从字节返回FileResult [] [英] Return a FileResult from a byte[]

问题描述

我正在研究ASP.NET Core API.该API是数据库驱动的.

I am working on an ASP.NET Core API. The API is database driven.

我正在将图像存储在数据库中，我的 ArtistImage.cs 实体如下所示:

I am storing images in the database, my ArtistImage.cs entity looks like this:

ArtistImage.cs

public class ArtistImage
{
    public int Id { get; set; }

    public byte[] Data { get; set; }

    public DateTime CreatedAt { get; set; }

    public DateTime? ModifiedAt { get; set; }

    public int ArtistId { get; set; }

    public Artist Artist { get; set; }
}

如何将 byte [] 转换为类似的内容: return File(〜/Images/photo.jpg"，"image/jpeg"); 其中只会为图片服务?

How can I convert a byte[] to something like: return File("~/Images/photo.jpg", "image/jpeg"); where that would simply serve the image?

我要避免先将字节数组写入本地系统文件.

I want avoid writing the byte array to a local system file first.

我尝试过的事情

我尝试了下面的方法，但是显然，我不能像这样使用 File .

I have tried the method below, but apparently, I can't use File like that.

public class ImagesService : IImagesService 
{
    private readonly DbContext context;

    public ImagesService(DbContext context)
    {
        this.context = context;
    }

    public async Task<FileResult> GetArtistImageAsync(int imageId)
    {
      byte[] imageBytes = await context
        .ArtistImages
        .Where(ai => ai.Id == imageId)
        .Select(ai => ai.Data)
        .SingleOrDefaultAsync();

      return System.IO.File(imageBytes, "image/jpg", "test");
    }
}

推荐答案

这似乎是

This appears to be an XY problem. You are mixing up controller helper methods and trying to access them from an unrelated service.

我建议您重构服务以返回字节数组

I would suggest you refactor the service to return the byte array

ImagesService

public Task<byte[]> GetArtistImageAsync(int imageId) {
    return context.ArtistImages
            .Where(ai => ai.Id == imageId)
            .Select(ai => ai.Data)
            .SingleOrDefaultAsync();
}

然后让控制器返回FileResult

and then have the controller return the FileResult

控制器

public async Task<IActionResult> SomeAction(....) {
    //...

    var bytes = await imagesService.GetArtistImageAsync(imageId);
    return File(bytes,  "image/jpeg");
}

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