attachment(非attachmentSimple)相关的组件js中怎么清空bind-ref关联的关系的数据

var data = this.comp("bizData1");
data.setValue("fName","");

但是附件组件对应的关系存的json传不能用setValue一个空值的方式清空数据，要清空数据参考

	Model.prototype.button1Click = function(event) {
		var attachmentPC = this.comp("attachmentImage1");//获取附件组件对象
		var data = this.comp("mainData");//获取data
		var fAttachmentPicture = data.getValue("fAttachmentPicture");//获取附件组件对应的关系的值
		var jsonList = eval("(" + fAttachmentPicture + ")");//把json串转换为json对象
		if (jsonList.length > 0) {
			for (var i = 0; i < jsonList.length; i++) {
				var docID = jsonList[i]["docID"];
				attachmentPC.setValue("delete", docID);//把json中存的docID赋值给附件组件对象的delete
				var items = attachmentPC.changeLog.items;//获取附件对象中存储的改变记录,这个记录是通过附件提供的按钮上传、删除等记录		
				for ( var item in items) {
					if (items[item].doc_id == docID) {
						attachmentPC.changeLog.items.splice(item, 1);//从改变记录中把数据也清除
						
					}
				}
			}
		}
	};