c# – 使用angular2将图像上传到asp.net核心

所以我有angular2的asp.net核心应用程序.现在我想上传图片,如果我将其上传为byte [],我就设法这样做了.但后来我无法检查文件是否真的是后端的图像所以我试图寻找另一种解决方案..我发现这个博客关于文件上传： https://devblog.dymel.pl/2016/09/02/upload-file-image-angular2-aspnetcore/但它对我不起作用…

对于文件上传我使用angular2库angular2-image-upload,所以我的图片上传的html部分如下所示：

<image-upload [max]="1" [buttonCaption]="'Browse'" [preview]="false" (change)="onFileChange($event)"></image-upload>
<button (click)="onSaveChanges()" class="btn btn-primary float-left" type="submit">Save</button>

然后我的angular2部分看起来像这样：

onFileChange(event: any) {
    this.file = event.target.files[0];

    if (event.target.files && this.file) {
        var reader = new FileReader();

        reader.onload = (event: any) => {
            this.profilePicture = event.target.result;
        }
        reader.readAsDataURL(this.file);
    }
}

onSaveChanges() {
    this.isSaving = true;
    this.country = this.state.user.country;
    this.userService.userChange(this.firstName,this.lastName,this.country,this.file,this.currentPassword,this.newPassword).subscribe(success => {
        this.state.user.profilePicture = this.profilePicture;
        this.state.user.firstName = this.firstName;
        this.state.user.lastName = this.lastName;
        this.isSaving = false;
        this.passwordError = false;
        this.isSuccessful = true;
        this.currentPassword = '';
        this.newPassword = '';
        this.newPasswordRepeat = '';
    },error => {
        this.isSaving = false;
        this.passwordError = true;
        this.passwordErrorMessage = error._body;
    });
}

我的angular2 api调用看起来像这样：

userChange(firstName: string,lastName: string,country: string,file: File,oldPassword: string,newPassword: string) {
    let input = new FormData();
    input.append("File",file);

    var url = this.baseUrl + "updateUser";

    return this.http.post(url,{ FirstName: firstName,LastName: lastName,Country: country,File: input,OldPassword: oldPassword,NewPassword: newPassword });
}

我的asp.net核心控制器(请注意,我没有显示控制器的主体,因为它是无关紧要的)：

[HttpPost]
public async Task<IActionResult> UpdateUser([FromBody]UserChange userChange)
{ 
}

UserChange类：

public class UserChange
{
    public string FirstName { get; set; }

    public string LastName { get; set; }

    public string Country { get; set; }

    public IFormFile File { get; set; }

    public string OldPassword { get; set; }

    public string NewPassword { get; set; }
}

问题是,当我提交我的图像时,我总是将我的UserChange对象设为null.当我将图像添加为byte []时,它就像魅力一样有什么问题？为什么即使我传递的文件不是null,我也总是为空？我看到的其他事情,当我将类型从IFormFile更改为FormFile时,我的UserChange对象不再为null,但只有来自object的File参数抛出此错误

‘userChange.File.ContentDisposition’ threw an exception of type ‘System.NullReferenceException’

更新1

不知怎的,我设法使用这个答案发送文件到asp.net控制器：File upload using Asp.Net Core Web API file is always null但是这样做我不得不创建另一个没有参数的动作,但是如何在我的情况下发送文件仍然是未知的…

addFile(): void {
    let fi = this.fileInput.nativeElement;
    if (fi.files && fi.files[0]) {
        let fileToUpload = fi.files[0];

        if (fileToUpload) {
            this.uploadService.upload(fileToUpload)
            .subscribe(res => {
                console.log(res);
            });
        }
        else
            console.log("FileToUpload was null or undefined.");
    }
}

upload(fileToUpload: any) {
        let input = new FormData();
        input.append("fileForController",fileToUpload);
        return this.http.post("/api/upload",input );
    }

[HttpPost]
[Route("/api/upload")]
public async Task<IActionResult> Upload(IFormFile fileForController)
{
    if (!ModelState.IsValid)
    {
        return BadRequest(ModelState);
    }

    if (fileForController == null) throw new Exception("File is null");
    if (fileForController.Length == 0) throw new Exception("File is empty");

    var theImage = new Image();
    var path = Path.Combine("~ClientAppappassetsimages",fileForController.FileName);

    theImage.Url = path + fileForController.FileName;
    theImage.Title = fileForController.Name + "_" + fileForController.FileName;
    theImage.Caption = fileForController.Name + " and then a Surprice Caption";

    using (Stream stream = fileForController.OpenReadStream())
    {
        using (var reader = new BinaryReader(stream))
        {
            var fileContent = reader.ReadBytes((int)fileForController.Length);

            theImage.ImageFileContent = fileContent;
            _context.Images.Add(theImage);

            try
            {
                await _context.SaveChangesAsync();
            }
            catch (Exception ex)
            {
                throw new Exception(ex.Message);
            }
        }
    }
    return Ok(theImage);
}

<form action="gallery" name="fileUploadForm" method="post" enctype="multipart/form-data">
    <div class="col-md-6">
        <input #fileInput type="file" title="Choose Image to upload" />
        <button (click)="addFile()" class="btn btn-success">Add</button>
    </div>
</form>