cannot query on strings in v5

System.NotSupportedException: "Method CompareString not available to convert to BsonExpression (CompareString(x.Name, value(testLiteDB.MainWindow+_Closure$__0-0).$VB$Local_customer.Name, False))."

how to reproduce: just perform any kind of query (Query/Find/FindOne) on a string property, using Lambda-Epressions. works in v4.

[lbnascimento]

@BangL In C#, the equality operator is a “real” operator and the BsonMapper successfully converts it to a to an expression. However, in VB, the string equality operator is converted to a call to CompareString, and the BsonMapper doesn’t know what to do with it.

In previous versions of LiteDB, lambdas that were not sucessfully converted to expressions were stored and executed after the results were retrieved and mapped to object. However, this feature was removed in v5 due to performance issues - if you ran your query on a collection with 1 million entries, all of them would be retrieved before the lambda expression was executed, which is very inefficient.

This feature may be recreated in v5.1 in a more efficient way, however please note that there might be a significant performance hit.

[BangL]

very good to know. thanks for the explanation! for me personally this problem is solved then, i will go BsonExpressions only from now on.

because of the performance issues and the vb.net incompatiblity, i would suggest putting the [ObsoleteAttribute] onto the lambda overloads though.