绑定属性为空

时间:2019-01-17 12:43:02

标签: c# asp.net-core asp.net-core-mvc

我是新来的,试图弄清楚发生了什么,并认为这是最好的询问场所。好吧,当我选择项目并按下添加按钮时,属性[Bind“”] Model变为null,但是为什么呢?

这是我的观点:

@model PortfolioDetailsVM
<form asp-controller="Portfolio" asp-action="AddProject" method="POST">
    <div class="form-group">
        <div class="input-group mb-3">
            <select asp-for="PortfolioProjects.ProjectId" class="custom-select form-control">
                <option disabled selected value="@null">Choose...</option>
                @foreach (var item in Model.Projects)
                {
                    <option value="@item.ProjectID">@item.Title</option>
                }
            </select>

var PortfolioVM的所有数据都为空。 这是我的控制器和我的视图模型:

namespace PEG.Models
{
    public class PortfolioDetailsVM
    {
        public PortfolioDetailsVM()
        {
            Portfolios = new Portfolio();
            PortfolioProjects = new PortfolioProject();
        }
        public Portfolio Portfolio;
        public PortfolioProject PortfolioProjects;
        public IEnumerable<Project> Projects;
    }
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> AddProject([Bind("PortfolioProject")]PortfolioDetailsVM PortfolioVM) //<----Null
{
    var addproject = PortfolioVM.PortfolioProjects;

    if (ModelState.IsValid)
    {
        try
        {
            context.Update(addproject);
            await context.SaveChangesAsync();
            return RedirectToAction("Details", "Portfolio" + PortfolioVM.PortfolioProjects.PortfolioId);
        }
        catch (DbUpdateException)
        {
            ModelState.AddModelError("", "Unable to save changes. " +
            "Try again, and if the problem persists, " +
            "see your system administrator.");
        }

    }

    return RedirectToAction("Index", "Portfolio");
}

这是另一个模型和详细信息方法:

 // GET: Portfolio/Details/5
    public async Task<ActionResult> Details(int id)
    {
        PortfolioDetailsVM PortfolioVM = new PortfolioDetailsVM
        {
            Projects = await context.Project.Include(x => x.Task).ToListAsync(),
            Portfolios = await context.Portfolio.SingleOrDefaultAsync(x => x.PortfolioID == id)
        };

        return View(PortfolioVM);
    }
namespace PEG.Models
{
    public partial class PortfolioProject
    {
        [DatabaseGenerated(DatabaseGeneratedOption.Computed)]
        [Column(TypeName = "datetime2")]
        public DateTime? CreatedDate { get; set; }

        //RelationsId
        [Key]
        [Column(Order = 0)]
        public int PortfolioId { get; set; }

        [Key]
        [Column(Order = 1)]
        public string ProjectId { get; set; }

        //Relations
        [ForeignKey("PortfolioId")]
        public virtual Portfolio Portfolio { get; set; }

        [ForeignKey("ProjectId")]
        public virtual Project Project { get; set; }
    }
}

1 个答案:

答案 0 :(得分:1)

绑定到属性

首先,您已经在ViewModels中定义了字段。可以在您的视图中读取它们,但是要使模型绑定起作用,您需要使用get和set访问器将它们声明为属性

public class PortfolioDetailsVM
{
    //...

    public Portfolio Portfolio { get; set; }
    public PortfolioProject PortfolioProject { get; set; }
    public IEnumerable<Project> Projects { get; set; }
}

这应该使您的绑定代码有效。

更好的绑定模型

第二,您使用模型绑定的方式略有不正确。尽量不要直接绑定到数据模型(例如PortfolioProject的类型)。您要绑定的模型不应包含对数据模型类型的任何引用。

相反,我通常只声明我要绑定到的模型中真正需要的内容,这样我就不必再使用ol'Bind属性。您的情况的一个简单示例:

public class DetailsAddProjectVM
{
    public string SelectedProjectId { get; set; }
}

以相应的形式:

@model PortfolioDetailsVM
<select asp-for="SelectedProjectId" class="custom-select form-control">
   ...
</select>

哪个发布到

public async Task<IActionResult> AddProject(DetailsAddProjectVM bindingModel)
{
   //look ma, no [Bind]!
   var projectid = bindingModel.SelectedProjectId;
}

当然,要渲染相应的表单,还必须在原始SelectedProjectId中声明一个PortfolioDetailsVM属性。

如您所见,您根本没有绑定