In California public employment is held not by contract, but by statute. ( Miller v. State of California (1977) 18 Cal. 3d 808, 813 [135 Cal. Rptr. 386, 557 P.2d 970].) Relying on Miller, our Supreme Court has made it clear that civil service employees cannot state a cause of action for breach of contract or breach of the implied covenant of good faith and fair dealing. (Shoemaker v. Myers (1990) 52 Cal. 3d 1, 23-24 [276 Cal. Rptr. 303, 801 P.2d 1054, 20 A.L.R.5th 1016].) The covenant of good faith and fair dealing arises out of the contract itself. It is read into contracts to protect the express contractual promises of the contract, rather than to protect a general public policy interest not directly tied to the contract's purposes. (Foley v. Interactive Data Corp. (1988) 47 Cal. 3d 654, 690 [254 Cal. Rptr. 211, 765 P.2d 373] (Foley).) Since the good faith covenant is an implied term of a contract, the existence of a contractual relationship is thus a prerequisite for any action for breach of the covenant. (Smith v. City and County of San Francisco (1990) 225 Cal. App. 3d 38, 49 [275 Cal. Rptr. 17] [appellants could not state cause of action for breach of implied covenant because they were in relationship of real estate developer to government land use regulators, not in contractual relationship].)