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node red如何通过switch&case将json对象传递给多输出函数节点

node-red javascript

Jéan · 技术社区 · 6 年前

要使用具有多个输出的功能节点,可以按如下方式将消息传递到右侧输出:

switch (msg.payload) {
   case 1:
      var msg1 = {payload: foo.bar} ;
      break;
   case 2: 
      var msg2 = {payload: foo.bar2}
   break;
}
return [msg1,msg2];

但是,如果我想通过msg1/msg2传递json对象,它不会传递任何内容。以下两种方法都无法将json对象传递到每个msg的

var msg1 = {'payload.item1': xx, 'payload.item2': xy}; // or
var msg1 = {payload: {'item1': xx, 'item2': xy}};

知道如何将对象传递到多输出函数中吗?

这也不起作用:

var msg1 = 'a';
var msg2 = 'b';
var msg3 = 'c';

switch (msg.payload){
    case "1":
        msg1 = {payload: {'foo':1,'bar':10}};
        break;
    case "2":
       msg2 = {payload: {'foo':2,'bar':12}};
       break;
    case "3":
       msg1 = {payload: {'foo':3,'bar':13}};
       break;
}

return [msg1,msg2,msg3];

1 回复 | 直到 6 年前

AIOT MAKER 6 年前

上一个例子不起作用的原因很简单:您声明了msg1、msg2、msg3并为它们分配了字符串。节点red希望始终返回对象,而不是字符串。

因此,如果您替换:

var msg1 = 'a';
var msg2 = 'b';
var msg3 = 'c';

签署人:

var msg1 = {};
var msg2 = {};
var msg3 = {};

运行流时不会看到错误,但是..也许这不是你想要的。为了提供更准确的响应,有必要询问您希望在开关箱未选择的两个输出上交付什么?

一个更常见的解决方案,但不符合您的要求(使用具有多个输出的功能节点)将使用节点红色开关节点,如下流所示:

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