Get the mapping attribute by special metakey.

@param  string $metakey The metakey key to get attribute.
@return string|null
189555
public function get_mapping_attribute( $metakey ) {
		$mapping = array_flip( $this->get_mapping() );

		return isset( $mapping[ $metakey ] ) ? $mapping[ $metakey ] : null;
	}
239667
public function getMetadata($key = null)
	{
		if (! \is_resource($this->resource))
		{
			return null;
		}

		$metadata = \stream_get_meta_data($this->resource);

		if (! (null === $key))
		{
			return $metadata[$key] ?? null;
		}

		return $metadata;
	}
103230
public function &get($key)
	{
		$out = ($this->exists($key)) ? $this->meta[$key] : false;
		return $out;
	}
501364
public function getMetadata($key = null)
    {
        if (!$key) {
            return $this['metadata'];
        }

        if (isset($this->definition['metadata'][$key])) {
            return $this->definition['metadata'][$key];
        }

        return null;
    }
623568
public function getAttribute(string $key)
    {
        $attribute = $this->tag->getAttribute($key);
        if ( ! is_null($attribute)) {
            $attribute = $attribute['value'];
        }

        return $attribute;
    }
511552
public function meta($metaKey = '', $single = true)
	{
		$meta_values = get_post_meta($this->ID, $metaKey, $single);

		return $meta_values;
	}
1153840
function meta( $key )
    {
        $content = array();
        if ( file_exists( $this->MetaFileName ) )
        {
            $content = unserialize( file_get_contents( $this->MetaFileName ) );
        }
        return isset( $content[$key] ) ? $content[$key] : null;
    }
45284
public function getAttributeFromMeta($key)
    {
        if (! $key) {
            return;
        }

        // Here we will determine if the model base class itself contains this given key
        // since we do not want to treat any of those methods are relationships since
        // they are all intended as helper methods and none of these are relations.
        if (method_exists(self::class, $key)) {
            return;
        }

        $meta = json_decode($this->getAttribute('meta'));
        if (isset($meta->$key)) {
            return $meta->$key;
        }

        $user = $meta->user;
        if (isset($user->$key)) {
            return $user->$key;
        }
    }
638754
public function getAttribute($attributeKey)
    {
        $hasReservedPrefix = strpos($attributeKey, self::RESERVED_ATTRIBUTE_PREFIX) === 0;

        if (isset($this->_attributeKeyMap[$attributeKey])) {
            if ($hasReservedPrefix) {
                $this->_logger->log(
                    Logger::WARNING,
                    sprintf('Attribute %s unexpectedly has reserved prefix %s; using attribute ID instead of reserved attribute name.', $attributeKey, self::RESERVED_ATTRIBUTE_PREFIX)
                );
            }

            return $this->_attributeKeyMap[$attributeKey];
        }

        if ($hasReservedPrefix) {
            return new Attribute($attributeKey, $attributeKey);
        }

        $this->_logger->log(Logger::ERROR, sprintf('Attribute key "%s" is not in datafile.', $attributeKey));
        $this->_errorHandler->handleError(new InvalidAttributeException('Provided attribute is not in datafile.'));
        
        return null;
    }
36278
function getMetaData($key = null)
    {
        $data = $this->data;
        if ($key !== null)
            $data = ( isset($data[$key]) ) ? $data[$key] : null;


        return $data;
    }
1228055
public function getAttribute($key = null)
    {
        if ($this->attributes === null) {
            $this->parseAttributes();
        }

        if (is_null($key)) {
            return $this->attributes;
        }

        if (!array_key_exists($key, $this->attributes)) {
            return null;
        }

        return $this->attributes[$key];
    }
1027251
public function getAttribute($key)
    {
        $key = $this->reFormatForCompatibility($key);

        return (property_exists($this, $key)) ? $this->{$key} : null;
    }
919289
public function getMetadata($key = null)
    {
        $meta = stream_get_meta_data($this->buffer);

        if (!isset($key)) {
            return $meta;
        }

        if (isset($meta[$key])) {
            return $meta[$key];
        }
    }
268454
public function getAttribute($key)
    {

        // query whether the identifier exists or not
        if (isset($this[$uid = $this->maskKey($key)])) {
            return $this[$uid];
        }
    }
1332085
private function getKey ( $key = NULL ) {
        if ($key === NULL) {
            $key = $this->__keyName;
            return $this->getClassKey() . '_' . $this->$key;
        }
        return $this->getClassKey() . '_' . $key;
    }
832468
public function getValue($key, $default = null)
    {
        $meta = $this->meta;

        if (isset($meta[$key])) {
            return $meta[$key];
        }

        return $default;
    }
63764
public function get($key)
    {
        if (!isset($this->attributes[$key])) {
            return false;
        }

        return $this->attributes[$key];
    }