laravel ColumnDefinition类中的方法在哪里实现？

Question

To write migrations in laravel, we have different methods to apply them to our $table columns. One of them, for example, is nullable() which makes that column nullable.

I want to know, where do functions like nullable() have been defined. I cannot see anything such as public function nullable() in laravel. This must be in one of these classes but I can not find it:

1) vendor\laravel\framework\src\Illuminate\Database\Schema\ColumnDefinition

2) vendor\laravel\framework\src\Illuminate\Support\Fluent

3) vendor\laravel\framework\src\Illuminate\Database\Schema\Blueprint

or any other class extended from these or any other trait used in one of these.

Where do these functions have been defined?

Answer 1

The method nullable itself does not exist. If you take a look at the Blueprint class, the addColumn method returns an instance of ColumnDefinition.

And ColumnDefinition is an empty class which simply extends the Fluent class that contains the following __call method:

/**
 * Handle dynamic calls to the fluent instance to set attributes.
 *
 * @param  string  $method
 * @param  array   $parameters
 * @return $this
 */
public function __call($method, $parameters)
{
    $this->attributes[$method] = count($parameters) > 0 ? $parameters[0] : true;

    return $this;
}

Therefore, when you execute $table->string('name')->nullable();, it goes into the __call because the nullable method does not exist and simply saves the nullable attribute to true. Which also translates to:

$this->attributes['nullable'] = true;

And then in the MySqlGrammar class, it checks if the column is nullable or not:

/**
 * Get the SQL for a nullable column modifier.
 *
 * @param  \Illuminate\Database\Schema\Blueprint  $blueprint
 * @param  \Illuminate\Support\Fluent  $column
 * @return string|null
 */
protected function modifyNullable(Blueprint $blueprint, Fluent $column)
{
    if (is_null($column->virtualAs) && is_null($column->storedAs)) {
        return $column->nullable ? ' null' : ' not null';
    }
}

For more information about __call: https://www.php.net/manual/en/language.oop5.overloading.php#object.call