如何在 Razor 页面 asp.net core 上更改上传的图像

Question

我尝试了一种来自 StackOverflow 的文件上传方法，并使用 IHostEnvironment 设置成功上传了图像。但我无法弄清楚Editmodel。我想删除现有照片并在编辑表单中添加一张新照片。

这是模型：

[Key]
    public int PostID { get; set; }
[Required]
    [StringLength(160)]
    public string Title { get; set; }

    public string FeatureImage { get; set; }

这里是 Create.cshtml.cs：

public class CreateModel : PageModel
{
    private readonly RazorApp.Data.ApplicationDbContext _context;
    private readonly IHostEnvironment hostingEnvironment;
    public CreateModel(RazorApp.Data.ApplicationDbContext context, IHostEnvironment environment)
    {
        this.hostingEnvironment = environment;
        _context = context;
    }
    [BindProperty]
    public Post Post { get; set; }

    [BindProperty]
    public IFormFile Image { get; set; }

    
    public async Task<IActionResult> OnPostAsync()
    {
        if (this.Image != null)
        {
            var fileName = GetUniqueName(this.Image.FileName);
            var uploads = Path.Combine(hostingEnvironment.ContentRootPath, "wwwroot/uploads");
            var filePath = Path.Combine(uploads, fileName);
            this.Image.CopyTo(new FileStream(filePath, FileMode.Create));
            this.Post.FeatureImage = fileName; // Set the file name
        }
        var emptyPost = new Post();
        if (await TryUpdateModelAsync<Post>(
            emptyPost,
            "post",
            p => p.Title, p => p.FeatureImage))
        {
            _context.Post.Add(Post);
            await _context.SaveChangesAsync();
            return RedirectToPage("./Index");
        }

        return Page();
    }
    private string GetUniqueName(string fileName)
    {
        fileName = Path.GetFileName(fileName);
        return Path.GetFileNameWithoutExtension(fileName)
               + "_" + Guid.NewGuid().ToString().Substring(0, 4)
               + Path.GetExtension(fileName);
    }
}

正如我所说，上传图片工作正常。但我无法弄清楚edit.cshtml.cs。如何删除现有照片并添加新图像？

Answer 1

这是一个工作示例，您可以参考：

编辑.cshtml

<div class="col-md-4">
    <form method="post" enctype="multipart/form-data">
        <div asp-validation-summary="ModelOnly" class="text-danger"></div>
        <input type="hidden" asp-for="Post.PostID" />
        <div class="form-group">
            <label asp-for="Post.Title" class="control-label"></label>
            <input asp-for="Post.Title" class="form-control" />
            <span asp-validation-for="Post.Title" class="text-danger"></span>
        </div>
        <div class="form-group">
            <label asp-for="Post.FeatureImage" class="control-label"></label>
            <input asp-for="Post.FeatureImage" class="form-control" />
            <span asp-validation-for="Post.FeatureImage" class="text-danger"></span>
        </div>
        <div class="form-group">
            <label  class="control-label">New Image</label>
            <input asp-for="Image" class="form-control" />
        </div>
        <div class="form-group">
            <input type="submit" value="Save" class="btn btn-primary" />
        </div>
    </form>
</div>

编辑.cshtml.cs

 public class EditModel : PageModel
{
    private readonly ChangeUploadedImage.Data.MyDbContext _context;
    private readonly IHostingEnvironment hostingEnvironment;

    public EditModel(MyDbContext context, IHostingEnvironment environment)
    {
        _context = context;
        hostingEnvironment = environment;
    }

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

    [BindProperty]
    public IFormFile Image { get; set; }

    public async Task<IActionResult> OnPostAsync()
    {
        if (!ModelState.IsValid)
        {
            return Page();
        }

        if (this.Image != null)
        {
            var path = Path.Combine(hostingEnvironment.ContentRootPath, "wwwroot/uploads", Post.FeatureImage);

            if (System.IO.File.Exists(path))
            {
                System.IO.File.Delete(path);
            }
            var fileName = GetUniqueName(this.Image.FileName);
            var uploads = Path.Combine(hostingEnvironment.ContentRootPath, "wwwroot/uploads");
            var filePath = Path.Combine(uploads, fileName);
            this.Image.CopyTo(new FileStream(filePath, FileMode.Create));
            this.Post.FeatureImage = fileName;
        }
        _context.Attach(Post).State = EntityState.Modified;

        try
        {
            await _context.SaveChangesAsync();
        }
        catch (DbUpdateConcurrencyException)
        {
            if (!PostExists(Post.PostID))
            {
                return NotFound();
            }
            else
            {
                throw;
            }
        }
        return RedirectToPage("./Index");
    }

    private string GetUniqueName(string fileName)
    {
        fileName = Path.GetFileName(fileName);
        return Path.GetFileNameWithoutExtension(fileName)
               + "_" + Guid.NewGuid().ToString().Substring(0, 4)
               + Path.GetExtension(fileName);
    }
}