81 lines
4.2 KiB
Plaintext
81 lines
4.2 KiB
Plaintext
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<!-- { "title": "From InfluxDB to Twitter - daily temperature tweet" } -->
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<h1>#title#</h1>
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<p>
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This is my first attempt to build a tweetbot. I'm using node-red both as development and runtime environment. It comes with dedicated plugins for both InfluxDB and Twitter.
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</p>
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<p>
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The whole flow of the tweetbot is this:
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<img src="files/Screenshot_2019-01-04_08-28-39.png" width="1200"/>
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</p>
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<p>
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It starts with an inject node "Daily at noon" (<a href="files/Screenshot_2019-01-04_08-29-24.png" target="_blank">*</a>), with triggers the whole flow once a day at high noon.
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</p>
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<p>
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The four influx query nodes read data from the InfluxDB using the following queries, each one encapsulated in one influx query node:
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<pre><code class="SQL">
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select mean(pv) from measured where deviceid = 'Hedge' and kind = 'Temperature' and time > now() - 15m
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select mean(pv) from measured where deviceid = 'Hedge' and kind = 'Temperature' and time > now() - 24h
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select min(pv) from measured where deviceid = 'Hedge' and kind = 'Temperature' and time > now() - 24h
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select max(pv) from measured where deviceid = 'Hedge' and kind = 'Temperature' and time > now() - 24h
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</code></pre>
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See one of this node <a href="files/Screenshot_2019-01-04_08-29-47.png" target="_blank">here</a>.
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</p>
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<p>
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The data in the InfluxDB considered by these queries looks like this:
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<pre>
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> select * from measured where kind = 'Temperature' and deviceid = 'Hedge' limit 10
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name: measured
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time category deviceid kind pv qv sv tv
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---- -------- -------- ---- -- -- -- --
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2018-12-24T12:57:42.749065469Z Outdoor Hedge Temperature 5.029083728790283 -1
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2018-12-24T12:58:54.77913537Z Outdoor Hedge Temperature 5.020352363586426 -1
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2018-12-24T13:00:06.754460483Z Outdoor Hedge Temperature 5.032242298126221 -1
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2018-12-24T13:01:18.76525238Z Outdoor Hedge Temperature 5.024284362792969 -1
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2018-12-24T13:02:30.767286588Z Outdoor Hedge Temperature 5.016140937805176 -1
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2018-12-24T13:03:42.765550192Z Outdoor Hedge Temperature 5.0108466148376465 -1
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2018-12-24T13:04:54.774511705Z Outdoor Hedge Temperature 5.019856929779053 -1
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2018-12-24T13:06:05.772434549Z Outdoor Hedge Temperature 5.020042419433594 -1
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2018-12-24T13:07:16.759739681Z Outdoor Hedge Temperature 5.036855697631836 -1
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2018-12-24T13:08:27.757626686Z Outdoor Hedge Temperature 4.993878364562988 -1
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>
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</pre>
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<code>pv</code> has the temperature, <code>sv</code> has the battery voltage. In this case it is -1 since this particular thermometer is powered by a power supply from mains.
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</p>
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<p>
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In the following four change nodes (<a href="files/Screenshot_2019-01-04_08-30-06.png" target="_blank">*</a>) a dedicated topic for the messages from the influx query nodes will be set to merge them into a single key/value object in the following join node (<a href="files/Screenshot_2019-01-04_08-30-27.png" target="_blank">*</a>). This node will collect four messages and put them into a single object with the topic as key and the message as value.
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</p>
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<p>
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This object in turn is input for the function node "TextPreparator" (<a href="files/Screenshot_2019-01-04_08-30-48.png" target="_blank">*</a>) where the tweet is prepared using a small snippet of JavaScript code:
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<pre><code class="JavaScript">
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let output = ""
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output += `Die aktuelle Temperatur zuhause ist ${msg.payload.avg15min[0].mean.toFixed(1)}°C.\n`
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output += `Die Durchschnittstemperatur der letzten 24 Stunden war ${msg.payload.avg24h[0].mean.toFixed(1)}°C, `
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output += `die Tiefsttemperatur war ${msg.payload.min[0].min.toFixed(1)}°C um ${msg.payload.min[0].time.getHours()}:${msg.payload.min[0].time.getMinutes()} Uhr und `
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output += `die Höchsttemperatur war ${msg.payload.max[0].max.toFixed(1)}°C um ${msg.payload.max[0].time.getHours()}:${msg.payload.max[0].time.getMinutes()} Uhr.\n`
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output += "Powered by @NodeRED and @InfluxDB."
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msg.payload = output
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return msg;
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</code></pre>
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</p>
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<p>
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Finally this text will be sent to Twitter via the node "Tweet" (<a href="files/Screenshot_2019-01-04_08-31-06.png" target="_blank">*</a>). Done.
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</p>
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<p>
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<img src="files/Screenshot_2019-01-04_09-08-07.png"/>
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</p>
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