# Clean a chart with a button

**URL:** <https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185>\
**Category:** Dashboard\
**Created:** [29 June 2018 11:50 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185 "2018-06-29T11:50:53Z")\
**Posts on this page:** 9\
**Page:** 1

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**Author:** ![gabrieldicieri](https://avatars.discourse-cdn.com/v4/letter/g/9dc877/32.png) [@gabrieldicieri](https://discourse.nodered.org/u/gabrieldicieri)\
**Post date:** [29 June 2018 11:50 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/1 "2018-06-29T11:50:53Z")

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I need to reset a chart with a button in node-RED and i didnt know where to start. The buttn has to clear all the data in de chart, any ideas that how i can do that?

Thanks Gabriel

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**Author:** ![Colin](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/colin/32/17040_2.png) [@Colin](https://discourse.nodered.org/u/Colin)\
**Post date:** [29 June 2018 12:20 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/2 "2018-06-29T12:20:17Z")

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As it says in the Info tab for the node “Inputting a msg.payload containing a blank array [] will clear the chart”. So you need to make your button send a message back to node red and on receipt of that send a message to the chart with a payload consisting of an empty array.

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**Author:** ![gabrieldicieri](https://avatars.discourse-cdn.com/v4/letter/g/9dc877/32.png) [@gabrieldicieri](https://discourse.nodered.org/u/gabrieldicieri)\
**Post date:** [29 June 2018 12:36 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/3 "2018-06-29T12:36:02Z")

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im starting now with node-red, whats the syntax of an blank array to node-red? thanks for your help and patience

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**Author:** ![davidcgu](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@davidcgu](https://discourse.nodered.org/u/davidcgu)\
**Post date:** [29 June 2018 12:44 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/4 "2018-06-29T12:44:06Z")

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on the msy.payload of the button leave payload on blank like this

![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/2d777763e8f97d6b8f693cc1004c3810740a1bb4.png)

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**Author:** ![gabrieldicieri](https://avatars.discourse-cdn.com/v4/letter/g/9dc877/32.png) [@gabrieldicieri](https://discourse.nodered.org/u/gabrieldicieri)\
**Post date:** [29 June 2018 12:49 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/5 "2018-06-29T12:49:46Z")

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not worked ☹

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**Author:** ![davidcgu](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@davidcgu](https://discourse.nodered.org/u/davidcgu)\
**Post date:** [29 June 2018 12:52 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/6 "2018-06-29T12:52:53Z")

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![image](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/fe4fb1b4fae9f92fd54183bab8bc17cceedc5114.png)

sorry

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**Author:** ![knolleary](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/knolleary/32/3_2.png) [@knolleary](https://discourse.nodered.org/u/knolleary)\
**Post date:** [29 June 2018 12:54 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/7 "2018-06-29T12:54:34Z")

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@davidcgu no, that injects a blank String, not a blank array - it will not work.

@gabrieldicieri To create an Inject node that injects a blank array, select the JSON type and type in `[]`:

 ![Local_Node-RED](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/138c76653bb55e733443d209ac0a0d7e1e423d8c.png)

That gives you a node you can click on the button within the editor to inject the message with a blank array as the payload.

Or you could use a Function node with the code:

```auto
msg.payload = [];
return msg;

```

Or you could use a Change node, in a similar fashion to the Inject node:

 ![Local_Node-RED](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/b338a2b1b042b91152276f8c74960e2453fabb71.png)

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**Author:** ![davidcgu](https://avatars.discourse-cdn.com/v4/letter/d/e8c25b/32.png) [@davidcgu](https://discourse.nodered.org/u/davidcgu)\
**Post date:** [29 June 2018 12:56 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/8 "2018-06-29T12:56:58Z")

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I completely messed up, right, thanks again Knolleary and sorry for the confusing information I should have checked how I have it done on my flows before answering so happily

Regards.

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**Author:** ![gabrieldicieri](https://avatars.discourse-cdn.com/v4/letter/g/9dc877/32.png) [@gabrieldicieri](https://discourse.nodered.org/u/gabrieldicieri)\
**Post date:** [29 June 2018 13:02 UTC](https://discourse.nodered.org/t/clean-a-chart-with-a-button/1185/9 "2018-06-29T13:02:46Z")

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Problem Solved, you are the guy, thank you so much!