/// <summary>
/// Update documents using transform expression (must return a scalar/document value) using predicate as filter
/// </summary>
public int UpdateMany(string collection, BsonExpression transform, BsonExpression predicate)
{
if (collection.IsNullOrWhiteSpace())
{
throw new ArgumentNullException(nameof(collection));
}
if (transform == null)
{
throw new ArgumentNullException(nameof(transform));
}
return(this.Update(collection, transformDocs()));
IEnumerable <BsonDocument> transformDocs()
{
var q = new Query {
Select = "$", ForUpdate = true
};
if (predicate != null)
{
q.Where.Add(predicate);
}
using (var reader = this.Query(collection, q))
{
while (reader.Read())
{
var doc = reader.Current.AsDocument;
var id = doc["_id"];
var value = transform.ExecuteScalar(doc, _header.Pragmas.Collation);
if (!value.IsDocument)
{
throw new ArgumentException("Extend expression must return a document", nameof(transform));
}
var result = BsonExpressionMethods.EXTEND(doc, value.AsDocument).AsDocument;
// be sure result document will contain same _id as current doc
if (result.TryGetValue("_id", out var newId))
{
if (newId != id)
{
throw LiteException.InvalidUpdateField("_id");
}
}
else
{
result["_id"] = id;
}
yield return(result);
}
}
}
}