了解 Razer 数据持久性

Question

我目前正在学习 razor pages，但遇到了这个问题：

我有一个自定义 class，其中包含一组成员，包括其他自定义数组 classes.
它们在页面启动时启动。之后，用户可以更改值或添加或删除数组行。
但是，一旦用户确认更改，OnPost 就会抛出一个异常，就好像从未启动过数组一样。

解决这个问题的最佳方法是什么？

代码示例：

    [BindProperty(SupportsGet = true)]
    public long UID { get; set; }

    [BindProperty(SupportsGet = true)]
    public int UDEP { get; set; }

    [BindProperty]
    public int nExpenses { get; set; }

    // Custom object
    [BindProperty]
    public Employee Employee { get; set; }

    public void OnGet()
    {
        Employee = new Employee(UID, UDEP);

        // Loading arrays data from a Database
        Employee = Employee.ExtractPersonalData(UID);
        Employee.Expenses.ExtractSheet(Month, Year, Employee.ID);
        Employee.Expenses.ExtractBoard();
        Employee.Expenses.ExtractProjects(Month, Employee.ID);
            // There are 1 boards and 4 projects with 30 decimal[] each

        nExpenses = Employee.Expenses.Boards.Count > 0 ? Employee.Expenses.Boards[0].Projects.Count : 0;
    }


    public IActionResult OnPost()
    {
        // All variables within Employee equal NULL
        if(nExpenses < Employee.Expenses.Boards[0].Projects.Count)
            DeleteRow();
        else if (nExpenses > Employee.Expenses.Boards[0].Projects.Count)
            AddRows();

        Employee.Expenses.SaveSheet();
    }

Answer 1

您应该将 OnGet 方法传递的数据保存在视图中（如 hidden controls），然后将它们传递给 OnPost 方法，而 OnPost 方法需要 receive parameter 从视图中获取 OnGet 方法中的数据.

我创建了一个简单的演示供您参考：

  [BindProperty]
    public Employee Employee { get; set; }

    public void OnGet()
    {
        Employee = new Employee()
        {
            Id = 1,
            Name = "aaaa"
        };
        nExpenses = 1;
    }


    public void OnPost(Employee employee)
    {
    }

查看：

@page
@model WebApplication_core_razorpage.Pages.CodeSampleModel
@*
    For more information on enabling MVC for empty projects, visit http://go.microsoft.com/fwlink/?LinkID=397860
*@
<form method="post">
    @Html.HiddenFor(model => model.Employee.Id)
    @Html.HiddenFor(model => model.Employee.Name)
    <input id="Button1" type="submit" value="button" />
</form>

员工class:

public class Employee
    {
        public int Id { get; set; }
        public string Name { get; set; }
    }

调试过程如下：

了解 Razer 数据持久性

Understanding Razor data persistance

html

c#

asp.net-core

razor-pages