internal ColumnExpression(ProjectionExpression subqueryProjection, TableExpressionBase table, bool nullable)
: this(subqueryProjection.Alias, table, subqueryProjection.Type, subqueryProjection.Expression.TypeMapping, nullable)
{
}
public void PushdownIntoSubQuery()
{
var subquery = Clone("t");
if (subquery.Limit == null && subquery.Offset == null)
{
subquery.ClearOrdering();
}
_projectionMapping.Clear();
var columnNameCounter = 0;
var index = 0;
var result = new Dictionary <ProjectionMember, Expression>();
foreach (var projection in subquery._projectionMapping)
{
result[projection.Key] = Constant(index);
if (projection.Value is EntityProjectionExpression entityProjection)
{
var propertyExpressions = new Dictionary <IProperty, ColumnExpression>();
foreach (var property in entityProjection.EntityType.GetProperties())
{
var innerColumn = entityProjection.GetProperty(property);
var projectionExpression = new ProjectionExpression(innerColumn, innerColumn.Name);
subquery._projection.Add(projectionExpression);
propertyExpressions[property] = new ColumnExpression(projectionExpression, subquery, innerColumn.Nullable);
index++;
}
_projectionMapping[projection.Key] = new EntityProjectionExpression(
entityProjection.EntityType, propertyExpressions);
}
else
{
var projectionExpression = new ProjectionExpression(
(SqlExpression)projection.Value, "c" + columnNameCounter++);
subquery._projection.Add(projectionExpression);
_projectionMapping[projection.Key] = new ColumnExpression(
projectionExpression, subquery, IsNullableProjection(projectionExpression));
index++;
}
}
subquery._projectionMapping = result;
var currentOrderings = _orderings.ToList();
_orderings.Clear();
foreach (var ordering in currentOrderings)
{
var orderingExpression = ordering.Expression;
var innerProjection = subquery._projection.FirstOrDefault(
pe => pe.Expression.Equals(orderingExpression));
if (innerProjection != null)
{
_orderings.Add(new OrderingExpression(new ColumnExpression(innerProjection, subquery, IsNullableProjection(innerProjection)), ordering.Ascending));
}
else
{
var projectionExpression = new ProjectionExpression(ordering.Expression, "c" + columnNameCounter++);
subquery._projection.Add(projectionExpression);
_orderings.Add(new OrderingExpression(
new ColumnExpression(projectionExpression, subquery, IsNullableProjection(projectionExpression)), ordering.Ascending));
}
}
Offset = null;
Limit = null;
IsDistinct = false;
Predicate = null;
_tables.Clear();
_tables.Add(subquery);
}
private static bool IsNullableProjection(ProjectionExpression projection)
{
return(projection.Expression is ColumnExpression column ? column.Nullable : true);
}
private static bool IsNullableProjection(ProjectionExpression projectionExpression)
=> projectionExpression.Expression switch
{
