Asking the User for Confirmation

Suppose you want to confirm an action before actually executing it. Add the following to your command:

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// ...
if (!$dialog->askConfirmation(
        $output,
        '<question>Continue with this action?</question>',
        false
    )) {
    return;
}

In this case, the user will be asked "Continue with this action?", and will return true if the user answers with y or false if the user answers with n. The third argument to askConfirmation() is the default value to return if the user doesn't enter any input. Any other input will ask the same question again.

Asking the User for Information

You can also ask question with more than a simple yes/no answer. For instance, if you want to know a bundle name, you can add this to your command:

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// ...
$bundleName = $dialog->ask(
    $output,
    'Please enter the name of the bundle',
    'AcmeDemoBundle'
);

The user will be asked "Please enter the name of the bundle". They can type some name which will be returned by the ask() method. If they leave it empty, the default value (AcmeDemoBundle here) is returned.

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$dialog = $this->getHelper('dialog');
$bundleNames = array('AcmeDemoBundle', 'AcmeBlogBundle', 'AcmeStoreBundle');
$bundleName = $dialog->ask(
    $output,
    'Please enter the name of a bundle',
    'FooBundle',
    $bundleNames
);

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$dialog = $this->getHelper('dialog');
$password = $dialog->askHiddenResponse(
    $output,
    'What is the database password?',
    false
);

Validating the Answer

You can even validate the answer. For instance, in the last example you asked for the bundle name. Following the Symfony naming conventions, it should be suffixed with Bundle. You can validate that by using the askAndValidate() method:

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// ...
$bundleName = $dialog->askAndValidate(
    $output,
    'Please enter the name of the bundle',
    function ($answer) {
        if ('Bundle' !== substr($answer, -6)) {
            throw new \RuntimeException(
                'The name of the bundle should be suffixed with \'Bundle\''
            );
        }

        return $answer;
    },
    false,
    'AcmeDemoBundle'
);

This method has 2 new arguments, the full signature is:

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askAndValidate(
    OutputInterface $output,
    string|array $question,
    callback $validator,
    integer $attempts = false,
    string $default = null,
    array $autocomplete = null
)

The $validator is a callback which handles the validation. It should throw an exception if there is something wrong. The exception message is displayed in the console, so it is a good practice to put some useful information in it. The callback function should also return the value of the user's input if the validation was successful.

You can set the max number of times to ask in the $attempts argument. Using false means the amount of attempts is infinite. The user will be asked as long as they provide an invalid answer and will only be able to proceed if their input is valid.

Each time the user is asked the question, the default one is used if no answer is supplied (and validated with the $validator callback). If the last attempt is reached, the application will throw an exception and ends its execution.

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$dialog = $this->getHelper('dialog');

$validator = function ($value) {
    if ('' === trim($value)) {
        throw new \Exception('The password cannot be empty');
    }

    return $value;
};

$password = $dialog->askHiddenResponseAndValidate(
    $output,
    'Please enter your password',
    $validator,
    20,
    false
);

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$dialog = $this->getHelper('dialog');
$colors = array('red', 'blue', 'yellow');

$color = $dialog->select(
    $output,
    'Please select your favorite color (default to red)',
    $colors,
    0
);
$output->writeln('You have just selected: ' . $colors[$color]);

// ... do something with the color

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// ...

$selected = $dialog->select(
    $output,
    'Please select your favorite color (default to red)',
    $colors,
    0,
    false,
    'Value "%s" is invalid',
    true // enable multiselect
);

$selectedColors = array_map(function ($c) use ($colors) {
    return $colors[$c];
}, $selected);

$output->writeln(
    'You have just selected: ' . implode(', ', $selectedColors)
);

Testing a Command which Expects Input

If you want to write a unit test for a command which expects some kind of input from the command line, you need to overwrite the HelperSet used by the command:

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use Symfony\Component\Console\Application;
use Symfony\Component\Console\Helper\DialogHelper;
use Symfony\Component\Console\Helper\HelperSet;
use Symfony\Component\Console\Tester\CommandTester;

// ...
public function testExecute()
{
    // ...
    $application = new Application();
    $application->add(new MyCommand());
    $command = $application->find('my:command:name');
    $commandTester = new CommandTester($command);

    $dialog = $command->getHelper('dialog');
    $dialog->setInputStream($this->getInputStream("Test\n"));
    // Equals to a user inputting "Test" and hitting ENTER
    // If you need to enter a confirmation, "yes\n" will work

    $commandTester->execute(array('command' => $command->getName()));

    // $this->assertRegExp('/.../', $commandTester->getDisplay());
}

protected function getInputStream($input)
{
    $stream = fopen('php://memory', 'r+', false);
    fputs($stream, $input);
    rewind($stream);

    return $stream;
}

By setting the input stream of the DialogHelper, you imitate what the console would do internally with all user input through the cli. This way you can test any user interaction (even complex ones) by passing an appropriate input stream.