javascript - 使用 Ajax 从 Web 服务返回 JSON 而不是 XML 而 'contentType' 是 'false'

Question

我进行了 AJAX 调用以将图像文件发送到我的网络服务 (.asmx) 方法之一。一切正常，但问题是 Web 服务返回 XML 而不是 JSON，因为我必须将 'contentType' 设置为 'false'，否则无法发送文件. (如果我将 contentType 设置为 application/json; charset=utf-8，它会返回 JSON，但我无法这样做，因为我正在发送文件。)

这是我的 JavaScript:

function setAvatar(imageFile, successCallback) {
var formData = new FormData();
formData.append("UploadedAvatar", imageFile);
$.ajax({
    type: "POST",
    url: "/Services/UserService.asmx/SetAvatar",
    contentType: false,
    processData: false,
    dataType: 'json',
    data: formData,
    success: function (result) {
        alert(result.d);
        alert(result.d.IsSuccessful);
        if (typeof successCallback === 'function')
            successCallback(result);
    }
});

和网络服务方法:

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public Result SetAvatar()
{
    HttpPostedFile postedFile = HttpContext.Current.Request.Files["UploadedAvatar"];
    Image avatar = Image.FromStream(postedFile.InputStream, true, true);
    avatar = new Bitmap(avatar, new Size(150, 150));
    avatar.Save(Path.Combine(path, $"Avatar-Small.jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);

    return new Result(true, Messages.AvatarSavedSuccessfully);
}

Answer 1

在发出期望 JSON 的请求时设置 Accept header

$.ajax({
    type: "POST",
    url: "/Services/UserService.asmx/SetAvatar",
    headers: { //SET ACCEPT HEADER
        Accept : "application/json; charset=utf-8",
    },  
    contentType: false,
    processData: false,
    dataType: 'json',
    data: formData,
    success: function (result) {
        alert(result.d);
        alert(result.d.IsSuccessful);
        if (typeof successCallback === 'function')
            successCallback(result);
    }
});

在服务器端，使用 Json.Net 你可以序列化结果

[WebMethod]
[ScriptMethod(ResponseFormat = ResponseFormat.Json)]
public string SetAvatar() {
    HttpPostedFile postedFile = HttpContext.Current.Request.Files["UploadedAvatar"];
    Image avatar = Image.FromStream(postedFile.InputStream, true, true);
    avatar = new Bitmap(avatar, new Size(150, 150));
    avatar.Save(Path.Combine(path, $"Avatar-Small.jpg"), System.Drawing.Imaging.ImageFormat.Jpeg);

    var result = new Result(true, Messages.AvatarSavedSuccessfully);
    return JsonConvert.SerializeObject(result);
}

这应该允许响应是所需的类型