protected override ShapedQueryExpression TranslateGroupBy(
ShapedQueryExpression source,
LambdaExpression keySelector,
LambdaExpression elementSelector,
LambdaExpression resultSelector)
{
var selectExpression = (SelectExpression)source.QueryExpression;
selectExpression.PrepareForAggregate();
var remappedKeySelector = RemapLambdaBody(source.ShaperExpression, keySelector);
var translatedKey = TranslateGroupingKey(remappedKeySelector)
?? (remappedKeySelector is ConstantExpression ? remappedKeySelector : null);
if (translatedKey != null)
{
if (elementSelector != null)
{
source = TranslateSelect(source, elementSelector);
}
var sqlKeySelector = translatedKey is ConstantExpression
? _sqlExpressionFactory.ApplyDefaultTypeMapping(_sqlExpressionFactory.Constant(1))
: translatedKey;
var appliedKeySelector = selectExpression.ApplyGrouping(sqlKeySelector);
translatedKey = translatedKey is ConstantExpression ? translatedKey : appliedKeySelector;
source.ShaperExpression = new GroupByShaperExpression(translatedKey, source.ShaperExpression);
if (resultSelector == null)
{
return(source);
}
var keyAccessExpression = Expression.MakeMemberAccess(
source.ShaperExpression,
source.ShaperExpression.Type.GetTypeInfo().GetMember(nameof(IGrouping <int, int> .Key))[0]);
var newResultSelectorBody = ReplacingExpressionVisitor.Replace(
resultSelector.Parameters[0], keyAccessExpression,
resultSelector.Parameters[1], source.ShaperExpression,
resultSelector.Body);
source.ShaperExpression = _projectionBindingExpressionVisitor.Translate(selectExpression, newResultSelectorBody);
return(source);
}
throw new InvalidOperationException();
}
protected override ShapedQueryExpression TranslateSelect(ShapedQueryExpression source, LambdaExpression selector)
{
if (selector.Body == selector.Parameters[0])
{
return(source);
}
var newSelectorBody = ReplacingExpressionVisitor.Replace(selector.Parameters.Single(), source.ShaperExpression, selector.Body);
source.ShaperExpression = _projectionBindingExpressionVisitor
.Translate((SelectExpression)source.QueryExpression, newSelectorBody);
return(source);
}
