c# - 来自 JSON 的 ASP.NET MVC 4 递归模型绑定(bind)

Question

我正在使用 Fabric.js , 将绘图对象保存到数据库中。我们经常使用组，从而导致多层嵌套绘图对象。我已经创建了与从 canvas 对象发回的值相匹配的类，并且它正确地绑定(bind)了我绘图中的顶级项目。但是，它没有绑定(bind)任何子项，我不知道出了什么问题。

我的模型(为了简短起见删除了一些属性:

public class DrawingObj
{
    public int ParentID { get; set; } //will be populated manually

    [JsonProperty("type")]
    public string Type { get; set; }

    [JsonProperty("originX")]
    public string OriginX { get; set; }

    [JsonProperty("originY")]
    public string OriginY { get; set; }

    ....

    [JsonProperty("objects")]
    public ICollection<DrawingObj> ChildObj { get; set; }

    [JsonProperty("points")]
    public ICollection<Point> Points { get; set; }
}

public class Point
{
    [JsonProperty("type")]
    public string Type { get; set; }

    [JsonProperty("x")]
    public decimal X { get; set; }

    [JsonProperty("y")]
    public decimal Y { get; set; }
}

这是 Json。抱歉，有很多。

{"objects":[{"type":"group","originX":"center","originY":"center","left":461,"top":278,"width":126,"height":247.5,"fill":"rgb(0,0,0)","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","objects":[{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":126,"height":247.5,"fill":"white","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-63,"y":-123.75},{"type":"line","x":-63,"y":123.75},{"type":"line","x":63,"y":123.75},{"type":"line","x":63,"y":-123.75},{"type":"line","x":-63,"y":-123.75}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":125,"height":246.25,"fill":"white","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-62.5,"y":-123.125},{"type":"line","x":-62.5,"y":123.125},{"type":"line","x":62.5,"y":123.125},{"type":"line","x":62.5,"y":-123.125},{"type":"line","x":-62.5,"y":-123.125}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":111.38,"height":231,"fill":"white","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-55.6875,"y":-115.5},{"type":"line","x":-55.6875,"y":115.5},{"type":"line","x":55.6875,"y":115.5},{"type":"line","x":55.6875,"y":-115.5},{"type":"line","x":-55.6875,"y":-115.5}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":96,"height":215.25,"fill":"#C9C9C9","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-48,"y":-107.625},{"type":"line","x":-48,"y":107.625},{"type":"line","x":48,"y":107.625},{"type":"line","x":48,"y":-107.625},{"type":"line","x":-48,"y":-107.625}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":91.5,"height":210.75,"fill":"black","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-45.75,"y":-105.375},{"type":"line","x":-45.75,"y":105.375},{"type":"line","x":45.75,"y":105.375},{"type":"line","x":45.75,"y":-105.375},{"type":"line","x":-45.75,"y":-105.375}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":90,"height":209.62,"fill":"#A5EDF2","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-45,"y":-104.811},{"type":"line","x":-45,"y":104.811},{"type":"line","x":45,"y":104.811},{"type":"line","x":45,"y":-104.811},{"type":"line","x":-45,"y":-104.811}]},{"type":"custom-circle","originX":"center","originY":"center","left":0,"top":0,"width":20,"height":20,"fill":"white","stroke":2,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","radius":10},{"type":"named-text","originX":"center","originY":"center","left":0,"top":0,"width":6,"height":15.6,"fill":"black","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","text":"1","fontSize":12,"fontWeight":"normal","fontFamily":"Times New Roman","fontStyle":"","lineHeight":1.3,"textDecoration":"","textAlign":"left","path":null,"textBackgroundColor":"","useNative":true,"name":"label"}]},{"type":"group","originX":"center","originY":"center","left":598,"top":277,"width":126,"height":247.5,"fill":"rgb(0,0,0)","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","objects":[{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":126,"height":247.5,"fill":"white","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-63,"y":-123.75},{"type":"line","x":-63,"y":123.75},{"type":"line","x":63,"y":123.75},{"type":"line","x":63,"y":-123.75},{"type":"line","x":-63,"y":-123.75}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":125,"height":246.25,"fill":"white","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-62.5,"y":-123.125},{"type":"line","x":-62.5,"y":123.125},{"type":"line","x":62.5,"y":123.125},{"type":"line","x":62.5,"y":-123.125},{"type":"line","x":-62.5,"y":-123.125}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":111.38,"height":231,"fill":"white","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-55.6875,"y":-115.5},{"type":"line","x":-55.6875,"y":115.5},{"type":"line","x":55.6875,"y":115.5},{"type":"line","x":55.6875,"y":-115.5},{"type":"line","x":-55.6875,"y":-115.5}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":96,"height":215.25,"fill":"#C9C9C9","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-48,"y":-107.625},{"type":"line","x":-48,"y":107.625},{"type":"line","x":48,"y":107.625},{"type":"line","x":48,"y":-107.625},{"type":"line","x":-48,"y":-107.625}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":91.5,"height":210.75,"fill":"black","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-45.75,"y":-105.375},{"type":"line","x":-45.75,"y":105.375},{"type":"line","x":45.75,"y":105.375},{"type":"line","x":45.75,"y":-105.375},{"type":"line","x":-45.75,"y":-105.375}]},{"type":"rounded-polygon","originX":"center","originY":"center","left":0,"top":0,"width":90,"height":209.62,"fill":"#A5EDF2","stroke":1,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","points":[{"type":"line","x":-45,"y":-104.811},{"type":"line","x":-45,"y":104.811},{"type":"line","x":45,"y":104.811},{"type":"line","x":45,"y":-104.811},{"type":"line","x":-45,"y":-104.811}]},{"type":"custom-circle","originX":"center","originY":"center","left":0,"top":0,"width":20,"height":20,"fill":"white","stroke":2,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","radius":10},{"type":"named-text","originX":"center","originY":"center","left":0,"top":0,"width":6,"height":15.6,"fill":"black","stroke":null,"strokeWidth":1,"strokeDashArray":null,"strokeLineCap":"butt","strokeLineJoin":"miter","strokeMiterLimit":10,"scaleX":1,"scaleY":1,"angle":0,"flipX":false,"flipY":false,"opacity":1,"shadow":null,"visible":true,"clipTo":null,"backgroundColor":"","text":"2","fontSize":12,"fontWeight":"normal","fontFamily":"Times New Roman","fontStyle":"","lineHeight":1.3,"textDecoration":"","textAlign":"left","path":null,"textBackgroundColor":"","useNative":true,"name":"label"}]}],"background":""}

Ajax 调用:

    var jsontext = JSON.stringify(canvas);

    $.ajax({
        url: '/Project/SaveDrawing/',
        data: jsontext,
        contentType: 'application/json; charset=utf-8',
        dataType: 'json',
        type: 'post',
        success: onSaved,
        error: function (data, textStatus) { alert(textStatus); }
    });

Controller :

    [HttpPost]
    public JsonResult SaveDrawing(ICollection<DrawingObj> objects)
    {
        try
        {
            if (objects != null)
            {
                bool saved = Drawing.SaveDrawing(objects);
                return Json(new { success = saved });
            }
        }
        catch (Exception ex)
        {
            error = ex.Message;
        }
        return Json(new { success = false, error = error });
    }

所以我的两个顶级项目完全按照预期绑定(bind)，但 ChildObj 和 Points 都是空的。我不明白为什么这些集合没有约束力，因为我相信我的命名是正确的。

在此先感谢您的帮助。

Answer 1

很明显，ASP.NET MVC DefaultModelBinder 在那里无法正常工作。

一种方法是为您的对象创建一个自定义模型 Binder 。首先，您必须添加一个额外的类以将您发布到 Controller 的 JSON 正确映射。

[JsonObject]
public class ContainerObj
{
    [JsonProperty("objects")]
    public ICollection<DrawingObj> Objects { get; set; }

    [JsonProperty("background")]
    public string Background { get; set; }
}

然后您将创建一个自定义模型绑定(bind)器以使用 JSON.NET 将该对象反序列化为您需要的对象:

public class ContainerObjModelBinder : DefaultModelBinder
{
    public override object BindModel(ControllerContext controllerContext, ModelBindingContext bindingContext)
    {
        if (bindingContext.ModelType == typeof(ContainerObj))
        {
            var data = GetDocumentContents(controllerContext.HttpContext.Request);

            return JsonConvert.DeserializeObject<ContainerObj>(data);
        }

        return base.BindModel(controllerContext, bindingContext);
    }

    private string GetDocumentContents(System.Web.HttpRequestBase Request)
    {
        string documentContents;
        using (var receiveStream = Request.InputStream)
        {
            using (var readStream = new StreamReader(receiveStream, Encoding.UTF8))
            {
                readStream.BaseStream.Seek(0, SeekOrigin.Begin);
                documentContents = readStream.ReadToEnd();
            }
        }
        return documentContents;
    }
}

然后您将在 Global.asax 中注册此自定义模型绑定(bind)器:

 ModelBinders.Binders.Add(typeof(ContainerObj), new ContainerObjModelBinder());

最后，您的 Controller 会自动识别它需要使用自定义模型绑定(bind)器:

[HttpPost]
public JsonResult SaveDrawing(ContainerObj data)
{
    // Request processing
}