如何将对象列表存储到ViewState中
我有一个List类型的List 。 我想将它存储在ViewState中。 怎么做到这一点？
private List JobSeekersList { get; set; }
基本上你只需要使用get ，然后就可以从视图状态获取发布的数据，或者在视图状态下第一次设置它。 这是更强大的代码，可以避免对每个调用进行所有检查（视图状态设置，存在等），并直接保存并使用视图状态对象。
// using this const you avoid bugs in mispelling the correct key. const string cJobSeekerNameConst = "JobSeeker_cnst"; public List JobSeekersList { get { // check if not exist to make new (normally before the post back) // and at the same time check that you did not use the same viewstate for other object if (!(ViewState[cJobSeekerNameConst] is List )) { // need to fix the memory and added to viewstate ViewState[cJobSeekerNameConst] = new List (); } return (List )ViewState[cJobSeekerNameConst]; } }
避免使用的替代方案
// using this const you avoid bugs in mispelling the correct key. const string cJobSeekerNameConst = "JobSeeker_cnst"; public List JobSeekersList { get { // If not on the viewstate then add it if (ViewState[cJobSeekerNameConst] == null) ViewState[cJobSeekerNameConst] = new List (); // this code is not exist on release, but I check to be sure that I did not // overwrite this viewstate with a different object. Debug.Assert(ViewState[cJobSeekerNameConst] is List ); return (List )ViewState[cJobSeekerNameConst]; } }
并且JobSeeker类必须是[Serializable] as
[Serializable] public class JobSeeker { public int ID; ... }
并且您通常将其简单地称为对象，并且永远不会为null。 也会在回发后返回保存的viewstate值
JobSeekersList.add(new JobSeeker(){ID=1}); var myID = JobSeekersList[0].ID;
private IList JobSeekersList { get { // to do not break SRP it's better to move check logic out of the getter return ViewState["key"] as List ; } set { ViewState["key"] = value; } }