protected override Expression VisitSubQuery(SubQueryExpression expression)
{
var oldParentSelector = _parentSelector;
_parentSelector = expression.QueryModel.SelectClause.Selector;
expression.QueryModel.TransformExpressions(Visit);
_parentSelector = oldParentSelector;
var querySourceReferenceExpression
= expression.QueryModel.SelectClause.Selector
as QuerySourceReferenceExpression;
if (querySourceReferenceExpression != null)
{
var querySourceTracingExpressionVisitor = new QuerySourceTracingExpressionVisitor();
var resultQuerySource
= querySourceTracingExpressionVisitor
.FindResultQuerySourceReferenceExpression(
_parentSelector,
querySourceReferenceExpression.ReferencedQuerySource);
if ((resultQuerySource == null) &&
!(expression.QueryModel.ResultOperators.LastOrDefault() is OfTypeResultOperator))
{
_querySources[querySourceReferenceExpression.ReferencedQuerySource]--;
}
}
return(expression);
}
private void ApplyIncludesForEagerLoadedNavigations(QuerySourceReferenceExpression querySourceReferenceExpression, QueryModel queryModel)
{
if (_querySourceTracingExpressionVisitor
.FindResultQuerySourceReferenceExpression(
queryModel.SelectClause.Selector,
querySourceReferenceExpression.ReferencedQuerySource) != null)
{
var entityType = _queryCompilationContext.Model.FindEntityType(querySourceReferenceExpression.Type);
if (entityType != null)
{
var stack = new Stack <INavigation>();
WalkNavigations(querySourceReferenceExpression, entityType, stack);
}
}
}
private void AdjustForResultOperators(QueryModel queryModel)
{
var isSubQuery = _queryModelStack.Count > 0;
var finalResultOperator = queryModel.ResultOperators.LastOrDefault();
if (isSubQuery && finalResultOperator is GroupResultOperator groupResultOperator)
{
if (!(groupResultOperator.KeySelector is MemberInitExpression))
{
// This is to compensate for the fact that we have to demote querysources found in selector for GroupBy
// TODO: See #11215
foreach (var querySource in TraverseQuerySources(queryModel.SelectClause.Selector))
{
DemoteQuerySource(querySource);
}
if (groupResultOperator.ElementSelector is QuerySourceReferenceExpression qsre)
{
DemoteQuerySource(qsre.ReferencedQuerySource);
}
return;
}
}
var referencedQuerySource
= queryModel.SelectClause.Selector.TryGetReferencedQuerySource()
?? queryModel.MainFromClause.FromExpression.TryGetReferencedQuerySource();
// The selector may not have been a QSRE but this query model may still have something that needs adjusted.
// Example:
// context.Orders.GroupBy(o => o.CustomerId).Select(g => new { g.Key, g.Sum(o => o.TotalAmount) })
// The g.Sum(...) will result in a subquery model like { from Order o in [g] select o.TotalAmount => Sum() }.
// In that case we need to ensure that the referenced query source [g] is demoted.
if (referencedQuerySource == null)
{
return;
}
// If the GroupResultOperator is not last (as captured by above)
// then we promote first GroupResultOperator to fall through streaming group by
var firstGroupResultOperator = queryModel.ResultOperators.OfType <GroupResultOperator>().FirstOrDefault();
if (firstGroupResultOperator != null)
{
PromoteQuerySource(firstGroupResultOperator);
}
var unreachableFromParentSelector =
isSubQuery && _querySourceTracingExpressionVisitor
.FindResultQuerySourceReferenceExpression(
_queryModelStack.Peek().SelectClause.Selector,
referencedQuerySource) == null;
if (finalResultOperator is SingleResultOperator ||
finalResultOperator is FirstResultOperator ||
finalResultOperator is LastResultOperator)
{
// If not a subquery or if reachable from the parent selector
// we would not want to fall through to one of the next blocks.
if (unreachableFromParentSelector)
{
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
}
return;
}
if (ConvergesToSingleValue(queryModel)
// This is to preserve QuerySource from MainFromClause when selector is ConstantExpression
// Since we would cause client evaluation from ConstantExpression.
// TODO: See #11215
&& !(queryModel.SelectClause.Selector is ConstantExpression))
{
// This is a top-level query that was not Single/First/Last
// but returns a single/scalar value (Avg/Min/Max/etc.)
// or a subquery that belongs to some outer-level query that returns
// a single or scalar value. The referenced query source should be
// re-promoted later if necessary.
// For top-level Contains we cannot translate it since Item is not Expression
if (!isSubQuery && finalResultOperator is ContainsResultOperator containsResultOperator)
{
return;
}
// If we are selecting from Grouping source but it is not GroupByAggregate Query
// then do not demote Grouping source since we still need to create groups.
if (referencedQuerySource.ItemType.IsGrouping() &&
!IsGroupByAggregateSubQuery(queryModel))
{
return;
}
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
return;
}
if (isSubQuery && (unreachableFromParentSelector || finalResultOperator is DefaultIfEmptyResultOperator))
{
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
}
}
/// <summary>
/// This API supports the Entity Framework Core infrastructure and is not intended to be used
/// directly from your code. This API may change or be removed in future releases.
/// </summary>
protected override Expression VisitSubQuery(SubQueryExpression expression)
{
var oldParentSelector = _selector;
var oldQueryModel = _queryModel;
_selector = expression.QueryModel.SelectClause.Selector;
_queryModel = expression.QueryModel;
_queryModel.TransformExpressions(Visit);
_selector = oldParentSelector;
_queryModel = oldQueryModel;
var querySourceReferenceExpression
= expression.QueryModel.SelectClause.Selector
as QuerySourceReferenceExpression;
if (querySourceReferenceExpression != null)
{
var querySourceTracingExpressionVisitor = new QuerySourceTracingExpressionVisitor();
if (expression.QueryModel.ResultOperators.LastOrDefault() is DefaultIfEmptyResultOperator)
{
var underlyingQuerySource = (((querySourceReferenceExpression.ReferencedQuerySource as MainFromClause)
?.FromExpression as QuerySourceReferenceExpression)
?.ReferencedQuerySource as GroupJoinClause)?.JoinClause;
if (underlyingQuerySource != null)
{
AddQuerySource(underlyingQuerySource);
}
}
var resultQuerySource
= querySourceTracingExpressionVisitor
.FindResultQuerySourceReferenceExpression(
_selector,
querySourceReferenceExpression.ReferencedQuerySource);
if ((resultQuerySource == null) &&
!(expression.QueryModel.ResultOperators.LastOrDefault() is OfTypeResultOperator))
{
_querySources[querySourceReferenceExpression.ReferencedQuerySource]--;
}
foreach (var sourceExpression
in _queryModel.ResultOperators.Select(SetResultOperationSourceExpression).Where(e => e != null))
{
if (sourceExpression.Equals(expression))
{
var parentQuerySource = _selector as QuerySourceReferenceExpression;
if ((parentQuerySource != null) &&
(_querySources[parentQuerySource.ReferencedQuerySource] > 0) &&
(parentQuerySource.Type == querySourceReferenceExpression.Type))
{
_querySources[querySourceReferenceExpression.ReferencedQuerySource]++;
}
}
}
}
return(expression);
}
private void AdjustForResultOperators(QueryModel queryModel)
{
var referencedQuerySource
= queryModel.SelectClause.Selector.TryGetReferencedQuerySource()
?? queryModel.MainFromClause.FromExpression.TryGetReferencedQuerySource();
// The selector may not have been a QSRE but this query model may still have something that needs adjusted.
// Example:
// context.Orders.GroupBy(o => o.CustomerId).Select(g => new { g.Key, g.Sum(o => o.TotalAmount) })
// The g.Sum(...) will result in a subquery model like { from Order o in [g] select o.TotalAmount => Sum() }.
// In that case we need to ensure that the referenced query source [g] is demoted.
if (referencedQuerySource == null)
{
return;
}
var isSubQuery = _queryModelStack.Count > 0;
var finalResultOperator = queryModel.ResultOperators.LastOrDefault();
if (isSubQuery && finalResultOperator is GroupResultOperator)
{
// These two lines should be uncommented to implement GROUP BY translation.
//DemoteQuerySource(referencedQuerySource);
//DemoteQuerySource(groupResultOperator);
return;
}
var unreachableFromParentSelector =
isSubQuery && _querySourceTracingExpressionVisitor
.FindResultQuerySourceReferenceExpression(
_queryModelStack.Peek().SelectClause.Selector,
referencedQuerySource) == null;
if (finalResultOperator is SingleResultOperator ||
finalResultOperator is FirstResultOperator ||
finalResultOperator is LastResultOperator)
{
// If not a subquery or if reachable from the parent selector
// we would not want to fall through to one of the next blocks.
if (unreachableFromParentSelector)
{
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
}
return;
}
if (ConvergesToSingleValue(queryModel))
{
// This is a top-level query that was not Single/First/Last
// but returns a single/scalar value (Avg/Min/Max/etc.)
// or a subquery that belongs to some outer-level query that returns
// a single or scalar value. The referenced query source should be
// re-promoted later if necessary.
// For top-level Contains we cannot translate it since Item is not Expression
if (!isSubQuery && finalResultOperator is ContainsResultOperator containsResultOperator)
{
return;
}
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
return;
}
if (isSubQuery && (unreachableFromParentSelector || finalResultOperator is DefaultIfEmptyResultOperator))
{
DemoteQuerySourceAndUnderlyingFromClause(referencedQuerySource);
}
}
