Question

谢谢我正在部署一个函数来限制push命令生成的子节点。我关注的链接code to limit child node现在我只是编辑这段代码，把我的自定义代码如下链接：

    'use strict';

const functions = require('firebase-functions');

// Max number of lines of the chat history.
const MAX_LOG_COUNT = 1;

// Removes siblings of the node that element that triggered the function if there are more than MAX_LOG_COUNT.
// In this example we'll keep the max number of chat message history to MAX_LOG_COUNT.
exports.truncate = functions.database.ref('/grid/{pushId}').onWrite((change) => {
  const parentRef = change.after.ref.parent;
  return parentRef.once('value').then((snapshot) => {
    if (snapshot.numChildren() >= MAX_LOG_COUNT) {
      let childCount = 0;
      const updates = {};
      snapshot.forEach((child) => {
        if (++childCount <= snapshot.numChildren() - MAX_LOG_COUNT) {
          updates[child.key] = null;
        }
      });
      // Update the parent. This effectively removes the extra children.
      return parentRef.update(updates);
    }
    return null;
  });
});

所以在这里我部署了限制子项的函数，但是在firebase日志中得到错误：

TypeError: Cannot read property 'ref' of undefined
    at exports.truncate.functions.database.ref.onWrite (/user_code/index.js:11:33)
    at Object.<anonymous> (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:59:27)
    at next (native)
    at /user_code/node_modules/firebase-functions/lib/cloud-functions.js:28:71
    at __awaiter (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:24:12)
    at cloudFunction (/user_code/node_modules/firebase-functions/lib/cloud-functions.js:53:36)
    at /var/tmp/worker/worker.js:700:26
    at process._tickDomainCallback (internal/process/next_tick.js:135:7)

Answer 1

不确定是否仍需要此功能。您是否已初始化Firebase App？添加以下行（如果尚未添加），然后再次检查。

const functions = require('firebase-functions');
const admin = require('firebase-admin');
admin.initializeApp(functions.config().firebase);

//Define your trigger

firebase云功能限制孩子

1 个答案: