/// <summary>
/// Visits a query source reference expression.
/// </summary>
/// <param name="expression"> The expression to visit. </param>
/// <returns>
/// An Expression.
/// </returns>
protected override Expression VisitQuerySourceReference(QuerySourceReferenceExpression expression)
{
Check.NotNull(expression, nameof(expression));
if (!_inProjection)
{
var joinClause
= expression.ReferencedQuerySource as JoinClause;
if (joinClause != null)
{
var entityType
= _queryModelVisitor.QueryCompilationContext.Model
.FindEntityType(joinClause.ItemType);
if (entityType != null)
{
return(Visit(
EntityQueryModelVisitor.CreatePropertyExpression(
expression, entityType.FindPrimaryKey().Properties[0])));
}
return(null);
}
}
var type = expression.ReferencedQuerySource.ItemType.UnwrapNullableType().UnwrapEnumType();
if (_relationalTypeMapper.FindMapping(type) != null)
{
var selectExpression = _queryModelVisitor.TryGetQuery(expression.ReferencedQuerySource);
if (selectExpression != null)
{
var subquery = selectExpression.Tables.FirstOrDefault() as SelectExpression;
var innerProjectionExpression = subquery?.Projection.FirstOrDefault() as AliasExpression;
if (innerProjectionExpression != null)
{
if (innerProjectionExpression.Alias != null)
{
return(new ColumnExpression(
innerProjectionExpression.Alias,
innerProjectionExpression.Type,
subquery));
}
var newExpression = selectExpression.UpdateColumnExpression(innerProjectionExpression.Expression, subquery);
return(new AliasExpression(newExpression)
{
SourceMember = innerProjectionExpression.SourceMember
});
}
}
}
return(null);
}
private static Expression CreateKeyAccessExpression(Expression target, IReadOnlyList <IProperty> properties)
{
return(properties.Count == 1
? EntityQueryModelVisitor.CreatePropertyExpression(target, properties[0])
: Expression.New(
CompositeKey.CompositeKeyCtor,
Expression.NewArrayInit(
typeof(object),
properties
.Select(p => Expression.Convert(EntityQueryModelVisitor.CreatePropertyExpression(target, p), typeof(object)))
.Cast <Expression>()
.ToArray())));
}
private static Expression CreateKeyAccessExpression(Expression target, IReadOnlyList <IProperty> properties, bool nullComparison)
{
// If comparing with null then we need only first PK property
return((properties.Count == 1) || nullComparison
? EntityQueryModelVisitor.CreatePropertyExpression(target, properties[0])
: Expression.New(
CompositeKey.CompositeKeyCtor,
Expression.NewArrayInit(
typeof(object),
properties
.Select(p => Expression.Convert(EntityQueryModelVisitor.CreatePropertyExpression(target, p), typeof(object)))
.Cast <Expression>()
.ToArray())));
}