Node-RED：解释 REST 服务 URL

Question

我目前正在使用 IBM Bluemix IoT 快速入门进行一些实验。对于那些不知道这一点的人，它是一个物联网传感器模拟器，可用于控制温度和湿度值。

我希望使用 Web 服务连接器来查找温度读数。我将如何解释这个服务 URL？

另外（但不那么重要！）我看到网站 /test/ 无法显示温度读数。关于为什么的任何想法？

下面是web服务用来显示温度的json

[
  {
    "id": "e42c6f27.46cca",
    "type": "function",
    "z": "3ed49b1f.4c1164",
    "name": "temp",
    "func": "return {payload:msg.payload.d.temp};",
    "outputs": 1,
    "noerr": 0,
    "x": 422.5,
    "y": 775,
    "wires": [
      [
        "c76cd036.bc2ba"
      ]
    ]
  },
  {
    "id": "f47256cd.a18b78",
    "type": "template",
    "z": "3ed49b1f.4c1164",
    "name": "",
    "field": "payload",
    "fieldType": "msg",
    "format": "handlebars",
    "syntax": "mustache",
    "template": "The temperature is\n{{payload}}\n",
    "output": "str",
    "x": 775,
    "y": 953,
    "wires": [
      [
        "22b54d74.028ae2"
      ]
    ]
  },
  {
    "id": "22b54d74.028ae2",
    "type": "http response",
    "z": "3ed49b1f.4c1164",
    "name": "",
    "statusCode": "",
    "headers": {

    },
    "x": 1064,
    "y": 955,
    "wires": [

    ]
  },
  {
    "id": "243d218a.fe14ae",
    "type": "http in",
    "z": "3ed49b1f.4c1164",
    "name": "",
    "url": "test",
    "method": "get",
    "upload": false,
    "swaggerDoc": "",
    "x": 432,
    "y": 993,
    "wires": [
      [
        "f47256cd.a18b78"
      ]
    ]
  },
  {
    "id": "429ffb9e.7ed404",
    "type": "ibmiot in",
    "z": "3ed49b1f.4c1164",
    "authentication": "quickstart",
    "apiKey": "",
    "inputType": "evt",
    "deviceId": "3bd1c8df5ed2",
    "applicationId": "",
    "deviceType": "iotqs-sensor",
    "eventType": "+",
    "commandType": "",
    "format": "json",
    "name": "IBM IoT App In",
    "service": "quickstart",
    "allDevices": false,
    "allApplications": false,
    "allDeviceTypes": true,
    "allEvents": true,
    "allCommands": false,
    "allFormats": false,
    "x": 269,
    "y": 550,
    "wires": [
      [
        "55064d15.005804",
        "c34674a2.7ea0d8",
        "2356b867.1c3d68",
        "c7ee16c4.493fc8",
        "e42c6f27.46cca"
      ]
    ]
  },
  {
    "id": "55064d15.005804",
    "type": "debug",
    "z": "3ed49b1f.4c1164",
    "name": "name",
    "active": true,
    "complete": "payload.d.name",
    "x": 717.5,
    "y": 551,
    "wires": [

    ]
  },
  {
    "id": "c34674a2.7ea0d8",
    "type": "debug",
    "z": "3ed49b1f.4c1164",
    "name": "Temperature",
    "active": true,
    "complete": "payload.d.temp",
    "x": 717.5,
    "y": 651,
    "wires": [

    ]
  },
  {
    "id": "2356b867.1c3d68",
    "type": "debug",
    "z": "3ed49b1f.4c1164",
    "name": "Humidity",
    "active": true,
    "complete": "payload.d.humidity",
    "x": 717.5,
    "y": 751,
    "wires": [

    ]
  },
  {
    "id": "c7ee16c4.493fc8",
    "type": "debug",
    "z": "3ed49b1f.4c1164",
    "name": "Object Temperature",
    "active": true,
    "complete": "payload.d.objectTemp",
    "x": 717.5,
    "y": 851,
    "wires": [

    ]
  },
  {
    "id": "c76cd036.bc2ba",
    "type": "json",
    "z": "3ed49b1f.4c1164",
    "name": "",
    "pretty": true,
    "x": 531,
    "y": 894,
    "wires": [
      [
        "f47256cd.a18b78"
      ]
    ]
  }
]

Answer 1

此流程存在一些问题：

• JSON 节点不是必需的，因为 msg.payload 已经是 json
• iot 节点的输出读数正在发送到 http response 节点，仅当流从 API 调用返回结果时才需要这样做
• http in 节点的输出不包含 msg.payload，因此 template 节点没有要格式化的内容

这是一种不同的方法，我相信它可以满足您的需求：

• 将输出对象msg.payload.d 存储到名为“lastReadings”的流上下文变量中
• 使用带有 url /last/:type 的 http in 节点作为 api 端点来检索给定传感器类型的最后一个值（如果您安装了 node-red-node-swagger，您可以测试直接从右侧边栏端点）
• 使用 switch 节点根据传感器类型路由 api 调用，以检索最后的读数并通过 http response 节点返回输出字符串

需要注意的几点： 如果您的 settings.js 包含 httpRoot 或 httpNodeRoot url 前缀，这将在您的 api url 之前 - 这可能是您没有结果的原因尝试访问 URL“http://localhost:1880/test/”时。检查 http in 节点上的注释是否有类似的内容：

url 将相对于 /red。

在这种情况下，您需要使用 api url "http://localhost:1880/red/test/"

这是我创建的流程，以及用于测试您的值的注入节点（因为我没有可用的 ibmiot 输入节点）：

[
{
    "id": "5ebe7dff.780724",
    "type": "template",
    "z": "7299298e.a9f058",
    "name": "output value",
    "field": "payload",
    "fieldType": "msg",
    "format": "handlebars",
    "syntax": "mustache",
    "template": "Last {{sensor}} reading:\n{{payload}}\n",
    "output": "str",
    "x": 630,
    "y": 720,
    "wires": [
        [
            "cb13c651.0ef458",
            "efabaec0.9bd7a"
        ]
    ]
},
{
    "id": "cb13c651.0ef458",
    "type": "http response",
    "z": "7299298e.a9f058",
    "name": "",
    "statusCode": "",
    "headers": {},
    "x": 790,
    "y": 760,
    "wires": []
},
{
    "id": "361c51b4.f519ae",
    "type": "http in",
    "z": "7299298e.a9f058",
    "name": "",
    "url": "/last/:type",
    "method": "get",
    "upload": false,
    "swaggerDoc": "59b72c5b.bc0fb4",
    "x": 150,
    "y": 640,
    "wires": [
        [
            "c2fb1169.b76e8",
            "61234f00.7faf1"
        ]
    ]
},
{
    "id": "884f3eb9.e22be",
    "type": "debug",
    "z": "7299298e.a9f058",
    "name": "payload.d values",
    "active": true,
    "console": "false",
    "complete": "payload.d",
    "x": 470,
    "y": 480,
    "wires": []
},
{
    "id": "fef6db49.919728",
    "type": "comment",
    "z": "7299298e.a9f058",
    "name": "Save the last readings to flow context",
    "info": "",
    "x": 210,
    "y": 440,
    "wires": []
},
{
    "id": "81bfb514.a63348",
    "type": "change",
    "z": "7299298e.a9f058",
    "name": "save readings",
    "rules": [
        {
            "t": "set",
            "p": "lastReadings",
            "pt": "flow",
            "to": "payload.d",
            "tot": "msg"
        }
    ],
    "action": "",
    "property": "",
    "from": "",
    "to": "",
    "reg": false,
    "x": 460,
    "y": 520,
    "wires": [
        []
    ]
},
{
    "id": "9573eab5.84e548",
    "type": "comment",
    "z": "7299298e.a9f058",
    "name": "API endpoints to retrieve sensor values",
    "info": "",
    "x": 210,
    "y": 600,
    "wires": []
},
{
    "id": "c2fb1169.b76e8",
    "type": "switch",
    "z": "7299298e.a9f058",
    "name": "sensor type",
    "property": "req.params.type",
    "propertyType": "msg",
    "rules": [
        {
            "t": "eq",
            "v": "temp",
            "vt": "str"
        },
        {
            "t": "eq",
            "v": "humidity",
            "vt": "str"
        },
        {
            "t": "eq",
            "v": "objectTemp",
            "vt": "str"
        },
        {
            "t": "else"
        }
    ],
    "checkall": "true",
    "outputs": 4,
    "x": 250,
    "y": 700,
    "wires": [
        [
            "4eb4657b.cd0b0c"
        ],
        [
            "801c0b28.320308"
        ],
        [
            "a7833d28.f58f"
        ],
        [
            "e30f26ce.a084b8"
        ]
    ]
},
{
    "id": "4eb4657b.cd0b0c",
    "type": "change",
    "z": "7299298e.a9f058",
    "name": "Temperature",
    "rules": [
        {
            "t": "set",
            "p": "sensor",
            "pt": "msg",
            "to": "Temperature",
            "tot": "str"
        },
        {
            "t": "set",
            "p": "payload",
            "pt": "msg",
            "to": "lastReadings.temp",
            "tot": "flow"
        }
    ],
    "action": "",
    "property": "",
    "from": "",
    "to": "",
    "reg": false,
    "x": 450,
    "y": 680,
    "wires": [
        [
            "5ebe7dff.780724"
        ]
    ]
},
{
    "id": "801c0b28.320308",
    "type": "change",
    "z": "7299298e.a9f058",
    "name": "Humidity",
    "rules": [
        {
            "t": "set",
            "p": "sensor",
            "pt": "msg",
            "to": "Humidity",
            "tot": "str"
        },
        {
            "t": "set",
            "p": "payload",
            "pt": "msg",
            "to": "lastReadings.humidity",
            "tot": "flow"
        }
    ],
    "action": "",
    "property": "",
    "from": "",
    "to": "",
    "reg": false,
    "x": 440,
    "y": 720,
    "wires": [
        [
            "5ebe7dff.780724"
        ]
    ]
},
{
    "id": "a7833d28.f58f",
    "type": "change",
    "z": "7299298e.a9f058",
    "name": "Object Temp",
    "rules": [
        {
            "t": "set",
            "p": "sensor",
            "pt": "msg",
            "to": "Object Temp",
            "tot": "str"
        },
        {
            "t": "set",
            "p": "payload",
            "pt": "msg",
            "to": "lastReadings.objectTemp",
            "tot": "flow"
        }
    ],
    "action": "",
    "property": "",
    "from": "",
    "to": "",
    "reg": false,
    "x": 450,
    "y": 760,
    "wires": [
        [
            "5ebe7dff.780724"
        ]
    ]
},
{
    "id": "61234f00.7faf1",
    "type": "debug",
    "z": "7299298e.a9f058",
    "name": "API params",
    "active": false,
    "console": "false",
    "complete": "true",
    "x": 450,
    "y": 640,
    "wires": []
},
{
    "id": "efabaec0.9bd7a",
    "type": "debug",
    "z": "7299298e.a9f058",
    "name": "API out",
    "active": true,
    "console": "false",
    "complete": "payload",
    "x": 800,
    "y": 720,
    "wires": []
},
{
    "id": "b019dd18.1806e",
    "type": "inject",
    "z": "7299298e.a9f058",
    "name": "test values",
    "topic": "",
    "payload": "{\"d\":{\"temp\":21,\"humidity\":69,\"objectTemp\":\"NA\"}}",
    "payloadType": "json",
    "repeat": "",
    "crontab": "",
    "once": false,
    "x": 150,
    "y": 520,
    "wires": [
        [
            "81bfb514.a63348",
            "884f3eb9.e22be"
        ]
    ]
},
{
    "id": "e30f26ce.a084b8",
    "type": "change",
    "z": "7299298e.a9f058",
    "name": "invalid type",
    "rules": [
        {
            "t": "set",
            "p": "payload",
            "pt": "msg",
            "to": "Error! Unknown sensor type...",
            "tot": "str"
        }
    ],
    "action": "",
    "property": "",
    "from": "",
    "to": "",
    "reg": false,
    "x": 450,
    "y": 800,
    "wires": [
        [
            "cb13c651.0ef458"
        ]
    ]
},
{
    "id": "e02d2f38.842d8",
    "type": "ibmiot in",
    "z": "7299298e.a9f058",
    "authentication": "quickstart",
    "apiKey": "",
    "inputType": "evt",
    "deviceId": "3bd1c8df5ed2",
    "applicationId": "",
    "deviceType": "iotqs-sensor",
    "eventType": "+",
    "commandType": "",
    "format": "json",
    "name": "IBM IoT App In",
    "service": "quickstart",
    "allDevices": false,
    "allApplications": false,
    "allDeviceTypes": true,
    "allEvents": true,
    "allCommands": false,
    "allFormats": false,
    "x": 150,
    "y": 480,
    "wires": [
        [
            "884f3eb9.e22be",
            "81bfb514.a63348"
        ]
    ]
},
{
    "id": "59b72c5b.bc0fb4",
    "type": "swagger-doc",
    "z": "",
    "summary": "Retrieve last sensor reading",
    "description": "",
    "tags": "",
    "consumes": "",
    "produces": "",
    "parameters": [
        {
            "name": "type",
            "in": "path",
            "description": "Sensor type",
            "required": true,
            "type": "string"
        }
    ],
    "responses": {},
    "deprecated": false
}
]

请注意，我将 api url 更改为使用 /last/{type} 语法...其中 {type} 替换为您的 msg.payload.d 对象中的字段名称。