使用ASP.NET MVC中的Entity Framework将多张图片上传到SQL服务器数据库

Question

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I have been trying to upload multiple pictures to a SQL Server database by using Entity Framework.

I have successfully uploaded one picture to the database before but I need to upload multiple pictures one time.

I tried to take the pictures as ICollection<IFormFile> Pic in the DtoModel and convert them to byte[] in the primary model to store them in the database but it didn't work and I just stored one picture in the database from many I have uploaded.

primary model:

public class property
{
    [Key]
    public int Id { get; set; }
   
    public string Name { get; set; }

    [Required(ErrorMessage = "Photo is required.")]
    public byte[] Pic { get; set; }

    public string PicFromat { get; set; }
}

DtoModel:

public class dtoprop
{
    public string Name { get; set; }

    public ICollection<IFormFile> Pic { get; set; }

    public string PicFromat { get; set; }

}

Controller:

private readonly ApplicationDbContext _context;
private new List<string> _allowedExtenstions = new List<string> { ".jpg", ".png" }; 
private long _maxAllowedPosterSize = 1048576;

public propertiesController(ApplicationDbContext context)
{
    _context = context;
}

[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create( dtoprop model)
{
        if (!ModelState.IsValid)
        {
            return View( model);
        }

        if(!_allowedExtenstions.Contains(Path.GetExtension(model.Pics.FileName.ToLower())))
        {
            ModelState.AddModelError("Pic", "Only .PNG, .JPG images are allowed!");
    
            return View(model);
        }
    
        if (model.Pics.Length > _maxAllowedPosterSize)
        {
            ModelState.AddModelError("Pic", "Poster cannot be more than 1 MB!");
            return View(model);
        }

        using var dataStream = new MemoryStream();

        await model.Pics.CopyToAsync(dataStream);

   using var dataStream = new MemoryStream();
            byte[] conv = null;


            if (model.Pic != null )
            {
                // Loop thru each selected file
                foreach (IFormFile photo in model.Pic)
                {
                    await photo.CopyToAsync(dataStream);

                     conv = dataStream.ToArray();

                }
            }


        var pic = new property
        {
            Name = model.Name,
             Pic = conv,
            PicFromat = model.PicFromat
        };

        _context.Properties.Add(pic);
        _context.SaveChanges();

        return RedirectToAction("Index");
}

So, do I need to create a new image model with a one-to-many relationship with the primary model? or there is a better way can implement this approach without store the images in the wwwroot folder?

Answer 1

rewrite your controller code block as follows:

if (model.Pic != null )
{
    // Loop thru each selected file
    foreach (IFormFile photo in model.Pic)
    {
        var dataStream = new MemoryStream();
        await photo.CopyToAsync(dataStream);

        byte[] conv = dataStream.ToArray();

        var pic = new property()
        {
            Name = model.Name,
            Pic = conv,
            PicFromat = model.PicFromat
        };

        _context.Properties.Add(pic);
    }
}

_context.SaveChanges();

Answer 2

Here are few things you need to consider for such approach ie

Make sure that the underlying database eg in case of SQL server must have data type as VARBINARY(MAX) . this will store the byte array data in a single row.

Seeing your code I can tell that you actually needs multi-row List<byte[]> data type to store the multiple images bytes inside a single row of table.

Since you are just using the datatype byte[] it means that in your foreach loop the last image you convert to byte array will be stored in your variable, meaning in your conv variable you are storing the bytes of single image not multiple images.

Know that any database infrastructure does not allows to store list of anything even byte array in a single row, you eventually need to use one to may database relation to store the list of multiple files byte array in a multiple rows separately .

You may have found some hack, but it eventually runs to data type max limits as either your number of images increases or your image size increases.

In short, you need one to many relation mapping model to store multiple images even in bytes in the database, you can not store multiple images byte array in a single row by design. I hope I am able to clarify few things here.

Answer 3

It sounds like you would need to create a separate table for the Image Name "test1" and the unique ID (primary key) which will be used to locate the collection of images uploaded to separate table.

Upload would require two writes, one to the table that stores the "ImageName" and unique key and second write to upload the images individually with a column linking them back to the "ImageName".