/// <summary>
/// Visits a nest against a constant expression, which must be an IBucketQueryable implementation
/// </summary>
/// <param name="nestClause">Nest clause being visited</param>
/// <param name="constantExpression">Constant expression that is the InnerSequence of the NestClause</param>
/// <param name="itemName">Name to be used when referencing the data being nested</param>
/// <returns>N1QlFromQueryPart to be added to the QueryPartsAggregator</returns>
private N1QlFromQueryPart VisitConstantExpressionNestClause(NestClause nestClause, ConstantExpression constantExpression, string itemName)
{
string bucketName = null;
if (constantExpression != null)
{
var bucketQueryable = constantExpression.Value as IBucketQueryable;
if (bucketQueryable != null)
{
bucketName = bucketQueryable.BucketName;
}
}
if (bucketName == null)
{
throw new NotSupportedException("N1QL Nests Must Be Against IBucketQueryable");
}
return(new N1QlFromQueryPart()
{
Source = N1QlHelpers.EscapeIdentifier(bucketName),
ItemName = itemName,
OnKeys = GetN1QlExpression(nestClause.KeySelector),
JoinType = nestClause.IsLeftOuterNest ? "LEFT OUTER NEST" : "INNER NEST"
});
}
/// <summary>
/// Visits a nest against either a constant expression of IBucketQueryable, or a subquery based on an IBucketQueryable
/// </summary>
/// <param name="nestClause">Nest clause being visited</param>
/// <returns>N1QlFromQueryPart to be added to the QueryPartsAggregator</returns>
private N1QlFromQueryPart ParseNestClause(NestClause nestClause)
{
switch (nestClause.InnerSequence.NodeType)
{
case ExpressionType.Constant:
return(VisitConstantExpressionNestClause(nestClause, nestClause.InnerSequence as ConstantExpression,
GetExtentName(nestClause)));
case SubQueryExpression.ExpressionType: // SubQueryExpression
var subQuery = nestClause.InnerSequence as SubQueryExpression;
if ((subQuery == null) || subQuery.QueryModel.ResultOperators.Any() || subQuery.QueryModel.MainFromClause.FromExpression.NodeType != ExpressionType.Constant)
{
throw new NotSupportedException("Unsupported Nest Inner Sequence");
}
// Generate a temporary item name to use on the NEST statement, which we can then reference in the LET statement
var genItemName = _queryGenerationContext.ExtentNameProvider.GetUnlinkedExtentName();
var fromPart = VisitConstantExpressionNestClause(nestClause,
subQuery.QueryModel.MainFromClause.FromExpression as ConstantExpression, genItemName);
// Put any where clauses in the sub query in an ARRAY filtering clause using a LET statement
var whereClauseString = string.Join(" AND ",
subQuery.QueryModel.BodyClauses.OfType <WhereClause>()
.Select(p => GetN1QlExpression(p.Predicate)));
var letPart = new N1QlLetQueryPart()
{
ItemName = GetExtentName(nestClause),
Value =
string.Format("ARRAY {0} FOR {0} IN {1} WHEN {2} END",
GetExtentName(subQuery.QueryModel.MainFromClause),
genItemName,
whereClauseString)
};
_queryPartsAggregator.AddLetPart(letPart);
if (!nestClause.IsLeftOuterNest)
{
// This is an INNER NEST, but the inner sequence filter is being applied after the NEST operation is done
// So we need to put an additional filter to drop rows with an empty array result
_queryPartsAggregator.AddWherePart("(ARRAY_LENGTH({0}) > 0)", letPart.ItemName);
}
return(fromPart);
default:
throw new NotSupportedException("Unsupported Nest Inner Sequence");
}
}
public void VisitNestClause(NestClause nestClause, QueryModel queryModel, int index)
{
EnsureNotArraySubquery();
_queryPartsAggregator.AddFromPart(ParseNestClause(nestClause));
}
