Webiny\Component\Entity\AbstractEntity::save PHP Method

    public function save()
    {
        $objectHash = spl_object_hash($this);
        if (array_key_exists($objectHash, self::$saved)) {
            return true;
        }
        self::$saved[$objectHash] = true;
        $data = [];
        $validation = [];
        $one2many = AttributeType::ONE2MANY;
        $many2many = AttributeType::MANY2MANY;
        /* @var $attr AbstractAttribute */
        foreach ($this->getAttributes() as $key => $attr) {
            if ($attr->isRequired() && !$attr->hasValue()) {
                $ex = new ValidationException(ValidationException::VALIDATION_FAILED);
                $ex->addError($key, ValidationException::REQUIRED);
                $validation[$key] = $ex;
                continue;
            }
            if (!count($validation) && !$this->isInstanceOf($attr, $one2many) && !$this->isInstanceOf($attr, $many2many)) {
                if ($attr->getStoreToDb()) {
                    $data[$key] = $attr->getDbValue();
                }
            }
        }
        // Throw EntityException with invalid attributes
        if (count($validation)) {
            $attributes = [];
            foreach ($validation as $attr => $error) {
                foreach ($error as $key => $value) {
                    $attributes[$key] = $value;
                }
            }
            $ex = new EntityException(EntityException::VALIDATION_FAILED, [count($validation)]);
            $ex->setInvalidAttributes($attributes);
            throw $ex;
        }
        /**
         * Insert or update
         */
        $mongo = $this->entity()->getDatabase();
        if (!$this->exists()) {
            $data['_id'] = $mongo->isId($data['id']) ? $mongo->id($data['id']) : $mongo->id();
            $data['id'] = (string) $data['_id'];
            $mongo->insertOne(static::$entityCollection, $data);
            $this->id = $data['id'];
        } else {
            $where = ['_id' => $mongo->id($this->id)];
            $mongo->update(static::$entityCollection, $where, ['$set' => $data], ['upsert' => true]);
        }
        /**
         * Now save One2Many values
         */
        foreach ($this->getAttributes() as $attr) {
            /* @var $attr One2ManyAttribute */
            if ($this->isInstanceOf($attr, AttributeType::ONE2MANY) && $attr->isLoaded()) {
                foreach ($attr->getValue() as $item) {
                    $item->getAttribute($attr->getRelatedAttribute())->setValue($this);
                    $item->save();
                }
                /**
                 * The value of one2many attribute must be set to null to trigger data reload on next access.
                 * This is necessary when we have circular references, and parent record does not get it's many2one ID saved
                 * until all child referenced objects are saved. Only then can we get proper links between referenced classes.
                 */
                $attr->setValue(null, true);
            }
        }
        /**
         * Now save Many2Many values
         */
        foreach ($this->getAttributes() as $attr) {
            /* @var $attr Many2ManyAttribute */
            if ($this->isInstanceOf($attr, AttributeType::MANY2MANY)) {
                $attr->save();
            }
        }
        // Now that this entity is saved, remove it from save log
        unset(self::$saved[$objectHash]);
        return true;
    }