Code of Civil Procedure section 474 permits a plaintiff to amend complaints by adding parties as Doe defendants "when the plaintiff is ignorant of the name of a defendant" at the time the complaint is filed. Code of Civil Procedure section 474 provides in pertinent part: "When the plaintiff is ignorant of the name of a defendant, he must state that fact in the complaint, or the affidavit if the action is commenced by affidavit, and such defendant may be designated in any pleading or proceeding by any name, and when his true name is discovered, the pleading or proceeding must be amended accordingly . . . ." "The purpose of section 474 is to enable a plaintiff to avoid the bar of the statute of limitations when he or she is ignorant of the identity of the defendant." (Olden v. Hatchell (1984) 154 Cal. App. 3d 1032, 1037 201 Cal. Rptr. 715.) The cases discussing section 474 deal with whether the plaintiff was truly ignorant of the identity of the person brought into the case as a Doe defendant because if that requirement is met, the amendment to the complaint relates back to the date the complaint was filed and the statute of limitations is preserved. (Parker v. Robert E. McKee, Inc. (1992) 3 Cal. App. 4th 512, 514 4 Cal. Rptr. 2d 347; Balon v. Drost (1993) 20 Cal. App. 4th 483 25 Cal. Rptr. 2d 12; Hazel v. Hewlett, supra, 201 Cal. App. 3d 1458; Munoz v. Purdy (1979) 91 Cal. App. 3d 942 154 Cal. Rptr. 472.) For example, in Woo v. Superior Court (1999) 75 Cal. App. 4th 169, 176 89 Cal. Rptr. 2d 20, the court stated: "If the requirements of section 474 are satisfied, the amended complaint substituting a new defendant for a fictitious Doe defendant filed after the statute of limitations has expired is deemed filed as of the date the original complaint was filed."