Determine if an attribute exists on the object.

@param string $key
@return bool
4839
public function __isset($key)
	{
		if (isset($this->$key) && (!is_null($this->$key))) {
			return true;
		}
		if (!isset($this->specificationExtensions[$key])) {
			return false;
		}
		return !is_null($this->specificationExtensions[$key]);
	}
1272101
public function exists( $key ) {
		return ( is_array( $this->data ) && array_key_exists( $key, $this->data ) ) ||
			( is_object( $this->data ) && property_exists( $this->data, $key ) );
	}
148906
public function has($key)
    {
        $result = array_key_exists($key, $this->data);
        if (!$result && $this->isDotNotation($key)) {
            $result = true;
            $keys = explode('.', $key);
            $data = $this->data;

            foreach ($keys as $key) {
                if (!is_array($data) || !array_key_exists($key, $data)) {
                    $result = false;
                    break;
                }

                $data = $data[$key];
            }
        }

        return $result;
    }
335875
public function isEntityAttribute(string $key)
    {
        $key = $this->getEntityAttributeName($key);

        return $this->getEntityAttributes()->has($key);
    }
441548
public function has(string $key): bool
    {
        if (!array_key_exists($key, $this->data)) {
            return false;
        }

        return true;
    }
757897
public function has( $key )
	{
		$key	= !$this->caseSensitive ? strtolower( $key ) : $key;								//  lowercase key if dictionary is not case sensitive
		return array_key_exists( $key, $this->pairs );
	}
619117
public function exist($key) : bool
    {
        return $this->get($key, false) !== false
               && $this->get($key, true) !== true;
    }
972886
public function ifExists(string $key): bool
    {
        if ($this->get($key) === false) {
            return false;
        }

        return true;
    }
728388
public static function exists($key)
    {
        $key = explode('.', $key);
        $array = self::$arr[$key[0]];
        unset($key[0]);

        foreach ( $key as $k ) {
            if ( is_array(self::$arr) ) {
                $array = $array[$k];
            } else {
                return false;
            }
        }

        if ( !is_null($array) ) {
            return true;
        } else {
            return false;
        }
    }
994593
public function __isset($key)
    {
        return (isset($this->attributes[$key]) && null !== $this->getAttributeValue($key));
    }
946653
public function exists(string $key): bool
    {
        $driver = $this->getDriver();
        $exists = $driver->get($key) !== null;
        if ($this->hasEventListeners('itemExists')) {
            $this->dispatchEvent('itemExists', new \BearFramework\App\Cache\ItemExistsEventDetails($key, $exists));
        }
        if ($this->hasEventListeners('itemRequest')) {
            $this->dispatchEvent('itemRequest', new \BearFramework\App\Cache\ItemRequestEventDetails($key));
        }
        return $exists;
    }
16434
public function keyExists($key)
    {
        $exists = true;
        try {
            $this->get($key);
        } catch (Exception $e) {
            $exists = false;
        }
        return $exists;
    }
385444
public function __isset( $key )
    {
        // Delegate
        return ( array_key_exists( $key, $this->properties ) || isset( $this->storageOptions->$key ) );
    }
659989
protected function exists($key)
    {
        $data = $this->read($key);
        if ($data === false) {
            return false;
        }

        $expire = $data[0];
        if ($expire !== 0 && $expire < time()) {
            // expired, don't keep it around
            $path = $this->path($key);
            $this->filesystem->delete($path);

            return false;
        }

        return true;
    }
907838
protected function checkForRelationsAttributes($key) {
    try {
      $key = $this->$key();
    } catch (\BadMethodCallException $e) {
      return false;
    }

    return is_subclass_of($key, $this->eloquent_relation_class);
  }
266238
public function exists(?string $key = null) : bool
    {
        $key = $this->constructKey($key);

        return $this->parseKey($key, function ($part, $result) {
            return array_key_exists($part, $result);
        });
    }
590745
public function exists($key)
    {
        if ($this->enabled) {
            return !$this->pool->getItem($key)->isMiss();
        } else {
            return false;
        }
    }