private IWhereFragment buildChildCollectionQuery(IQueryableDocument mapping, QueryModel query, Expression valueExpression, string op) { var members = FindMembers.Determine(query.MainFromClause.FromExpression); var field = mapping.FieldFor(members); if (query.HasOperator<CountResultOperator>()) { var value = field.GetValue(valueExpression); return new WhereFragment($"jsonb_array_length({field.SqlLocator}) {op} ?", value); } throw new NotSupportedException("Marten does not yet support this type of Linq query against child collections"); }