I create class Project in project class I define technology and another i define Class Technology I seed data in technology and after that i create dropdown list in Project Create view using a partial view and when I save data the technology can not be saved

public class Project
{
    public int ProjectId { get; set; }

    [StringLength(60, MinimumLength = 3)]
    public string? ProjectName { get; set; }

    public string? Description { get; set; }

    public DateTime Start { get; set; }
    public DateTime? End { get; set; }

    public string? ProjectHead { get; set; }
    public string? Status { get; set; }
    public string? Technology { get; set; }
}

public class Technology
{
    public int TechnologyId { get; set; }
    public string? TechnologyName { get; set; }
}

This is my controller:

public async Task<IActionResult> Create([Bind("ProjectId,ProjectName,Description,Start,End,ProjectHead,Status,Technology")] Project project)
{
        if (ModelState.IsValid)
        {
            _context.Add(project);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

        return View(project);
}

This is my view of project create:

<div >
        <partial name="_Technologypartial" />
</div>

technology Patial

@model TeamManagement.Models.Technology

<div >
    <div >
        <label>Technology</label>
        <br />
        <select asp-for="TechnologyId"  asp-items="@(new SelectList(ViewBag.Technology,"TechnologyId","TechnologyName"))">
        </select>
    </div>
</div>

---

EDIT

View

<div >
        <partial name="_Technologypartial" model="@Model.technology" />
    </div>

Controller

 {
            var list = _context.Technology.ToList();

            List<SelectListItem> dropdown = new List<SelectListItem>();
            foreach (var item in list)
            {
                dropdown.Add(new SelectListItem()
                {
                    Text = item.TechnologyName,
                    Value = item.TechnologyId.ToString()
                });
            }

            PartialViewData model = new PartialViewData();
            ViewBag.Technology = dropdown;
            return View(model);
        }

[HttpPost]
        [ValidateAntiForgeryToken]
        public async Task<IActionResult> Create(PartialViewData model)
        {
            if (ModelState.IsValid)
            {
                Project project = new Project()
                {
                    ProjectId = model.project.ProjectId,
                    ProjectName = model.project.ProjectName,
                    Description = model.project.Description,
                    Start = model.project.Start,
                    End = model.project.End,
                    ProjectHead = model.project.ProjectHead,
                    Status = model.project.Status,
                    Technology = model.technology.TechnologyId.ToString()
                };
                _context.Add(project);
                await _context.SaveChangesAsync();
                return RedirectToAction(nameof(Index));
            }

            return View(model);

        }

CodePudding user response：

When you select an option in Partial View, After submiting the form, You want save the value of option. I suggest you to use ViewModel to achieve it. Refer to this simple demo:

I simplified your class for testing convenience.

public class Project
    {
        public string Name { get; set; }
        public string? Technology { get; set; }
    }

public class Technology
    {
        public int TechnologyId { get; set; }
        public string? TechnologyName { get; set; }
    }

Create a View model to pass the value.

public class PartialViewData
    {
        public PartialViewData()
        {
            project = new Project();
            technology = new Technology();  
        }
        public Project project { get; set; }
        public Technology technology { get; set; } 
    }

DbContext

 public class MvcMovieContext : DbContext
    {
        public MvcMovieContext(DbContextOptions<MvcMovieContext> options) : base(options)
        {

        }
        public DbSet<Technology> technology { get; set; }
    }

Controller

 public class HomeController : Controller
    {
        
        private readonly MvcMovieContext _context;

        public HomeController(MvcMovieContext context)
        {
           
            _context = context;
        }

        public IActionResult Index()
        {
            return View();
        }
public IActionResult Privacy()
        {
            var list =  _context.technology.ToList();
             
            List<SelectListItem> dropdown = new List<SelectListItem>();
            foreach(var item in list)
            {
                dropdown.Add(new SelectListItem()
                {
                   Text = item.TechnologyName,
                   Value = item.TechnologyId.ToString()
                }) ;
            }

            PartialViewData model = new PartialViewData();
            ViewBag.Technology = dropdown;
            return View(model);
        }



[HttpPost]
public IActionResult Privacy(PartialViewData model)
{
     Project project = new Project()
          {
              Name = model.project.Name,
              Technology = model.technology.TechnologyId.ToString()
          };
    
                //......
    
     return View();
}
}

View

@model PartialViewData

<form method="post">
    <input asp-for="@Model.project.Name" />

    <div >
        <partial name="_Technologypartial" model="@Model.technology" />
    </div>
    <button type="submit">submit</button>
</form>

_Technologypartial

@model Technology

<div >
    <div >
        <label>Technology</label>
        <br />
        <select name="technology.TechnologyId"  [email protected]>
        </select>
    </div>
</div>

Demo:

Edit=================

public IActionResult Create()
{
     var list =  _context.technology.ToList();

        List<SelectListItem> dropdown = new List<SelectListItem>();
        foreach(var item in list)
        {
            dropdown.Add(new SelectListItem()
            {
               Text = item.TechnologyName,
               Value = item.TechnologyId.ToString()
            }) ;
        }

        PartialViewData model = new PartialViewData();
        ViewBag.Technology = dropdown;
        return View(model);
}
    

    
    [HttpPost]
    [ValidateAntiForgeryToken]
    public async Task<IActionResult> Create(PartialViewData model)
    {
        if (ModelState.IsValid)
        {
            //change here
            var name = _context.Technology.Where(x => x.TechnologyId == model.technology.TechnologyId).Select(x => x.TechnologyName).FirstOrDefault();
            Project project = new Project()
            {
                ProjectId = model.project.ProjectId,
                ProjectName = model.project.ProjectName,
                Description = model.project.Description,
                Start = model.project.Start,
                End = model.project.End,
                ProjectHead = model.project.ProjectHead,
                Status = model.project.Status,

                //change here
                Technology = name
            };
            _context.Add(project);
            await _context.SaveChangesAsync();
            return RedirectToAction(nameof(Index));
        }

         return View(model);
        
    }

View

@model PartialViewData



    <div >
        <partial name="_Technologypartial" model="@Model.technology" />
    </div>

_Technologypartial

@model Technology

<div >
    <div >
        <label>Technology</label>
        <br />
        <select name="technology.TechnologyId"  [email protected]>
        </select>
    </div>
</div>