/// <summary>
/// Visits a SqlAliasedCollectionExpression and transforms the documents accordingly.
/// </summary>
/// <param name="collectionExpression">The collection expression to visit.</param>
/// <param name="documents">The documents to transform.</param>
/// <returns>The transformed documents according to the collection expression.</returns>
public override IEnumerable <CosmosElement> Visit(SqlAliasedCollectionExpression collectionExpression, IEnumerable <CosmosElement> documents)
{
//If the query was:
//SELECT *
//FROM c
//and the document was:
//{
// "name" : "John"
//}
//Then this function would return:
//{
// "c" : { "name" : "John" }
//}
//which is just wrapping the original document in the identifier.
// Get the sub collection
CollectionEvaluationResult collectionEvaluationResult = collectionExpression.Collection.Accept(
SqlInterpreterCollectionVisitor.Singleton,
documents);
string identifer = collectionEvaluationResult.Identifer;
// Figure out what the alias should be
int aliasCounter = 0;
string alias;
if (collectionExpression.Alias != null)
{
alias = collectionExpression.Alias.Value;
}
else if (identifer != null)
{
alias = identifer;
}
else
{
alias = $"#{aliasCounter++}";
}
// Wrap the collection in the alias so it's easier to bind later
foreach (Tuple <CosmosElement, string> subDocumentAndRid in collectionEvaluationResult.SubDocumentsAndRids)
{
Dictionary <string, CosmosElement> wrappedDocument = new Dictionary <string, CosmosElement>
{
[alias] = subDocumentAndRid.Item1,
//// Add the _rid so that we can break ties for sort later
["_rid"] = CosmosString.Create(subDocumentAndRid.Item2)
};
yield return(CosmosObject.Create(wrappedDocument));
}
}
/// <summary>
/// Visits a SqlArrayIteratorCollectionExpression and transforms the documents accordingly.
/// </summary>
/// <param name="collectionExpression">The collection expression to visit.</param>
/// <param name="documents">The documents to transform.</param>
/// <returns>The transformed documents according to the collection expression.</returns>
public override IEnumerable <CosmosElement> Visit(SqlArrayIteratorCollectionExpression collectionExpression, IEnumerable <CosmosElement> documents)
{
//If the query was:
//SELECT p
//FROM p in c.parents
//and the document was
//{
// "parents" : [{"name" : "John"}, {"name" : "Sally"}]
//}
//then the results would be:
//{ "p" : {"name" : "John"} }
//and
//{ "p" : {"name" : "Sally"} }
//Notice that the result set is larger than the input
//This is because we emitted one document for each parent in the original document
//and wrapped it in the provided alias.
// throw away the identifer since we always have an alias
CollectionEvaluationResult collectionEvaluationResult = collectionExpression.Collection.Accept(
SqlInterpreterCollectionVisitor.Singleton,
documents);
// Wrap the collection in the alias so it's easier to bind later
foreach (Tuple <CosmosElement, string> subDocumentAndRid in collectionEvaluationResult.SubDocumentsAndRids)
{
CosmosElement document = subDocumentAndRid.Item1;
string rid = subDocumentAndRid.Item2;
if (document is CosmosArray array)
{
foreach (CosmosElement item in array)
{
Dictionary <string, CosmosElement> wrappedDocument = new Dictionary <string, CosmosElement>
{
[collectionExpression.Identifier.Value] = item,
//// Add the _rid so that we can break ties for sort later
["_rid"] = CosmosString.Create(rid),
};
yield return(CosmosObject.Create(wrappedDocument));
}
}
}
}
