Osm Admin: Data Conversion Issues

Last time, I pushed through string property migrations and created a migration log.

Let's continue solving data conversion issues.

• Undefined Method Diff\Property\Int_::convert()
• Migration::$default_value
• test_make_explicit_property_non_nullable Doesn't Invoke Data Conversion
• Add a select expression to the query Error

Undefined Method Diff\Property\Int_::convert()

Indeed, I moved data conversion logic to new Migration\* classes, and didn't update the calling code.

Here it is updated:

// Osm\Admin\Schema\Diff\Table
protected function get_requires_convert(): bool {
    foreach ($this->properties as $property) {
        if ($property->requiresMigration(Property::CONVERT)) {
            return true;
        }
    }

    return false;
}

protected function convert(): void {
    $query = Query::new(['table' => $this->new]);

    if ($this->requires_convert) {
        $this->log(__("Converting ':table' table", [
            'table' => $this->new->table_name,
        ]));

        foreach ($this->properties as $property) {
            $property->convert($query);
        }

        $query->bulkUpdate();
    }
}

// Osm\Admin\Schema\Diff\Property
public function convert(Query $query): void {
    if (!$this->requiresMigration(static::CONVERT)) {
        return;
    }

    $new = "{$this->migration_class_name}::new";

    $new([
        'property' => $this,
        'mode' => static::CONVERT,
        'query' => $query,
    ])->migrate();
}

Migration::$default_value

The Migration::$default_value returns a value that should be assigned to a property if old value can't be converted, for example if a non-numeric string is converted to int.

It returns NULL for nullable properties, and a falsy value (0 for int, 0.0 for float, false for bool, '-' for string):

// Osm\Admin\Schema\Diff\Migration\String_
protected function get_default_value(): string {
    return $this->property->new->actually_nullable
        ? "NULL"
        : "'-'";
}

// Osm\Admin\Schema\Diff\Migration\Int_
protected function get_default_value(): string {
    return $this->property->new->actually_nullable
        ? "NULL"
        : "0";
}

test_make_explicit_property_non_nullable Doesn't Invoke Data Conversion

When a property becomes non-nullable, NULL should be converted to the default value.

However, no data conversion occurs. Why?

It turns out, the nullability handling didn't call the run() method, and the migration didn't think any conversion is needed.

The fix:

// Osm\Admin\Schema\Diff\Migration
protected function becomeNonNullable(): void {
    switch ($this->mode) {
        ...
        case Property::CONVERT:
            $this->new_value = "{$this->new_value} ?? $this->default_value";
            $this->run('nullable');
            break;
        ...
    }
}

Add a select expression to the query Error

The next thing that changed is that migration classes only prepare formulas for the data conversion query, but don't add them to the query.

Fix:

// Osm\Admin\Schema\Diff\Property
public function convert(Query $query): void {
    if (!$this->requiresMigration(static::CONVERT)) {
        return;
    }

    $new = "{$this->migration_class_name}::new";

    /* @var Migration $migration */
    $migration = $new([
        'property' => $this,
        'mode' => static::CONVERT,
        'query' => $query,
    ]);

    $migration->migrate();

    $formula = str_replace('{{old_value}}', $migration->old_value,
        $migration->new_value);
    $query->select("{$formula} AS {$this->new->name}");
}