Parse.Cloud.beforeSave 无法在正在创建的对象上设置新字段

Question

我在 Parse-Server 上的 Parse.Cloud.beforeSave 函数中遇到了一个小问题。这条线让我感到困惑：

request.object.set("dbCount", 0);

之前一直有效。但是自从我进行了服务器更新后，按照 HEROKU 的要求进入 heroku-18 堆栈（cedar-14 堆栈即将结束生命）。它不再有效。

此行的目的是在数据库中存储新项目时将计数器初始化为零。但是，尽管该项目已按预期创建，但缺少字段 "dbCount"。这是为什么？创建字段的正确代码是什么？

作为参考，这里是beforeSave函数的相关代码：

Parse.Cloud.beforeSave("TheCollection", async (request) => {
 if (!request.object.isNew()) return;
 var query;
 query = new Parse.Query("TheCollection");
 query.equalTo("TITLE",request.object.get("TITLE"));

 await query.find().then
 (function(resUnit) {
  // If there is already a Unit with the same Title, we return an error.
  if (resUnit.length) throw "TITLE-USED";

  var query;
  query = new Parse.Query("TheCollection");
  var token = request.user.getSessionToken();
  query.find({sessionToken: token}).then
  (function(resUnit) {
    ... some useful processing ...
    // This next line is not working as it used to.
    request.object.set("dbCount", 0);
   });
  });
 });

Answer 1

您可能遗漏了 "return" 并且保存在您的承诺解决之前发生。我还看到您在嵌套范围内使用相同的变量 "resUnit"，这可能会混淆它的使用。

Parse.Cloud.beforeSave("TheCollection", async (request) => {
 if (!request.object.isNew()) return;
 var query;
 query = new Parse.Query("TheCollection");
 query.equalTo("TITLE",request.object.get("TITLE"));

 await query.find().then
 (function(resUnit) {
  // If there is already a Unit with the same Title, we return an error.
  if (resUnit.length) throw "TITLE-USED";

  var query;
  query = new Parse.Query("TheCollection");
  var token = request.user.getSessionToken();
  >>>> return <<<<< query.find({sessionToken: token}).then
  (function(resUnit) {
    ... some useful processing ...
    // This next line is not working as it used to.
    request.object.set("dbCount", 0);
   });
  });
 });

如果您想更进一步，我会充分利用 async 和 await 来像这样扁平化您的代码。通过使用平面代码，您可以消除很多导致错误的混乱情况

Parse.Cloud.beforeSave("TheCollection", async (request) => {
 if (!request.object.isNew()) return;
 const query = new Parse.Query("TheCollection");
 query.equalTo("TITLE",request.object.get("TITLE"));

 const resUnit1 = await query.first()
 // If there is already a Unit with the same Title, we return an error.
 if (resUnit) throw "TITLE-USED";

  const query2 = new Parse.Query("TheCollection");
  const resUnit2 = await query2.find({sessionToken: request.user.getSessionToken()})
  ... some useful processing ...
  request.object.set("dbCount", 0);
 });

Parse.Cloud.beforeSave 无法在正在创建的对象上设置新字段

Parse.Cloud.beforeSave not able to set a new field on an object being created

javascript

parse-server

mlab

heroku-api

parse-cloud-code