Unexpected panic/unwrap when retrieving null value from database

[SSC-PuA]

When retrieving data from the database I get this error if there is a null – tried with bool, i32, i64m double and worked fine – issue only with string.

RUST_BACKTRACE=1 cargo run
    Finished debug [unoptimized + debuginfo] target(s) in 0.0 secs
     Running `target/debug/cassandra-connector`
thread 'main' panicked at 'called `Result::unwrap()` on an `Err` value: Error(LIB_NULL_VALUE(CASS_ERROR_LIB_NULL_VALUE), State { next_error: None, backtrace: Some(stack backtrace:
   0:     0x7fe28e3f0401 - backtrace::backtrace::libunwind::trace
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.0/src/backtrace/mod.rs:90
                         - backtrace::backtrace::trace<closure>
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.0/src/backtrace/mod.rs:42
   1:     0x7fe28e3f1408 - backtrace::capture::{{impl}}::new
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/backtrace-0.3.0/src/lib.rs:101
   2:     0x7fe28e3e82c1 - error_chain::make_backtrace
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.7.2/src/lib.rs:411
   3:     0x7fe28e3e8377 - error_chain::{{impl}}::default
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/error-chain-0.7.2/src/lib.rs:462
   4:     0x7fe28e2b464b - cassandra_sys::error::{{impl}}::from_kind
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-sys-0.8.7/src/error.rs:6
   5:     0x7fe28e2b4841 - cassandra_sys::error::{{impl}}::from
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-sys-0.8.7/src/error.rs:6
   6:     0x7fe28e2aaf51 - core::convert::{{impl}}::into<cassandra_sys::error::ErrorKind,cassandra_sys::error::Error>
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/convert.rs:271
   7:     0x7fe28e2a0be9 - cassandra_sys::error::{{impl}}::to_result<&str>
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-sys-0.8.7/src/error.rs:133
   8:     0x7fe28e2b17c9 - cassandra::cassandra::column::{{impl}}::get_string
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-0.8.1/src/cassandra/column.rs:270
   9:     0x7fe28e299e65 - cassandra_connector::show
                        at /home/proj/cassandra-connector/src/main.rs:38
  10:     0x7fe28e29ab19 - cassandra_connector::main
                        at /home/proj/cassandra-connector/src/main.rs:76
  11:     0x7fe28e4095ca - panic_unwind::__rust_maybe_catch_panic
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libpanic_unwind/lib.rs:98
  12:     0x7fe28e4031b6 - std::panicking::try<(),fn()>
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:434
                         - std::panic::catch_unwind<fn(),()>
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panic.rs:351
                         - std::rt::lang_start
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/rt.rs:57
  13:     0x7fe28e29b042 - main
  14:     0x7fe28c8f0b34 - __libc_start_main
  15:     0x7fe28e28d3e8 - <unknown>
  16:                0x0 - <unknown>) })', /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/result.rs:837
stack backtrace:
   1:     0x7fe28e4008fa - std::sys::imp::backtrace::tracing::imp::write::h3188f035833a2635
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/sys/unix/backtrace/tracing/gcc_s.rs:42
   2:     0x7fe28e40286f - std::panicking::default_hook::{{closure}}::h6385b6959a2dd25b
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:349
   3:     0x7fe28e40246e - std::panicking::default_hook::he4f3b61755d7fa95
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:365
   4:     0x7fe28e402cb7 - std::panicking::rust_panic_with_hook::hf00b8130f73095ec
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:553
   5:     0x7fe28e402af4 - std::panicking::begin_panic::h6227f62cb2cdaeb4
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:515
   6:     0x7fe28e402a69 - std::panicking::begin_panic_fmt::h173eadd80ae64bec
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:499
   7:     0x7fe28e4029f7 - rust_begin_unwind
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:475
   8:     0x7fe28e4331ed - core::panicking::panic_fmt::h3b2d1e30090844ff
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/panicking.rs:69
   9:     0x7fe28e2aa215 - core::result::unwrap_failed::h6f1089a4164b68db
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/macros.rs:29
  10:     0x7fe28e2a58bb - <core::result::Result<T, E>>::unwrap::hddf0ca9c49ea9914
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libcore/result.rs:737
  11:     0x7fe28e2b187a - cassandra::cassandra::column::Column::get_string::he370ca9df985f0ee
                        at /opt/rust/.cargo/registry/src/github.com-1ecc6299db9ec823/cassandra-0.8.1/src/cassandra/column.rs:270
  12:     0x7fe28e299e65 - cassandra_connector::show::hb977a687937c57f0
                        at /home/proj/cassandra-connector/src/main.rs:38
  13:     0x7fe28e29ab19 - cassandra_connector::main::h0159580624f528ae
                        at /home/proj/cassandra-connector/src/main.rs:76
  14:     0x7fe28e4095ca - __rust_maybe_catch_panic
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libpanic_unwind/lib.rs:98
  15:     0x7fe28e4031b6 - std::rt::lang_start::h65647f6e36cffdae
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panicking.rs:434
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/panic.rs:351
                        at /buildslave/rust-buildbot/slave/stable-dist-rustc-linux/build/src/libstd/rt.rs:57
  16:     0x7fe28e29b042 - main
  17:     0x7fe28c8f0b34 - __libc_start_main
  18:     0x7fe28e28d3e8 - <unknown>
  19:                0x0 - <unknown>

I was hoping that the program would panic with the message “Bad string value! Error message….” As it does with other data types. (for the other types in the database it worked as expected: bool, i32, i62, double)

#[macro_use(stmt)]

extern crate cassandra;
use cassandra::*;
use std::str::FromStr;
#[derive(Debug,PartialEq,Clone,Copy)]
struct Basic {
    bln: bool,
    flt: f32,
    dbl: f64,
    i32: i32,
    i64: i64,
}
fn insert_into_basic(session: &mut Session, key: &str, basic: Basic) -> CassResult {
    let mut statement = stmt!("INSERT INTO examples.basic (key, bln, flt, dbl, i32, i64) VALUES \
                               (?, ?, ?, ?, ?, ?);");
    statement.bind(0, key);
    statement.bind(1, basic.bln);
    statement.bind(2, basic.flt);
    statement.bind(3, basic.dbl);
    statement.bind(4, basic.i32);
    statement.bind(5, basic.i64);
    let res = session.execute(&statement).wait().unwrap();
    res
}
fn select_all(session: &mut Session) -> CassResult {
    let stmt = stmt!("SELECT * FROM examples.basic");
    let result = match session.execute(&stmt).wait() {
        Result::Ok(val) => val,
        Result::Err(err) => panic!("Bad select! {}", err),
    };
    result
}
fn show(data: &CassResult) {
    for i in data.iter() {
        match i.get_column(5) {
            Result::Ok(val) => {
                match val.get_string() {
                    Result::Ok(s) => println!("{:?}", s),
                    Result::Err(err) => {
                        panic!("Bad string value! {}", err);
                    }
               }
            }
            Result::Err(err) => panic!("Bad column! {}", err),
        };
    }
}
fn main() {
    let input = Basic {
        bln: true,
        flt: 0.001f32,
        dbl: 0.0002f64,
        i32: 1,
        i64: 2,
    };
    let contact_points = match ContactPoints::from_str("127.0.0.1") {
        Result::Ok(val) => val,
        Result::Err(err) => panic!("My error! {}", err),
    };
    let mut cluster = Cluster::default();
    cluster.set_contact_points(contact_points).unwrap();
    cluster.set_load_balance_round_robin();
    match cluster.connect() {
        Ok(ref mut session) => {
            let ks_statement = &stmt!("CREATE KEYSPACE IF NOT EXISTS examples WITH replication = \
                                       { \'class\': \'SimpleStrategy\', \'replication_factor\': \
                                       \'1\' };");
            let table_statement = &stmt!("CREATE TABLE IF NOT EXISTS examples.basic (key text, \
                                          bln boolean, flt float, dbl double, i32 int, i64 \
                                          bigint, PRIMARY KEY (flt));");
            session.execute(ks_statement).wait().unwrap();
            session.execute(table_statement).wait().unwrap();
            insert_into_basic(session, "test", input);
            let output = select_all(session);
            show(&output);
            println!("{:?}", input);
            // println!("{:?}", output);
        }
        err => println!("{:?}", err),
    }
}