接收多部分表单数据json参数为空

Question

我正在尝试从postman接收包含3个参数的多部分请求：

• 一个int
• 文件
• 一个JSON

我在控制器中接收到文件和整数fine，但json的所有字段都为NULL。会有什么问题吗？

JSON

    [Serializable]
    public class ProcessingRecipe
    {
        [JsonPropertyName("fileId")]
        public string FileID { get; set; }
        [JsonPropertyName("srcLang")]
        public string SrcLang { get; set; }

    }

控制器

    [HttpPost]
    [Route(Routes.Routes.File.PROCESS)]
    public async Task<ActionResult<FileProcessResponse>> ProcessFileAsync([FromForm]IFormFile uploadFile,[FromForm] ProcessingRecipe recipe,[FromForm]int aa)
    {
             //the file is ok
            // the int is 33
    }

邮差

public class JsonModelBinder : IModelBinder {
    public Task BindModelAsync(ModelBindingContext bindingContext) {
        if (bindingContext == null) {
            throw new ArgumentNullException(nameof(bindingContext));
        }

        // Check the value sent in
        var valueProviderResult = bindingContext.ValueProvider.GetValue(bindingContext.ModelName);
        if (valueProviderResult != ValueProviderResult.None) {
            bindingContext.ModelState.SetModelValue(bindingContext.ModelName, valueProviderResult);

            // Attempt to convert the input value
            var valueAsString = valueProviderResult.FirstValue;
            var result = Newtonsoft.Json.JsonConvert.DeserializeObject(valueAsString, bindingContext.ModelType);
            if (result != null) {
                bindingContext.Result = ModelBindingResult.Success(result);
                return Task.CompletedTask;
            }
        }

        return Task.CompletedTask;
    }
}

public async Task<ActionResult<FileProcessResponse>> ProcessFileAsync([FromForm]IFormFile uploadFile,[ModelBinder(typeof(JsonModelBinder))] ProcessingRecipe recipe)
        {
                 //the file is ok
                // the int is 33
        }

Answer 1

这与如何在postman中上传文件和json数据完全相同

在您的情况下，也许您可以尝试下面(https://stackoverflow.com/A/52748531/11226302)中建议的内容