Verify SQLite Boolean column handling in Gradle and Maven projects

[zaleslaw]

Problem

Issue #1013 reports a SQLite Boolean-related problem in Kotlin Notebook:

• SQLite stores Boolean-like values as integers (0 / 1);
• generated property access expects Boolean;
• direct property access in Notebook can fail with:

ClassCastException: class java.lang.Integer cannot be cast to class java.lang.Boolean

The same report also mentions that in a regular IntelliJ/Gradle class, direct access fails earlier with:

Unresolved reference: is_active

That part may be a separate schema/accessor-generation issue rather than the same SQLite Boolean mapping problem.

We need to verify whether the actual SQLite Boolean conversion/casting issue is reproducible in regular Gradle and Maven projects when schema/accessor setup is configured correctly.

Goal

Check whether SQLite columns declared or inferred as Boolean are handled consistently outside Kotlin Notebook.

Scenarios to Verify

Gradle

Create or reuse a Gradle sample with:

• SQLite database containing a Boolean-like column stored as 0 / 1;
• JDBC/DataFrame read path;
• explicit schema or generated accessors;
• direct typed access to the Boolean column.

Verify whether:

df.is_active

or equivalent typed access works, fails with ClassCastException, or requires explicit conversion.

Maven

Repeat the same verification in a Maven project, if Maven support is expected for the same workflow.

Expected Behavior

One of the following should be clearly defined:

• SQLite 0 / 1 values are converted to Boolean when schema expects Boolean; or
• SQLite Boolean-like columns are read as Int, and users must convert them explicitly; or
• a clear diagnostic explains that SQLite does not have a native Boolean type and that 0 / 1 values cannot be accessed as Boolean without conversion.

The behavior should be consistent across Notebook, Gradle, and Maven where the same schema/accessor setup is available.

Definition of Done

• Verify the issue in a regular Gradle project.
• Verify the issue in a Maven project, if applicable.
• Document whether the Notebook failure from Kotlin Dataframe SQLite Integer cannot be cast to Boolean #1013 reproduces outside Notebook.
• If reproducible:
  • identify whether the problem is in JDBC type inference, schema/accessor generation, or row/property access;
  • add a minimal regression test or sample;
  • fix conversion or improve diagnostics.
• If not reproducible:
  • document why Kotlin Dataframe SQLite Integer cannot be cast to Boolean #1013 is Notebook-specific;
  • close or narrow Kotlin Dataframe SQLite Integer cannot be cast to Boolean #1013 accordingly.
• Link findings back to Kotlin Dataframe SQLite Integer cannot be cast to Boolean #1013.

Related

• Kotlin Dataframe SQLite Integer cannot be cast to Boolean #1013
• Stack Overflow report: https://stackoverflow.com/questions/79333504/kotlin-dataframe-sqlite-integer-cannot-be-cast-to-boolean-in-notebook
• SQLite type documentation: https://www.sqlite.org/datatype3.html