Inserting Null into a Table on Android using Bound Parameters inserts the String "NULL" instead.

Greetings,

Whenever you attempt to insert a NULL value as a column on a table on an Android device, a String of "NULL" gets inserted instead.

For example, consider the behavior of the following test case.

db.transaction((tx) => {
  tx.executeSql('CREATE TABLE IF NOT EXISTS null_test (id INTEGER PRIMARY KEY, value STRING)', []);
  tx.executeSql('INSERT INTO null_test (value) VALUES (?)', [null]);
  tx.executeSql('SELECT value FROM null_test', [],
    (_, result) => {
      const { rows } = result;
      for (let i = 0; i < rows.length; i += 1) {
        const item = rows.item(i);
        console.log(i, item); // 0 {value: "NULL"}
      }
    });
  tx.executeSql('SELECT COUNT(*) as count FROM null_test WHERE value IS NULL', [],
    (_, result) => {
      const { rows } = result;
      for (let i = 0; i < rows.length; i += 1) {
        const item = rows.item(i);
        console.log(i, item); // 0 {count: 0}
      }
  });
  tx.executeSql('DROP TABLE IF EXISTS null_test', []);
});

One would expect the answers to be {value: null} and {count: 1} instead. This issue, ultimately, stems from the convertParamsToStringArray function, and more specifically it’s use in the doUpdateInBackgroundAndPossiblyThrow method.

This is also an issue in the original cordova plugin. Ultimately the cause of the issue is the API provided by Android’s SQLite library. The compileStatement method allows for the binding of individual parameters, but it doesn’t allow for a variable length SELECT statement. Instead, in order to evaluate arbitrary SQL statements for SELECT statements rawQuery must be used. rawQuery only allows for a String[] as bound arguments. As such, it’s certainly influenced the decision to use convertParamsToStringArray in both places.

The fix is relatively straight forward, since the plugin is using compileStatement and that allows for individual parameters to be bound, we can just do that, and resolve the issue automatically.

It would likely still be an issue for binding NULL in a SELECT statement, but it’s not as a likely for that to occur, and I’m not certain how one gets around that while using any query method.

Thanks for your time, and the plugin,

Expect a Pull Request Shortly,

Thanks,

~ Ayiga

[Ash-faq]

How can i use Pre-populated SQLite database from my app

[alitsvin]

We still have this issue.