According to article 545 of the Civil Code
A creditor who transfers his creditor's rights may transfer all or part of his creditor's rights to a third party, except in any of the following circumstances:
(a) according to the nature of the creditor's rights shall not be transferred;
(two) according to the agreement of the parties shall not be transferred;
(3) It shall not be transferred according to law.
If the parties agree that the non-monetary creditor's rights cannot be transferred, they may not confront a bona fide third party. If the parties agree that the creditor's rights are not transferable, they may not oppose a third party.
legal ground
Article 546th of the Civil Code of People's Republic of China (PRC) * * * Creditor's right is notified to transfer the creditor's right. If the debtor is not notified, the assignment is invalid to the debtor. The notice of assignment of creditor's rights shall not be revoked, except with the consent of the transferee.