[jdbc-v2] incorrect wasNull flag for Array

[Onajk]

Describe the bug

After switching to jdbc-v2 there is a problem of reading Array right after NULL value. After debugging I have discovered that result set of array has wasNull flag set to True which is creating exception on Doobie side which I use to read data from ClickHouse in Scala code.

Steps to reproduce

1. "SELECT NULL, ['value1', 'value2']"
2. Check result set for second column (array)

Expected behaviour

In jdbc-v1 for version 0.7.2 there is no wasNull = true flag for that array and I would expect the same for jdbc-v2 for version 0.8.x

Code example

Statement stmt = conn.createStatement();
stmt.executeQuery("""
        SELECT NULL, ['value1', 'value2']
        """);
ResultSet rs = stmt.getResultSet();

And analyze the ResultSet (I don't know the methods since I was checking it in Scala)

Error log

Doobie is returning me NonNullableColumnRead error saying SQL 'NULL' read at column 2 (JDBC type Array) but mapping is to a non-Option type.
I have checked that this error is happening because wasNull flag was True after reading the array. By checking result set I could tell that it has correctly detected that first column is Null and second is array of two String values.

Configuration

"com.clickhouse" % "clickhouse-jdbc" % "0.8.2"

[Onajk]

Maybe forgot to update wasNull flag here?
https://github.com/ClickHouse/clickhouse-java/blob/main/jdbc-v2/src/main/java/com/clickhouse/jdbc/ResultSetImpl.java#L1024

[chernser]

Good day, @Onajk!
Thank you for reporting! We will look into it.

[mzitnik]

Hi @Onajk
I have added a test to try to reproduce the issue. See #2295
Can you confirm that we are referring to the same issue
Feedback will be appreciated.

[Onajk]

Hi, you didn't actually read the value of wasNull flag after reading the array. For me driver also reads all the data correctly but the flag is true for wasNull which gives me NonNullableColumnRead from Doobie. Value for array wasn't null so flag should be false after reading the array.

[Onajk]

One thing I forgot to mention. ClickHouse version I use is: ver. 24.3.12.76

[mzitnik]

@Onajk I made some adjustments.

[Onajk]

I believe that's it. Thank you