c# - Breeze - 如何在保存更改调用之前处理同一 View 中两个实体的状态

Question

我有 3 个实体 Project、Attachment 和 Messages。项目可以有多个附件和消息。

问题出在项目详细信息 View 上，我列出了它的消息和附件(如果有)或允许用户添加新附件和发布新消息。这是我的观点的快照

https://www.dropbox.com/s/9dfddv9oa7wo8rk/view.PNG

一旦用户添加新附件，通过管理器创建新的附件实体并在文件上传后，立即调用服务器保存更改。但是在项目详细 View 呈现之前，我还为消息创建了一个新实体，它在创建附件实体并调用保存更改时抛出验证错误，这很有意义。那么，我将如何处理这两个实体的状态？这是我的代码

模型类

项目.cs

Public class Project
{
     public int Id { get; set; }

            [Required, MaxLength(50)]
            public string Title { get; set; }

            [Required, StringLength(2000, ErrorMessage = "Enter {0} between {1} to {2} characters long", MinimumLength = 300)]
            public string Description { get; set; }

            [Required, Range(10, 10000)]
            public int Budget { get; set; }

            [Required]
            public DateTime Created { get; set; }

            public ICollection<Attachment> Attachment { get; set; }
            public ICollection<Messages> Messages { get; set; }

}

消息.cs

 public class Messages
    {
        public int Id { get; set; }
        public int ProjectId { get; set; }

        [Required]
        public string Text { get; set; }
        public Project Project { get; set; }
    }

附件.cs

 public class Attachment
    {
        public int Id { get; set; }
        public int ProjectId { get; set; }
        public string Name { get; set; }
        public string Path { get; set; }
        public Project Project { get; set; }
    }

Controller.js

 function activate() {

                getNewMessage();
                common.activateController([getProject()], controllerId)
                    .then(function () {

                    });
            }

     function addNewAttachment(file) {

        var attachment = datacontext.createNewAttachment();
        //other stuff

        return datacontext.save()
            .then(function () {


            });
    }



  function getNewMessage() {
            vm.message = datacontext.createNewMessage();
        }

datacontext.js

  function createNewMessage() {

        return manager.createEntity('Messages');
    }


    function createNewAttachment() {
        return manager.createEntity('Attachment');
    }

Answer 1

如果您想在不保存邮件的情况下创建附件，您可以这样做 -

function attachOnly(attachment) {
    // Put the attachment in an array to pass to your entity manager
    var entitiesToSave = [attachment];

    // em is your entity manager
    em.saveChanges(entitiesToSave).then(function(saveResult) {
        // save was successful
    }).fail(function (e) {
        // e is any exception that was thrown.
    });
}

本质上，这将仅您的附件对象调用保存更改，并忽略消息中的验证错误。