- 1. 前言
- 2. YAMLformat的data处理
- 3. CSVformat的data处理
- 4. csv转json
前言
在前面的章节中我介绍了如何在Node-RED中处理json与xmlformat的data。但随后又有读者向我询问，
在node-red中如何处理yamlformat的data，以及csvformat的data。yamlformat的data是随着这几年云原生而大行其道的data format。因为不需要中括号，format优雅，而收到开发人员的喜爱。云原生中的资源定义都可以使用yaml文件来定义。CSVformat是实施分隔的Text文件。可以与excel中的data互相转化。
YAMLformat的data处理
处理yamlformatdata主要使用的是yaml节点。该节点可以实现 在YAMLformat的字符串及其JavaScript对象即jsondata format之间相互转换。
输入：
payload object | 字符串
JavaScript 对象或YAML字符串。
输出：
payload object | 字符串
● 如果输入是YAML字符串，它将尝试将其Parse为JavaScript对象。
● 如果输入是JavaScript对象，它将创建一个YAML字符串。
以下是一个示例：
可以将yaml的字符串转换为json对象
如字符串变量 {"a":1, "b":[1,2,3]} 转换成yaml 就变成了
a: 1
b:
- 1
- 2
- 3
完整的data流
[{"id":"f231967.0251a68","type":"inject","z":"64133d39.bb0394","name":"YAML String","topic":"","payload":"{\"a\":1}","payloadType":"str","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":320,"wires":[["a0110756.ecfa48"]]},
{"id":"8f8f31b7.1f916","type":"debug","z":"64133d39.bb0394","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":590,"y":320,"wires":[]},
{"id":"5138ba3.c972444","type":"inject","z":"64133d39.bb0394","name":"Object","topic":"","payload":"{\"a\":1, \"b\":[1,2,3]}","payloadType":"json","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":90,"y":360,"wires":[["2fa653cc.60d3dc"]]},
{"id":"50f2f4c.4a6e60c","type":"debug","z":"64133d39.bb0394","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":430,"y":360,"wires":[]},
{"id":"a0110756.ecfa48","type":"template","z":"64133d39.bb0394","name":"","field":"payload","fieldType":"msg","format":"yaml","syntax":"plain","template":"a: 1\nb:\n - 1\n - 2\n - 3","output":"str","x":280,"y":320,"wires":[["104b80e2.51068f"]]},
{"id":"2fa653cc.60d3dc","type":"yaml","z":"64133d39.bb0394","property":"payload","name":"","x":250,"y":360,"wires":[["50f2f4c.4a6e60c"]]},
{"id":"104b80e2.51068f","type":"yaml","z":"64133d39.bb0394","property":"payload","name":"","x":430,"y":320,"wires":[["8f8f31b7.1f916"]]}]CSVformat的data处理
对于CSVformat，一种是要输出CSVformat的data，如，每行以逗号隔开。CSVformat的data处理离不开node-red自带的csv节点。
在CSVformat的字符串及其JavaScript对象表示形式之间进行相互转换。
输入：
payload object | 数组 | 字符串
JavaScript对象，数组或CSV字符串。
输出：
payload object | 数组 | 字符串
- 如果输入是字符串，它将尝试将其Parse为CSV，并为每行创建键/值对的JavaScript对象。然后该节点将为每行send一条消息，或者send一条包含对象数组的消息。
- 如果输入是JavaScript对象，它将尝试构建CSV字符串。
- 如果输入是简单值的数组，则将构建单行CSV字符串。
- 如果输入是数组数组或对象数组，则会创建多行CSV字符串。
列模板可以包含列名称的有Sequence表。将CSV转换为对象时，列名将用作属性名称。或者也可以从CSV的第一行中获取列名称。
转换为CSV时，列模板用于标识从对象中提取的属性以及提取的顺序。
如果输入是数组，则列模板仅用于有选择地生成一行列标题。
只要正确设置parts属性，该节点就可以接受多部分输入。
如果输出多个消息，则将设置其parts属性并形成完整的消息Sequence。
注意：列模板必须用逗号分隔，即使data中已有了其他分隔符。
CSV 节点的配置页面
csv节点可以将jsondata format，转为为字符串。
如
{
a: 10,
b: 20,
c: 30
}通过CSV可以转化为"10,20,30\n"
你也可以通过它来转化数组
如下面的数组，
[
{ a: 80, b: 18, c: 2},
{ a: 52, b: 36, c: 10},
{ a: 91, b: 18, c: 61},
{ a: 32, b: 47, c: 65},
]通过CSV可以转化为
a,b,c
80,18,2
52,36,10
91,18,61
32,47,65完整的例子流代码
[{"id":"457d9ad6.b737b4","type":"inject","z":"64133d39.bb0394","name":"single","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":90,"y":640,"wires":[["1e05fafd.887b05"]]},{"id":"1e05fafd.887b05","type":"change","z":"64133d39.bb0394","name":"Generate single payload","rules":[{"t":"set","p":"payload","pt":"msg","to":"{ \"a\":$floor(100*$random()),\"b\":$floor(100*$random()),\"c\":$floor(100*$random())}","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":270,"y":640,"wires":[["e9546682.b39898"]]},
{"id":"e9546682.b39898","type":"csv","z":"64133d39.bb0394","name":"","sep":",","hdrin":"","hdrout":false,"multi":"one","ret":"\\n","temp":"a,b,c","skip":"0","x":450,"y":640,"wires":[["f83ad3b0.78d32"]]},
{"id":"f83ad3b0.78d32","type":"debug","z":"64133d39.bb0394","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":590,"y":640,"wires":[]},
{"id":"ae242f2c.d1c8a","type":"inject","z":"64133d39.bb0394","name":"array","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":90,"y":700,"wires":[["7535f521.4a88bc"]]},
{"id":"7535f521.4a88bc","type":"change","z":"64133d39.bb0394","name":"Generate array payload","rules":[{"t":"set","p":"payload","pt":"msg","to":"[\t { \"a\":$floor(100*$random()),\"b\":$floor(100*$random()),\"c\":$floor(100*$random())},\t { \"a\":$floor(100*$random()),\"b\":$floor(100*$random()),\"c\":$floor(100*$random())},\t { \"a\":$floor(100*$random()),\"b\":$floor(100*$random()),\"c\":$floor(100*$random())},\t { \"a\":$floor(100*$random()),\"b\":$floor(100*$random()),\"c\":$floor(100*$random())}\t]","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":270,"y":700,"wires":[["f4e0465f.ef0338"]]},
{"id":"f4e0465f.ef0338","type":"csv","z":"64133d39.bb0394","name":"","sep":",","hdrin":"","hdrout":true,"multi":"one","ret":"\\n","temp":"a,b,c","skip":"0","x":450,"y":700,"wires":[["6eb67fdf.58626"]]},
{"id":"6eb67fdf.58626","type":"debug","z":"64133d39.bb0394","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":590,"y":700,"wires":[]}]
csv转json
除此之外CSV节点还可以将CSVformat的data 进行转化，转成成JSONdata。
这是一个CSVformat的data
a,b,c
80,18,2
52,36,10
91,18,61
32,47,65通过CSV节点，它可以转化为标准的JSONformat
[
{ a: 80, b: 18, c: 2},
{ a: 52, b: 36, c: 10},
{ a: 91, b: 18, c: 61},
{ a: 32, b: 47, c: 65},
]
发表回复