Thiết kế website giá rẻ

Question

I receive the error mentioned in the title:

Cannot insert explicit value for identity column in table ‘Products Discussed’ when IDENTITY_INSERT is set to OFF.

I have checked out multiple forum posts, and scoured the internet, and I still cannot fix the issue.

A contact report will be submitted to the database, and a product discussed table will also be updated. The contact report worked perfectly, but the error occurred with the product discussed table.

Please see all the code below:

ContactReportController.cs

[HttpGet]
public async Task<IActionResult> Submit()
{
    var contactReport = new ContactReport
    {
        ProductsDiscussed = new List<ProductDiscussed>
        {
            new ProductDiscussed() // Add one default item
        },
        Report_Date = DateTime.Now
    };

    // Load necessary data for the form
    await LoadFormDataAsync();
    return View(contactReport);
}

[HttpPost]
public async Task<IActionResult> Submit(ContactReport contactReport)
{
    if (User?.Identity?.IsAuthenticated == true)
    {
        if (ModelState.IsValid)
        {
            try
            {
                _logger.LogInformation("Model is valid. Adding contact report to context.");

                // Add the ContactReport to the context
                _context.ContactReports.Add(contactReport);
                await _context.SaveChangesAsync();

                // Ensure EF Core recognizes each product as a new entity
                foreach (var product in contactReport.ProductsDiscussed)
                {
                    // Set the foreign key
                    product.ReportID = contactReport.Report_Id;

                    // Mark the product as a new entity
                    _context.ProductsDiscussed.Add(product);
                }

                await _context.SaveChangesAsync();

                return RedirectToAction("Index");
            }
            catch (Exception ex)
            {
                _logger.LogError(ex, "An error occurred while saving the contact report.");
                ModelState.AddModelError("", "An error occurred while saving the report. Please try again.");
            }
        }
        else
        {
            _logger.LogWarning("Model state is invalid.");
            foreach (var error in ModelState.Values.SelectMany(v => v.Errors))
            {
                _logger.LogWarning(error.ErrorMessage);
            }
        }
    }
    else
    {
        _logger.LogWarning("User is not authenticated.");
        return Unauthorized();
    }

    // Reload data if ModelState is invalid
    await LoadFormDataAsync(); // Method to load the data needed for the form
    return View(contactReport);
}

private async Task LoadFormDataAsync()
{
    var staffList = await _context.Staff.OrderBy(s => s.Name).ToListAsync();
    ViewBag.StaffList = new SelectList(staffList, "StaffId", "Name");

    var countries = await _context.Countries.OrderBy(c => c.CountryName).ToListAsync();
    ViewBag.Countries = new SelectList(countries, "CountryCode", "CountryName");

    var productCategories = await _context.ProductCategories.OrderBy(c => c.CategoryName).ToListAsync();
    ViewBag.ProductCategories = new SelectList(productCategories, "CategoryID", "CategoryName");

    var customers = await _context.Customers.ToListAsync();
    var customerList = customers
        .Select(c => new
        {
            c.CustomerId,
            DisplayName = string.IsNullOrEmpty(c.City)
                ? $"{c.Name} {c.Surname} - {c.Country}"
                : $"{c.Name} {c.Surname} - {c.Country}, {c.City}",
            SortKey = string.IsNullOrEmpty(c.Name) ? c.Surname : $"{c.Name} {c.Surname}"
        })
        .OrderBy(c => c.SortKey)
        .ToList();
    ViewBag.CustomerList = new SelectList(customerList, "CustomerId", "DisplayName");
}

Submit.cshtml

<div id="productsContainer">
    @for (int i = 0; i < Model.ProductsDiscussed.Count; i++)
    {
        <div class="card mb-3">
            <div class="card-body">
                <div class="form-group">
                    <label asp-for="ProductsDiscussed[i].BrandProductCategoriesID">Product Category</label>
                    <select asp-for="ProductsDiscussed[i].BrandProductCategoriesID" class="form-control" asp-items="ViewBag.ProductCategories">
                        <option value="">Select a product category</option>
                    </select>
                    <span asp-validation-for="ProductsDiscussed[i].BrandProductCategoriesID" class="text-danger"></span>
                </div>

                <div class="form-group">
                    <label asp-for="ProductsDiscussed[i].Sample">Sample Used</label>
                    <select asp-for="ProductsDiscussed[i].Sample" class="form-control">
                        <option value="false">No</option>
                        <option value="true">Yes</option>
                    </select>
                    <span asp-validation-for="ProductsDiscussed[i].Sample" class="text-danger"></span>
                </div>
            </div>
        </div>
    }
</div>

<button type="button" id="addProductButton" class="btn btn-secondary mt-3">Add Another Product</button>

Products Discussed ID
IDENTITY(1,1) is used

[Products Discussed ID] [int] IDENTITY(1,1) NOT NULL,

ContactReport.cs

 public ContactReport()
 {
     ProductsDiscussed = new List<ProductDiscussed>();
 }

// Text in-between

[NotMapped]
public List<ProductDiscussed> ProductsDiscussed { get; set; } = new List<ProductDiscussed>();

Product Discussed.cs

[Key]
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
[Column("Products Discussed ID")]
public int ProductsDiscussedID { get; set; } // Manually managed ID

Error received after submitting report

CustomerDatabase.Controllers.ContactReportController: Information: Model is valid. Adding contact report to context.

Microsoft.EntityFrameworkCore.Database.Command: Information: Executed DbCommand [Parameters=[@p0='SUR238' (Nullable = false) (Size = 4000), @p1='test' (Nullable = false) (Size = 4000), @p2='test' (Nullable = false) (Size = 4000), @p3='' (Nullable = false) (Size = 4000), @p4='test' (Nullable = false) (Size = 4000), @p5='2024-08-12T00:00:00.0000000', @p6='test' (Nullable = false) (Size = 4000), @p7='STA11' (Nullable = false) (Size = 4000)], CommandType='Text', CommandTimeout='30']
SET IMPLICIT_TRANSACTIONS OFF;
SET NOCOUNT ON;
INSERT INTO [Contact Report] ([Customer ID], [Feedback], [Follow Up], [Location], [Notes], [Report Date], [Report Description], [Staff Id])
OUTPUT INSERTED.[Id]
VALUES (@p0, @p1, @p2, @p3, @p4, @p5, @p6, @p7);

Microsoft.EntityFrameworkCore.Database.Command: Information: Executed DbCommand [Parameters=[@p8='3', @p9='195', @p10='False'], CommandType='Text', CommandTimeout='30']
SET IMPLICIT_TRANSACTIONS OFF;
SET NOCOUNT ON;
INSERT INTO [Products Discussed] ([Brand Product Categories], [Report ID], [Sample])
OUTPUT INSERTED.[Products Discussed ID]
VALUES (@p8, @p9, @p10);

Exception thrown: 'Microsoft.Data.SqlClient.SqlException' in Microsoft.Data.SqlClient.dll
Microsoft.EntityFrameworkCore.Database.Command: Error: Failed executing DbCommand [Parameters=[@p0='18', @p1='3', @p2='195', @p3='False'], CommandType='Text', CommandTimeout='30']
SET IMPLICIT_TRANSACTIONS OFF;
SET NOCOUNT ON;
INSERT INTO [Products Discussed] ([Products Discussed ID], [Brand Product Categories], [Report ID], [Sample])
VALUES (@p0, @p1, @p2, @p3);

Microsoft.EntityFrameworkCore.DbUpdateException: An error occurred while saving the entity changes. See the inner exception for details.
 ---> Microsoft.Data.SqlClient.SqlException (0x80131904): Cannot insert explicit value for identity column in table 'Products Discussed' when IDENTITY_INSERT is set to OFF.

Danh mục