Often times, you might need to query the last value of one or more variables, across many devices. For example, when:

Doing a script to compute an aggregation for multiple devices (i.e. "Average of temperatures in the fifth floor", or "Count of machines where vibration is between a range").
Doing an ETL process to insert aggregated data into another system for further analysis.
Building a devices table or map view in your own web app.

In such cases, the Variables endpoint in our API v2.0 is a great option, as it allows for the use of filters. These can used to query specific variables from devices filtered by:

Individual device labels
Device group
Device type
Devices where a property value matches a criteria

See examples below.

Using individual device labels

Get only 3 fields from the Variable object, then filter results where label=<variable-label>, for the device labels given as a comma-separated list:

Method	URL
GET	`https://api.connectedsensors.com/api/v2.0/variables/?fields=device,label,lastValue&label=<variable-label>&device__label__in=<device-label-1>,<device-label-2>,<device-label-3>`

Response

{
  "count": 2,
  "next": null,
  "previous": null,
  "results": [
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6331c6aac590d801bbb446c4",
        "id": "6331c6aac590d801bbb446c4",
        "label": "07dbcccb4f3891d0df2d2cb0ae23fe37",
        "name": "City of Westminster",
        "createdAt": "2022-09-26T15:35:06.068177Z"
      },
      "lastValue": {
        "value": 1013,
        "timestamp": 1672962303000,
        "context": {},
        "created_at": 1672962305229
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6049251d0ff4c3276f76fcbc",
        "id": "6049251d0ff4c3276f76fcbc",
        "label": "aa05bbd986f208d399743dd8c14ae56c",
        "name": "Austin",
        "createdAt": "2021-03-10T19:59:25.461116Z"
      },
      "lastValue": {
        "value": 1022,
        "timestamp": 1672961758000,
        "context": {},
        "created_at": 1672961760088
      }
    }
  ]
}

Using device groups

Request

Method	URL
GET	`https://api.connectedsensors.com/api/v2.0/variables/?fields=device,label,lastValue&label=pressure&device__deviceGroup__label=weather`

Response

{
  "count": 7,
  "next": null,
  "previous": null,
  "results": [
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6331c6aac590d801bbb446c4",
        "id": "6331c6aac590d801bbb446c4",
        "label": "07dbcccb4f3891d0df2d2cb0ae23fe37",
        "name": "City of Westminster",
        "createdAt": "2022-09-26T15:35:06.068177Z"
      },
      "lastValue": {
        "value": 1013,
        "timestamp": 1672962303000,
        "context": {},
        "created_at": 1672962305229
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/62b202839649f3000a49048e",
        "id": "62b202839649f3000a49048e",
        "label": "8283a15646edd513cd4383f087910c2b",
        "name": "Menlo Park",
        "createdAt": "2022-06-21T17:40:19.300973Z"
      },
      "lastValue": {
        "value": 1014,
        "timestamp": 1672962262000,
        "context": {},
        "created_at": 1672962264201
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6272d0cf144554000a5b7932",
        "id": "6272d0cf144554000a5b7932",
        "label": "ef67f39f63a952c33f55e0135dd3939c",
        "name": "Barrancabermeja",
        "createdAt": "2022-05-04T19:15:27.263911Z"
      },
      "lastValue": {
        "value": 1005,
        "timestamp": 1651691749000,
        "context": {},
        "created_at": 1651691751082
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/604925a50ff4c32b89fb1c54",
        "id": "604925a50ff4c32b89fb1c54",
        "label": "862ea70b9c60f5c4ff4eff901723094b",
        "name": "Boston",
        "createdAt": "2021-03-10T20:01:41.878541Z"
      },
      "lastValue": {
        "value": 1016,
        "timestamp": 1657236448000,
        "context": {},
        "created_at": 1657236449496
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6049254a0ff4c3286361a10e",
        "id": "6049254a0ff4c3286361a10e",
        "label": "a6bc8da0e285470b50671f0b450e06c4",
        "name": "Fort Lauderdale",
        "createdAt": "2021-03-10T20:00:10.409204Z"
      },
      "lastValue": {
        "value": 1020,
        "timestamp": 1672961758000,
        "context": {},
        "created_at": 1672961759776
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6049251d0ff4c3276f76fcbc",
        "id": "6049251d0ff4c3276f76fcbc",
        "label": "aa05bbd986f208d399743dd8c14ae56c",
        "name": "Austin",
        "createdAt": "2021-03-10T19:59:25.461116Z"
      },
      "lastValue": {
        "value": 1022,
        "timestamp": 1672961758000,
        "context": {},
        "created_at": 1672961760088
      }
    },
    {
      "label": "pressure",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/604924ef4763e7161935af7b",
        "id": "604924ef4763e7161935af7b",
        "label": "31b24cede34944fbc43cb8432f956734",
        "name": "San Francisco",
        "createdAt": "2021-03-10T19:58:39.280681Z"
      },
      "lastValue": {
        "value": 1014,
        "timestamp": 1672961758000,
        "context": {},
        "created_at": 1672961759604
      }
    }
  ]
}

Using device types

Request

Method	URL
GET	`https://api.connectedsensors.com/api/v2.0/variables/?fields=device,label,lastValue&label=nh3&device__deviceType=air-pollution`

Response

{
  "count": 1,
  "next": null,
  "previous": null,
  "results": [
    {
      "label": "nh3",
      "device": {
        "url": "https://api.connectedsensors.com/api/v2.0/devices/6272d0b9390bf5000c80d74e",
        "id": "6272d0b9390bf5000c80d74e",
        "label": "weather-station-abc",
        "name": "Station ABC",
        "createdAt": "2022-05-04T19:15:05.154481Z"
      },
      "lastValue": {
        "value": 1.31,
        "timestamp": 1656522000000,
        "context": {},
        "created_at": 1656520678579
      }
    }
  ]
}