node-red - 类型错误 : Cannot assign to read only property '_msgid'

Question

我正在尝试 node-red...

我做这个网络查询 https://api.forecast.io/forecast/

这是给定的输出:

{"latitude":-25.74486,"longitude":28.18783,"timezone":"Africa/Johannesburg","offset":2,"currently":
{"time":1462871342,"summary":"Foggy","icon":"fog","precipIntensity":0,"precipProbability":0,
"temperature":18.08,"apparentTemperature":18.08,
"dewPoint":9.3,"humidity":0.57,"windSpeed":3.75,"windBearing":351,"visibility":2.78,
"cloudCover":0.23,"pressure":1024.87,"ozone":252.43}}

这似乎是正确的。

Parse Weather中的代码是

  //parse forecast.io message

 var weather = JSON.parse(msg.payload);

 return weather.currently.temperature;

我得到的错误是:

TypeError: Cannot assign to read only property '_msgid' of 19.49

这个值似乎还可以。

我做错了什么？

提前致谢。

Answer 1

问题出在您的 Parse Weather 函数中。您正在返回一个 int (18.08)，Function 节点需要返回一个 msg 对象。

尝试这样的事情:

var weather = JSON.parse(msg.payload);
msg.payload = weather.currently.temperature;

return msg;