private void TranslateSelect(SelectExpression node)
{
Translate(node.Source);
var projectValue = TranslateProjectValue(node.Selector);
_stages.Add(new BsonDocument("$project", projectValue));
}
protected internal virtual Expression VisitSelect(SelectExpression node)
{
return node.Update(
Visit(node.Source),
Visit(node.Selector));
}
private BsonValue TranslateSelect(SelectExpression node)
{
var inputValue = TranslateValue(node.Source);
var inValue = TranslateValue(FieldNamePrefixer.Prefix(node.Selector, "$" + node.ItemName));
if (inputValue.BsonType == BsonType.String && inValue.BsonType == BsonType.String)
{
// if inputValue is a BsonString and inValue is a BsonString,
// then it is a simple field inclusion...
// inValue is prefixed with a $${node.ItemName}, so we remove the itemName and the 2 $s.
return inputValue.ToString() + inValue.ToString().Substring(node.ItemName.Length + 2);
}
return new BsonDocument("$map", new BsonDocument
{
{ "input", inputValue },
{ "as", node.ItemName },
{ "in", inValue}
});
}
private void VisitSelect(SelectExpression node)
{
Visit(node.Source);
var projection = AggregateProjectionTranslator.TranslateProject(node.Selector);
_stages.Add(new BsonDocument("$project", projection));
}
private BsonValue TranslateSelect(SelectExpression node)
{
if (node.Source is IFieldExpression && node.Selector is IFieldExpression)
{
var prefixName = ((IFieldExpression)node.Source).FieldName;
return TranslateValue(FieldNamePrefixer.Prefix(node.Selector, prefixName));
}
var inputValue = TranslateValue(node.Source);
var inValue = TranslateValue(FieldNamePrefixer.Prefix(node.Selector, "$" + node.ItemName));
return new BsonDocument("$map", new BsonDocument
{
{ "input", inputValue },
{ "as", node.ItemName },
{ "in", inValue}
});
}
protected internal virtual Expression VisitSelect(SelectExpression node)
{
return(node.Update(
Visit(node.Source),
Visit(node.Selector)));
}
