# How to get data for a variable time

**URL:** <https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016>\
**Category:** General\
**Created:** [26 August 2020 05:13 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016 "2020-08-26T05:13:30Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![akhtar321h](https://avatars.discourse-cdn.com/v4/letter/a/9de0a6/32.png) [@akhtar321h](https://discourse.nodered.org/u/akhtar321h)\
**Post date:** [26 August 2020 05:13 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/1 "2020-08-26T05:13:31Z")

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Hello Everyone,

I am generating some random data through random node continuously. and i am storing that data in a buffer.  
I want to access data from buffer for a variable time period, like last 5 min data or last 1 hour data. Please give me any solution for this. or any other possible way to do this.

Thank you

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<div class="post-metadata">

**Author:** ![akhtar321h](https://avatars.discourse-cdn.com/v4/letter/a/9de0a6/32.png) [@akhtar321h](https://discourse.nodered.org/u/akhtar321h)\
**Post date:** [26 August 2020 05:14 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/2 "2020-08-26T05:14:51Z")

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Here is my flow...

````auto
[{"id":"8e9492af.b9b2f","type":"subflow","name":"FIFO","info":"# FIFO\n## First in First Out subflow\nThis flow receives a series of msg.payloads and builds a queue using FIFO (First in First out) method. The LIFO size is configurabe through subflow enviroment variables.\n\n### Input\n`msg.topic == put`\nWill add the `msg.payload` to the end of the array. Everytime a new item is received the second output sends the complete queue.\n\n`msg.topic == get`\nWill remove the first item of the stack and will send it in the first output\n\n`msg.topic == list`\nSends the complete list on the second output.\n\n### Output 1\nThe first item on the top of the stack. It is sent only when `msg.topic == get`.\n\n### Output 2\nThe complete queue in Array format. It is sent everytime a new item is added, removed or when `msg.topic == list`\n\n### Status\nAlways show the queue size.\n\n### Enviroment Variables\n`Buffer_Size` defines the size of the queue. If a new item arrives and the queue is full, the oldest item will be removed.","category":"","in":[{"x":140,"y":120,"wires":[{"id":"cb121310.2edaa"}]}],"out":[{"x":720,"y":60,"wires":[{"id":"e9e46f98.25b71","port":0}]},{"x":900,"y":100,"wires":[{"id":"90e47b30.5284b8","port":0}]}],"env":[{"name":"Buffer_Size","type":"num","value":"6"}],"color":"#DDAA99","icon":"font-awesome/fa-ellipsis-v","status":{"x":1040,"y":140,"wires":[{"id":"1756dadd.968eb5","port":0}]}},{"id":"cb121310.2edaa","type":"switch","z":"8e9492af.b9b2f","name":"Topic","property":"topic","propertyType":"msg","rules":[{"t":"eq","v":"get","vt":"str"},{"t":"eq","v":"put","vt":"str"},{"t":"eq","v":"list","vt":"str"}],"checkall":"true","repair":false,"outputs":3,"x":270,"y":120,"wires":[["e9e46f98.25b71"],["eef1a399.8dc"],["90e47b30.5284b8"]]},{"id":"eef1a399.8dc","type":"function","z":"8e9492af.b9b2f","name":"put","func":"var queue = flow.get(\"queue\")\n\n\nif (!Array.isArray(queue)){\n queue = [];\n}else if ( queue.length >= env.get(\"Buffer_Size\") ){\n queue.pop(1);\n}\n\nqueue.unshift(msg.payload);\n\nflow.set(\"queue\", queue);\nmsg.payload = queue;\n\nreturn msg;","outputs":1,"noerr":0,"x":550,"y":100,"wires":[[]]},{"id":"e9e46f98.25b71","type":"function","z":"8e9492af.b9b2f","name":"get","func":"var queue = flow.get(\"queue\")\nvar item;\n\nif (!Array.isArray(queue)){\n queue = [];\n}else{\n item = queue.pop(1);\n}\n\n\nflow.set(\"queue\", queue)\nmsg.payload = item;\n\nreturn msg;","outputs":1,"noerr":0,"x":550,"y":60,"wires":[[]]},{"id":"90e47b30.5284b8","type":"change","z":"8e9492af.b9b2f","name":"list","rules":[{"t":"set","p":"payload","pt":"msg","to":"queue","tot":"flow"}],"action":"","property":"","from":"","to":"","reg":false,"x":750,"y":140,"wires":[["1756dadd.968eb5"]]},{"id":"1756dadd.968eb5","type":"change","z":"8e9492af.b9b2f","name":"Count","rules":[{"t":"set","p":"payload","pt":"msg","to":"$count(msg.payload)\t","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":false,"x":930,"y":140,"wires":[[]]},{"id":"1701644b.039a1c","type":"inject","z":"40696538.c8266c","name":"","topic":"","payload":"","payloadType":"date","repeat":"5","crontab":"","once":false,"onceDelay":0.1,"x":110,"y":100,"wires":[["1f0ffc91.b09ca3"]]},{"id":"1f0ffc91.b09ca3","type":"random","z":"40696538.c8266c","name":"","low":"1","high":"10","inte":"true","property":"payload","x":260,"y":100,"wires":[["f208ff83.d1a04"]]},{"id":"2ce6ce4a.a3be52","type":"subflow:8e9492af.b9b2f","z":"40696538.c8266c","name":"","env":[{"name":"Buffer_Size","value":"100","type":"num"}],"x":570,"y":100,"wires":[["4abf6729.57b3e8"],["5df798d7.465e38","88693d37.c9889","4e3654f8.e7785c"]]},{"id":"f208ff83.d1a04","type":"function","z":"40696538.c8266c","name":"Log_msg","func":"var res=msg.payload;\nmsg={\n \"topic\":\"put\",\n \"payload\":res\n}\nreturn msg;","outputs":1,"noerr":0,"x":420,"y":100,"wires":[["2ce6ce4a.a3be52"]]},{"id":"4abf6729.57b3e8","type":"debug","z":"40696538.c8266c","name":"","active":false,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":730,"y":80,"wires":[]},{"id":"7893fd80.cfdec4","type":"inject","z":"40696538.c8266c","name":"","topic":"","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":280,"y":320,"wires":[["4e3654f8.e7785c"]]},{"id":"4e3654f8.e7785c","type":"function","z":"40696538.c8266c","name":"Reset_Buffer","func":"var arr=msg.payload;\nfor(let i=0;i<arr.length;i++)\n{\n msg={\n \"topic\":\"get\"\n }\n node.send(msg);\n}\nreturn;\n ","outputs":1,"noerr":0,"x":570,"y":280,"wires":[["2ce6ce4a.a3be52"]]},{"id":"5df798d7.465e38","type":"debug","z":"40696538.c8266c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":730,"y":140,"wires":[]},{"id":"88693d37.c9889","type":"function","z":"40696538.c8266c","name":"Calculation","func":"var arr=msg.payload;\n//var arr = [3, 6, 2, 56, 32, 5, 89, 32];\nvar largest1 = arr[0];\n\nfor (let i = 0; i < arr.length; i++) {\n if (largest1 < arr[i] ) {\n largest1 = arr[i];\n }\n}\n\nmsg.payload=\n{\n \"Topic\": \"Max_Temp\",\n \"Temp\": largest1\n}\nreturn msg;","outputs":1,"noerr":0,"x":750,"y":220,"wires":[["114b798a.9a2186"]]},{"id":"114b798a.9a2186","type":"debug","z":"40696538.c8266c","name":"","active":true,"tosidebar":true,"console":false,"tostatus":false,"complete":"false","x":710,"y":340,"wires":[]},{"id":"545a639b.9c7cfc","type":"inject","z":"40696538.c8266c","name":"","topic":"list","payload":"","payloadType":"date","repeat":"","crontab":"","once":false,"onceDelay":0.1,"x":250,"y":200,"wires":[["2ce6ce4a.a3be52"]]}]```
````

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<div class="post-metadata">

**Author:** ![Bobo](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/bobo/32/8401_2.png) [@Bobo](https://discourse.nodered.org/u/Bobo)\
**Post date:** [26 August 2020 06:32 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/3 "2020-08-26T06:32:05Z")

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There are many ways you could approach this. Have you looked at some of the timer nodes available to see which might suit? [https://flows.nodered.org/search?term=timer](https://flows.nodered.org/search?term=timer)

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<div class="post-metadata">

**Author:** ![ArneR](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/arner/32/95658_2.png) [@ArneR](https://discourse.nodered.org/u/ArneR)\
**Post date:** [26 August 2020 06:54 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/4 "2020-08-26T06:54:24Z")

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Hey

Does your data keep coming in every 5 seconds?

If this is not the case, you will also have to provide the time of the data somewhere, I think. Otherwise you can never look back over a desired period. Another option is to have your calculation performed on x number of data, for example for the last 10 measurements.

I think the following is easy to get working:

> **Code:**
>
> ```auto
> var largest1 = arr[0];
> var number = msg.number;
> 
> if (number === 0){
> number = arr.length
> }
> 
> for (let i = 0; i < number; i++) {
> if (largest1 < arr[i] ) {
> largest1 = arr[i];
> }
> }
> 
> msg.payload=
> {
> "Topic": "Max_Temp",
> "Temp": largest1,
> "Number": number
> }
> return msg;
> 
> ```

- inject a number in your calculation.
- The number represents your last x number of measurements.  
If you inject 0, take all values in the buffer.  
Don't forget that your array must also enter: join node.

I am not a programmer, there will certainly be easier / better ways but with some try and error it will be fine 😅

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<div class="post-metadata">

**Author:** ![UnborN](https://avatars.discourse-cdn.com/v4/letter/u/4491bb/32.png) [@UnborN](https://discourse.nodered.org/u/UnborN)\
**Post date:** [26 August 2020 09:28 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/5 "2020-08-26T09:28:55Z")

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Hi,

In your subflow in the 'put' function you have this :  
`var queue = flow.get("queue")`  
you try to get flow queue and it seems that it is not even defined on initialization of the main flow.

and also because you are using a **subflow**.. from the [documents about flow context](https://nodered.org/docs/user-guide/context)

> _Note_ : for nodes in a subflow, the `flow` context is shared by those nodes and not the flow the subflow is on. From Node-RED 0.20, the nodes inside a subflow can access the context of the parent flow by prepending `$parent.` to the context key. For example:
> 
> var colour = flow.get("$parent.colour");

Regarding storing data in context "continuously" and then retrieving it by going back even 1 hour .. i don't know .. maybe others can advice on how much data you can store in context.  
What is the max time you want to store ?

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<div class="post-metadata">

**Author:** ![akhtar321h](https://avatars.discourse-cdn.com/v4/letter/a/9de0a6/32.png) [@akhtar321h](https://discourse.nodered.org/u/akhtar321h)\
**Post date:** [26 August 2020 14:10 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/6 "2020-08-26T14:10:10Z")

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Maximum time is 12 hour.

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<div class="post-metadata">

**Author:** ![UnborN](https://avatars.discourse-cdn.com/v4/letter/u/4491bb/32.png) [@UnborN](https://discourse.nodered.org/u/UnborN)\
**Post date:** [26 August 2020 16:41 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/7 "2020-08-26T16:41:09Z")

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( 12 hours x 60 minutes x 60 seconds ) / ( every 5 seconds ) = 8640 records in context ?

as @ArneR mentioned, i guess you will need to store the datetime as well 2020-08-26 07:30:00  
so you can later use array.filter to filter out based on the range .. or maybe an advanced jsonata  
[Array Filter video](https://youtu.be/rRgD1yVwIvE?t=706)

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**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [25 October 2020 16:41 UTC](https://discourse.nodered.org/t/how-to-get-data-for-a-variable-time/32016/8 "2020-10-25T16:41:10Z")

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