.net 6 让swagger支持上传文件

发布时间：2022-03-04 09:48:49来源：网络阅读（891）

API代码 

[HttpPost]
        public ApiResult<string> UpFile(List<IFormFile> files)
        {
           
            if (files.Count != 1) throw new MyException("只允许上传一个文件");
            var basePath = Path.Combine(_hostingEnvironment.WebRootPath);
            var savePath = Path.Combine(basePath, "zlfile");
            var fileName=DateTime.Now.ToFileTime();
            var file=files[0];
            var fileType=Path.GetExtension(file.FileName).ToLower();
            using (var stream = new FileStream(Path.Combine(savePath, $"{fileName}{fileType}"), FileMode.CreateNew))
            {
                file.CopyToAsync(stream).Wait();
            }
            return Response($"/zlfile/{fileName}{fileType}");
        }

然后再看swagger ，度娘下，就是需要增加个 IOperationFilter 来实现，看代码

public class FileUploadOperation : IOperationFilter
{
    public void Apply(Operation operation, OperationFilterContext context)
    {
        if (operation.OperationId.ToLower() == "apivaluesuploadpost")
        {
            operation.Parameters.Clear();
            operation.Parameters.Add(new NonBodyParameter
            {
                Name = "uploadedFile",
                In = "formData",
                Description = "Upload File",
                Required = true,
                Type = "file"
            });
            operation.Consumes.Add("multipart/form-data");
        }
    }
}

然后，在services.ConfigureSwaggerGen()参数中，添加


options.OperationFilter<FileUploadOperation>(); 

方法的原理是通过重写操作某个特定API的的过滤器，来实现对返回内容的操作。


由于.NET 5 自带了swagger都支持的是OpenAPI 3，这个方法不好用了。不过思想应该相同，首先看看OpenAPI 3的规范。

文件上传需要定义为：


requestBody:
  content:
    multipart/form-data:
      schema:
        type: object
        properties:
          fileName:
            type: string
            format: binary

这个套路和OpenAPI 2完全不一样，需要重新设置requestBody才行。


public class FileUploadOperation : IOperationFilter
{
    public void Apply(OpenApiOperation operation, OperationFilterContext context)
    {
        //判断上传文件的类型，只有上传的类型是IFormCollection的才进行重写。
        if (context.ApiDescription.ActionDescriptor.Parameters.Any(w => w.ParameterType == typeof(IFormCollection)))
        {
            Dictionary<string, OpenApiSchema> schema = new Dictionary<string, OpenApiSchema>();
            schema["fileName"] = new OpenApiSchema { Description = "Select file", Type = "string", Format = "binary" };
            Dictionary<string, OpenApiMediaType> content = new Dictionary<string, OpenApiMediaType>();
            content["multipart/form-data"] = new OpenApiMediaType { Schema = new OpenApiSchema { Type = "object", Properties = schema } };
            operation.RequestBody = new OpenApiRequestBody() { Content = content };
        }
    }
}

执行之后，swagger已经可以正常识别了，通过选择文件即可上传，效果如下：



参考资料#

• https://docs.microsoft.com/en-us/aspnet/core/tutorials/getting-started-with-swashbuckle?view=aspnetcore-5.0&tabs=visual-studio
• https://docs.microsoft.com/en-us/aspnet/core/mvc/models/file-uploads?view=aspnetcore-5.0#upload-large-files-with-streaming
• https://www.talkingdotnet.com/how-to-upload-file-via-swagger-in-asp-net-core-web-api/