert(
Expression.Property(currentContainerExpression, "Value"),
type);
currentContainerExpression = Expression.Property(currentContainerExpression, "Next");
_preFlattenedMap.Add(aggExpression.Expression, flatAccessExpression);
aliasIdx--;
}
var wrapperProperty = ResultClrType.GetProperty(GroupByContainerProperty);
wta.Add(Expression.Bind(wrapperProperty, AggregationPropertyContainer.CreateNextNamedPropertyContainer(properties)));
var flatLambda = Expression.Lambda(Expression.MemberInit(Expression.New(wrapperType), wta), LambdaParameter);
query = ExpressionHelpers.Select(query, flatLambda, this.ElementType);
// We applied flattening let .GroupBy know about it.
this.LambdaParameter = aggParam;
}
return(query);
}
private Expression BuildPropertyContainer(IEdmEntityType elementType, Expression source,
Dictionary <IEdmNavigationProperty, ExpandedNavigationSelectItem> propertiesToExpand,
ISet <IEdmStructuralProperty> propertiesToInclude, ISet <IEdmStructuralProperty> autoSelectedProperties, bool isSelectingOpenTypeSegments)
{
IList <NamedPropertyExpression> includedProperties = new List <NamedPropertyExpression>();
foreach (KeyValuePair <IEdmNavigationProperty, ExpandedNavigationSelectItem> kvp in propertiesToExpand)
{
IEdmNavigationProperty propertyToExpand = kvp.Key;
ExpandedNavigationSelectItem expandItem = kvp.Value;
SelectExpandClause projection = expandItem.SelectAndExpand;
Expression propertyName = CreatePropertyNameExpression(elementType, propertyToExpand, source);
Expression propertyValue = CreatePropertyValueExpressionWithFilter(elementType, propertyToExpand, source,
expandItem.FilterOption);
Expression nullCheck = GetNullCheckExpression(propertyToExpand, propertyValue, projection);
Expression countExpression = CreateTotalCountExpression(propertyValue, expandItem);
// projection can be null if the expanded navigation property is not further projected or expanded.
if (projection != null)
{
propertyValue = ProjectAsWrapper(propertyValue, projection, propertyToExpand.ToEntityType(), expandItem.NavigationSource as IEdmEntitySet,
expandItem);
}
NamedPropertyExpression propertyExpression = new NamedPropertyExpression(propertyName, propertyValue);
if (projection != null)
{
if (!propertyToExpand.Type.IsCollection())
{
propertyExpression.NullCheck = nullCheck;
}
else if (_settings.PageSize != null)
{
propertyExpression.PageSize = _settings.PageSize.Value;
}
propertyExpression.TotalCount = countExpression;
propertyExpression.CountOption = expandItem.CountOption;
}
includedProperties.Add(propertyExpression);
}
foreach (IEdmStructuralProperty propertyToInclude in propertiesToInclude)
{
Expression propertyName = CreatePropertyNameExpression(elementType, propertyToInclude, source);
Expression propertyValue = CreatePropertyValueExpression(elementType, propertyToInclude, source);
includedProperties.Add(new NamedPropertyExpression(propertyName, propertyValue));
}
foreach (IEdmStructuralProperty propertyToInclude in autoSelectedProperties)
{
Expression propertyName = CreatePropertyNameExpression(elementType, propertyToInclude, source);
Expression propertyValue = CreatePropertyValueExpression(elementType, propertyToInclude, source);
includedProperties.Add(new NamedPropertyExpression(propertyName, propertyValue)
{
AutoSelected = true
});
}
if (isSelectingOpenTypeSegments)
{
var dynamicPropertyDictionary = EdmLibHelpers.GetDynamicPropertyDictionary(elementType, _model);
Expression propertyName = Expression.Constant(dynamicPropertyDictionary.Name);
Expression propertyValue = Expression.Property(source, dynamicPropertyDictionary.Name);
Expression nullablePropertyValue = ExpressionHelpers.ToNullable(propertyValue);
if (_settings.HandleNullPropagation == HandleNullPropagationOption.True)
{
// source == null ? null : propertyValue
propertyValue = Expression.Condition(
test: Expression.Equal(source, Expression.Constant(value: null)),
ifTrue: Expression.Constant(value: null, type: propertyValue.Type.ToNullable()),
ifFalse: nullablePropertyValue);
}
else
{
propertyValue = nullablePropertyValue;
}
includedProperties.Add(new NamedPropertyExpression(propertyName, propertyValue));
}
// create a property container that holds all these property names and values.
return(PropertyContainer.CreatePropertyContainer(includedProperties));
}
// new CollectionWrapper<ElementType> { Instance = source.Select((ElementType element) => new Wrapper { }) }
private Expression ProjectCollection(Expression source, Type elementType, SelectExpandClause selectExpandClause, IEdmEntityType entityType, IEdmEntitySet entitySet, ExpandedNavigationSelectItem expandedItem)
{
ParameterExpression element = Expression.Parameter(elementType);
// expression
// new Wrapper { }
Expression projection = ProjectElement(element, selectExpandClause, entityType, entitySet);
// expression
// (ElementType element) => new Wrapper { }
LambdaExpression selector = Expression.Lambda(projection, element);
if (expandedItem != null)
{
source = AddOrderByQueryForSource(source, expandedItem.OrderByOption, elementType);
}
if (_settings.PageSize.HasValue || (expandedItem != null && (expandedItem.TopOption.HasValue || expandedItem.SkipOption.HasValue)))
{
// nested paging. Need to apply order by first, and take one more than page size as we need to know
// whether the collection was truncated or not while generating next page links.
IEnumerable <IEdmStructuralProperty> properties =
entityType.Key().Any()
? entityType.Key()
: entityType
.StructuralProperties()
.Where(property => property.Type.IsPrimitive() && !property.Type.IsStream())
.OrderBy(property => property.Name);
if (expandedItem == null || expandedItem.OrderByOption == null)
{
bool alreadyOrdered = false;
foreach (var prop in properties)
{
source = ExpressionHelpers.OrderByPropertyExpression(source, prop.Name, elementType,
alreadyOrdered);
if (!alreadyOrdered)
{
alreadyOrdered = true;
}
}
}
if (expandedItem != null && expandedItem.SkipOption.HasValue)
{
Contract.Assert(expandedItem.SkipOption.Value <= Int32.MaxValue);
source = ExpressionHelpers.Skip(source, (int)expandedItem.SkipOption.Value, elementType,
_settings.EnableConstantParameterization);
}
if (expandedItem != null && expandedItem.TopOption.HasValue)
{
Contract.Assert(expandedItem.TopOption.Value <= Int32.MaxValue);
source = ExpressionHelpers.Take(source, (int)expandedItem.TopOption.Value, elementType,
_settings.EnableConstantParameterization);
}
source = ExpressionHelpers.Take(source, _settings.PageSize.Value + 1, elementType, _settings.EnableConstantParameterization);
}
// expression
// source.Select((ElementType element) => new Wrapper { })
Expression selectedExpresion = Expression.Call(GetSelectMethod(elementType, projection.Type), source, selector);
if (_settings.HandleNullPropagation == HandleNullPropagationOption.True)
{
// source == null ? null : projectedCollection
return(Expression.Condition(
test: Expression.Equal(source, Expression.Constant(null)),
ifTrue: Expression.Constant(null, selectedExpresion.Type),
ifFalse: selectedExpresion));
}
else
{
return(selectedExpresion);
}
}
internal Expression CreatePropertyValueExpressionWithFilter(IEdmEntityType elementType, IEdmProperty property,
Expression source, FilterClause filterClause)
{
Contract.Assert(elementType != null);
Contract.Assert(property != null);
Contract.Assert(source != null);
IEdmEntityType declaringType = property.DeclaringType as IEdmEntityType;
Contract.Assert(declaringType != null, "only entity types are projected.");
// derived property using cast
if (elementType != declaringType)
{
Type castType = EdmLibHelpers.GetClrType(declaringType, _model);
if (castType == null)
{
throw new ODataException("TODO: " /*Error.Format(SRResources.MappingDoesNotContainResourceType,
* declaringType.FullName())*/);
}
source = Expression.TypeAs(source, castType);
}
string propertyName = EdmLibHelpers.GetClrPropertyName(property, _model);
Expression propertyValue = Expression.Property(source, propertyName);
Type nullablePropertyType = propertyValue.Type.ToNullable();
Expression nullablePropertyValue = ExpressionHelpers.ToNullable(propertyValue);
if (filterClause != null && property.Type.IsCollection())
{
IEdmTypeReference edmElementType = property.Type.AsCollection().ElementType();
Type clrElementType = EdmLibHelpers.GetClrType(edmElementType, _model);
if (clrElementType == null)
{
throw new ODataException("TODO:" /*Error.Format(SRResources.MappingDoesNotContainResourceType,
* edmElementType.FullName())*/);
}
Expression filterSource =
typeof(IEnumerable).IsAssignableFrom(source.Type.GetProperty(propertyName).PropertyType)
? Expression.Call(
ExpressionHelperMethods.QueryableAsQueryable.MakeGenericMethod(clrElementType),
nullablePropertyValue)
: nullablePropertyValue;
Expression filterPredicate = FilterBinder.Bind(filterClause, clrElementType, /*_context.RequestContainer*/ null);
MethodCallExpression filterResult = Expression.Call(
ExpressionHelperMethods.QueryableWhereGeneric.MakeGenericMethod(clrElementType),
filterSource,
filterPredicate);
nullablePropertyType = filterResult.Type;
if (_settings.HandleNullPropagation == HandleNullPropagationOption.True)
{
// nullablePropertyValue == null ? null : filterResult
nullablePropertyValue = Expression.Condition(
test: Expression.Equal(nullablePropertyValue, Expression.Constant(value: null)),
ifTrue: Expression.Constant(value: null, type: nullablePropertyType),
ifFalse: filterResult);
}
else
{
nullablePropertyValue = filterResult;
}
}
if (_settings.HandleNullPropagation == HandleNullPropagationOption.True)
{
// source == null ? null : propertyValue
propertyValue = Expression.Condition(
test: Expression.Equal(source, Expression.Constant(value: null)),
ifTrue: Expression.Constant(value: null, type: nullablePropertyType),
ifFalse: nullablePropertyValue);
}
else
{
// need to cast this to nullable as EF would fail while materializing if the property is not nullable and source is null.
propertyValue = nullablePropertyValue;
}
return(propertyValue);
}
