Adding more than one object to another - asp.net-core

Question

I've been working on my version of the app made in this tutorial (https://learn.microsoft.com/pl-pl/aspnet/core/data/ef-rp/complex-data-model?view=aspnetcore-5.0&tabs=visual-studio). And I've got question about a connection between two objects. My idea is to add more than one Material to Paczka. I've manage to connect them together but I can add only one Material. So my question is what should I do to be able to connect more than one?
Object Material
public class Material
{
[Key]
public int PaczkaID { get; set; }
public string Name { get; set; }
public string PN { get; set; }
public string Cert { get; set; }
public string Qty { get; set; }
public Paczka Paczka { get; set; }
}
And object Paczka
public class Paczka
{
public int PaczkaID { get; set; }
public string CRS { get; set; }
public string WO { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public Material Material { get; set; }
}
Here is how I can add Material to Paczka
public class MaterialModel : PageModel
{
private readonly Pasto.Data.PastoContext _context;
public MaterialModel(Pasto.Data.PastoContext context)
{
_context = context;
}
[BindProperty]
public Paczka Paczka { get; set; }
public async Task<IActionResult> OnGetAsync(int? id)
{
if (id == null)
{
return NotFound();
}
Paczka = await _context.Paczkas
.Include(i => i.Material)
.AsNoTracking()
.FirstOrDefaultAsync(m => m.PaczkaID == id);
if (Paczka == null)
{
return NotFound();
}
return Page();
}
public async Task<IActionResult> OnPostAsync(int? id)
{
if (id == null)
{
return NotFound();
}
var paczkaToUpdate = await _context.Paczkas
.Include(i => i.Material)
.FirstOrDefaultAsync(s => s.PaczkaID == id);
if (paczkaToUpdate == null)
{
return NotFound();
}
if (await TryUpdateModelAsync<Paczka>(
paczkaToUpdate,
"Paczka",
i => i.Material))
{
if (String.IsNullOrWhiteSpace(
paczkaToUpdate.Material?.Name))
{
paczkaToUpdate.Material = null;
}
await _context.SaveChangesAsync();
return RedirectToPage("./Index");
}
return Page();
}
}
And HTML
a<form method="post">
<table class="table">
<thead>
<tr>
<th>
<strong>Name</strong>
</th>
<th>
<strong>P/N</strong>
</th>
<th>
<strong>Certificate</strong>
</th>
<th>
<strong>Quantity</strong>
</th>
</tr>
</thead>
<div class="form-group">
<tbody>
<tr>
<td>
<input asp-for="Paczka.Material.Name" class="form-control" />
</td>
<td>
<input asp-for="Paczka.Material.PN" class="form-control" />
</td>
<td>
<input asp-for="Paczka.Material.Cert" class="form-control" />
</td>
<td>
<input asp-for="Paczka.Material.Qty" class="form-control" />
</td>
</tr>
</tbody>
</div>
</table>
<div class="form-group">
<input type="submit" value="Save" class="btn btn-primary" />
<a asp-page="./Index" class="btn btn-danger">Back to List</a>
</div>

Answer 1

I want Paczka to have many Materials. The material should belong only
to one Paczka because I want to create them while creating Paczka
From your description, the Paczka and Materials should be configured one-to-many relationship. In the Paczka class, use List or ICollection to define the navigation property (Material), code like this:
public class Paczka
{
public int PaczkaID { get; set; }
public string CRS { get; set; }
public string WO { get; set; }
public DateTime StartDate { get; set; }
public DateTime EndDate { get; set; }
public List<Material> Material { get; set; }
}
public class Material
{
[Key]
public int PaczkaID { get; set; }
public string Name { get; set; }
public string PN { get; set; }
public string Cert { get; set; }
public string Qty { get; set; }
//the foreign key
public int PaczkaForeignKey { get; set; }
[ForeignKey("PaczkaForeignKey")]
public Paczka Paczka { get; set; }
}
Then, in the View page, you could use #for statement to loop through the Material and display the related data, code like this:
#page
#model RazorPageSample.Pages.MaterialModel
#{
}
<div class="row">
<div class="col-md-4">
<form method="post">
<div asp-validation-summary="ModelOnly" class="text-danger"></div>
<input type="hidden" asp-for="Paczka.PaczkaID" />
<div class="form-group">
<label asp-for="Paczka.CRS" class="control-label"></label>
<input asp-for="Paczka.CRS" class="form-control" />
<span asp-validation-for="Paczka.CRS" class="text-danger"></span>
</div>
#for (var i = 0; i < Model.Paczka.Material.Count; i++)
{
<div class="form-group">
<label asp-for="Paczka.Material[i].PaczkaID" class="control-label"></label>
<input asp-for="Paczka.Material[i].PaczkaID" class="form-control" />
<span asp-validation-for="Paczka.Material[i].PaczkaID" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Paczka.Material[i].Name" class="control-label"></label>
<input asp-for="Paczka.Material[i].Name" class="form-control" />
<span asp-validation-for="Paczka.Material[i].Name" class="text-danger"></span>
</div>
<div class="form-group">
<label asp-for="Paczka.Material[i].Cert" class="control-label"></label>
<input asp-for="Paczka.Material[i].Cert" class="form-control" />
<span asp-validation-for="Paczka.Material[i].Cert" class="text-danger"></span>
</div>
}
<div class="form-group">
<input type="submit" value="Save" class="btn btn-primary" />
</div>
</form>
</div>
</div>
Then, in the Post method, get the update value and insert or update the data to database, screenshot like this:
More detail information about relationships and update related entity, refer the following articles:
Relationships
Configuring One To Many Relationships in Entity Framework Core
Update related data - ASP.NET MVC with EF Core