BreezeJs：SaveChanges（）服务器响应被删除

1 回答

• 1

  我必须在我的项目中处理相同的场景 . 我采取的方法是两部分：

  • 为失败的ajax请求添加自动重试 . 我正在使用jQuery和jQuery，所以我用google搜索“jQuery retry ajax” . 有许多不同的实现，我的有点自定义，所有都围绕着劫持onerror回调以及延迟的失败处理程序来注入重试逻辑 . 我确信Angular会有类似的方法来重试丢弃的请求 .

  • 在saveChanges失败处理程序中，添加如下逻辑：

  ...

  function isConcurrencyException(reason: any) {
      return reason && reason.message && /Store update, insert, or delete statement affected an unexpected number of rows/.test(reason.message);
  }
  
  function isConnectionFailure(reason: any): boolean {
      return reason && reason.hasOwnProperty('status') && reason.status === 0
  }
  
  entityManager.saveChanges()
     .then(... yay ...)
     .fail(function(reason) {
         if (isConnectionFailure(reason)) {
             // retry attempts failed to reach server.
             // notify user and save to local storage....
             return;
         }
  
         if (isConcurrencyException(reason)) {
             // EF is not letting me save the entities again because my previous save (or another user's save) moved the concurrency stamps on the record.  There's also the possibility that a record I'm try to save was deleted by another user.
  
             // recover... in my case I kept it simple and simply attempt to reload the entity.  If nothing is returned I know the entity was deleted.  Otherwise I now have the latest version.  In either case a message is shown to the user.  
             return; 
         }
  
         if (reason.entityErrors) {
             // We have an "entityErrors" property... this means the saved failed due to server-side validation errors.
             // do whatever you do to handle validation errors...
             return;           
         }
  
         // an unexpected exception.  let it bubble up.
         throw reason;    
     })
     .done();  // terminate the promise chain (may not be an equivalent in Angular, not sure).
  

  ---

  测试不稳定连接的方法之一是使用Fiddler's AutoResponder选项卡 . 使用与您的breeze路由匹配的正则表达式设置 *.drop 规则，并在要模拟已删除的请求时检查"Enable Automatic Responses"框 .

  

  ---

  这是一个有点混乱的问题需要解决 - 没有一个尺寸适合所有答案，希望这有帮助 .

  ---

  NOTE

  沃德在下面的评论中提出了一个很好的观点 . 这种方法不适用于在服务器上生成实体主键的情况（如果您的数据库使用PK的标识列，则会出现这种情况），因为重试逻辑可能导致重复插入 .

  回复于 2024-05-06T04:01:00+08:00