Question

我正在尝试建立一个简单的物联网温度监测系统。 Node Red似乎是一个很好的解决方案。

我在ubuntu 16.04上安装了节点red和mongodb。当我尝试将数据存储到mongodb中时，它会成功存储，但是，当我尝试从我的数据库中获取数据时，我的调试选项卡上出现以下错误：[{"id":"845a2d0f.f529f","type":"debug","z":"175fe64a.2e87ba","name":"","active":true,"console":"false","complete":"false","x":698,"y":118,"wires":[]},{"id":"37b967b4.5953a8","type":"http in","z":"175fe64a.2e87ba","name":"/iot request","url":"/iot","method":"get","swaggerDoc":"","x":229.9517059326172,"y":314.0511169433594,"wires":[["70d77b6c.c2f234"]]},{"id":"70d77b6c.c2f234","type":"mongodb in","z":"175fe64a.2e87ba","mongodb":"5b5bee5b.f2593","name":"retrieve hello","collection":"test","operation":"find","x":472.9545593261719,"y":356.5880432128906,"wires":[["3b3c5324.f2f78c"]]},{"id":"3b3c5324.f2f78c","type":"http response","z":"175fe64a.2e87ba","name":"show hello","x":760.960205078125,"y":311.91192626953125,"wires":[]},{"id":"ac92efad.22272","type":"mqtt in","z":"175fe64a.2e87ba","name":"get outtemp","topic":"/sensors/esp0/temp0","qos":"2","broker":"fd4c9ee3.0aa1a","x":193,"y":118,"wires":[["845a2d0f.f529f","63a9e917.39f568"]]},{"id":"63a9e917.39f568","type":"mongodb out","z":"175fe64a.2e87ba","mongodb":"5b5bee5b.f2593","name":"store temp","collection":"test","payonly":true,"upsert":false,"multi":false,"operation":"store","x":406,"y":219,"wires":[]},{"id":"5b5bee5b.f2593","type":"mongodb","z":"","hostname":"127.0.0.1","port":"27017","db":"testdb","name":""},{"id":"fd4c9ee3.0aa1a","type":"mqtt-broker","z":"","broker":"localhost","port":"1883","clientid":"","usetls":false,"compatmode":true,"keepalive":"200","cleansession":true,"willTopic":"","willQos":"0","willPayload":"","birthTopic":"","birthQos":"0","birthPayload":""}]

这是我的节点：

$ aws cloudwatch get-metric-statistics --metric-name CPUUtilization --start-time 2017-03-20T23:18:00 --end-time 2017-03-25T23:18:00 --period 3600 --namespace AWS/EC2 --statistics Average --dimensions Name=i-014448f54423cc0,Value=i-abcdef

我是一个完整的begginer，节点红色和mongodb，有一些mqtt的经验。

我该如何解决这个问题？

Answer 1

在被knolleary指向正确的方向后，我找到了This post on the node-red mail list。

所以这就是我必须要做的事情：

在mongodb find block之前添加一个函数并输入此函数：

msg.limit = 5;
     msg.skip = 0;
     return msg;

节点红色MongoDB限制需要一个整数

1 个答案: