Dynamically generate PHP static methods to instantiate new object

user_16145046 0
Viewed 35

I am trying to build a database-class that allows method chaining to query it. I want to instantiate it like Laravel's Eloquent by making the first call static.

See this example:

class Database
{
    public function construct($data) {
        $this->data = $data;
    }
    public function filter($criteria) {
        // ...
        return $this;
    }
    public static function filter($data, $criteria) {
        $obj = new Database($data);
        $obj->filter($criteria);
        return $obj;
    }
    public function add($value) {
        // ...
        return $this;
    }
    public static function add($data, $value,) {
        $obj = new Database($data);
        $obj->add($value);
        return $obj;
    }
}

This would allow me for example:

Database::add($myData, $newValue)->add($anotherValue)->filter('isString');
Database::filter($myData, 'isNumber')->add($thirdValue);

This is not supposed to be the real thing, but I am curious if there was a way to reduce the duplicated code throughout my static methods or to remove them entirely. I thought of the magic method __callStatic() but I am not sure if it is the best way to achieve it.

I would appreciate it if someone who knows could explain me, how big frameworks deal with this kind of task.

static-methods instantiation php
2 Answers

Yea it is indeed done through magic method __callStatic().

Here you have Laravel Eloquent code snippets, these are taken from Model class, there is more things going on, but these are relevant to your case:

public static function __callStatic($method, $parameters)
{
    return (new static)->$method(...$parameters); // delegating to __call method
}

public function __call($method, $parameters)
{
    ...
    // self explanatory
    return $this->forwardCallTo($this->newQuery(), $method, $parameters);
}

// newQuery method lead to this method:
public function newModelQuery()
{
    return $this->newEloquentBuilder(
        $this->newBaseQueryBuilder() // deals with getting database connection
    )->setModel($this);
}

// newEloquentBuilder return Builder class which have the "where" etc. methods defined.

In your case simple example:

class Database
{
    protected static $connection;
    protected $query; // could be array or better object

    public function __construct() {
        if(!static::$connection){
            static::$connection = new mysqli(...); // for example
        }
    }
    
    public static function __callStatic($method, $parameters)
    {
        return (new static)->$method(...$parameters);
    }
    
    // in case $query is object have these two methods defined there
    // also delegate with __call method to the query object
    
    public function filter($criteria) {
        ... // filling $query variable
        return $this;
    }
  
    public function add($value) {
        ... // filling $query variable
        return $this;
    }
    
    public function fetch_assoc() {
        $stmt = static::$connection->prepare(...);
        ... // fill the prepared statements with $query data
        return $stmt->get_result()->fetch_assoc();
    }
}
user_70284320

You can use static methods from object, but you cannot use $this in that method.

You cannot define static and not static methods with the same name.

In most cases I need only the not static method, and in rare case I don't have an object instance I instantiate just for this method call - and call the non-static method.

In rare cases I define the static method too with different name, for example filterStatic(). This is a very rare case, and in this case the non-static method wraps the static one to avoid code duplication.

user_74742340
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