# Possibility to delete the collected values in a fully configurable charts in a dashboard template node

**URL:** <https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666>\
**Category:** General\
**Created:** [10 March 2022 16:46 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666 "2022-03-10T16:46:45Z")\
**Posts on this page:** 6\
**Page:** 1

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**Author:** ![Jackcat](https://avatars.discourse-cdn.com/v4/letter/j/b3f665/32.png) [@Jackcat](https://discourse.nodered.org/u/Jackcat)\
**Post date:** [10 March 2022 16:46 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/1 "2022-03-10T16:46:45Z")

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Hello Node-Red Community,

I have a problem that I have been struggling with for a few days now and would like your advice.

I wanted to create a chart with X and Y axis labels in the dashboard. After ruling out the possibility of using a normal "chart node", I came across colinl's post "Using Chart.js to show fully configurable charts in a dashboard template node" ([https://flows.nodered.org/flow/c3dc75c47323a2754f5285225bce64b5](https://flows.nodered.org/flow/c3dc75c47323a2754f5285225bce64b5)) in the Node-Red forum.

With the help of a "dropdown-node" I could read in values from different sources, under the topic "Sin".

My problem is the following:

When I change the selection in the "dropdown", the values of the new source are shown before the values of the old sources.

Unfortunately I have no experience with Java and only little experience with Node-Red.

Is there any way to insert a function in the code provided in the forum or perhaps change a value dynamically with a flow.object so that all the old values are removed in the diagram and only the new values are shown?

Thank you.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [10 March 2022 17:17 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/2 "2022-03-10T17:17:29Z")

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This demo should get you started...

> [@Problem with X/Y graph with ui\_graph](https://discourse.nodered.org/t/problem-with-x-y-graph-with-ui-graph/46713/8):
>
> Here is a scatter demo using chart.js... [4CJBilIHJz] [{"id":"acbdb34e9e6d9720","type":"change","z":"553814a2.1248ec","name":"random x/y","rules":[{"t":"set","p":"payload","pt":"msg","to":"(\t $minimum := 1;\t $maximum := 100;\t $x := $round(($random() \* ($maximum-$minimum)) + $minimum, 0);\t $y := $round(($random() \* ($maximum-$minimum)) + $minimum, 0);\t {\t \"x\": $x,\t \"y\": $y\t }\t)","tot":"jsonata"}],"action":"","property":"","from":"","to":"","reg":fals…

PS: AFAIK, there is no reason the built in chart cannot be used

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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:** [10 March 2022 22:30 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/3 "2022-03-10T22:30:34Z")

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> [@Jackcat](#):
>
> I came across colinl's post "Using Chart.js to show fully configurable charts in a dashboard template node"

Wow, that was nearly 6 years ago! I am amazed it is that long ago. I am pretty sure the current dashboard chart node will do anything that flow did.

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**Author:** ![Jackcat](https://avatars.discourse-cdn.com/v4/letter/j/b3f665/32.png) [@Jackcat](https://discourse.nodered.org/u/Jackcat)\
**Post date:** [11 March 2022 08:40 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/4 "2022-03-11T08:40:27Z")

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Thank you for the feedback,

using the "normal" "chart-node" does allow you to delete all displayed values by sending "", but not to display axis labels. I know I could also just display the axis label above the chart as the chart label, but that doesn't look scientific enough.  
I have therefore resorted to the code from "colinl". Since this enables axis labelling with time information on the X-axis.  
Unfortunately I can't see through the code to find out on my own what I have to insert in what place in order to also delete all values with a "", as with the "normal" "chart-node".

Thanks for the help.

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**Author:** ![Steve-Mcl](https://sea2.discourse-cdn.com/flex026/user_avatar/discourse.nodered.org/steve-mcl/32/4826_2.png) [@Steve-Mcl](https://discourse.nodered.org/u/Steve-Mcl)\
**Post date:** [11 March 2022 08:51 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/5 "2022-03-11T08:51:33Z")

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> [@Jackcat](#):
>
> Unfortunately I can't see through the code to find out on my own what I have to insert in what place in order to also delete all values with a "", as with the "normal" "chart-node"

The demo i posted a link to does that when the "CLEAR" button is pressed. In case you cannot see the wood for the trees...

1. the CLEAR button sends an empty array `[]` in `msg.payload` with a `msg.topic` of `set`
2. In the template named `scatter`, the `msg` is seen to have a topic of `set` so then uses the payload (which if you remember is an empty array `[]`) to set the chart data.

```auto
        if(msg.topic == "set") {
          myChart.data.datasets[0].data = [...msg.payload];
          myChart.update();
        }

```

Or to simplify, it could have been a separate "clear" action e.g...

```auto
        if(msg.topic == "clear") {
          myChart.data.datasets[0].data = [];
          myChart.update();
        }

```

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<div class="post-metadata">

**Author:** ![system](https://us1.discourse-cdn.com/flex026/uploads/nodered/original/1X/d073cd938eafa2e558d7c2cd59003b3ef4963033.png) [@system](https://discourse.nodered.org/u/system)\
**Post date:** [25 March 2022 08:52 UTC](https://discourse.nodered.org/t/possibility-to-delete-the-collected-values-in-a-fully-configurable-charts-in-a-dashboard-template-node/59666/6 "2022-03-25T08:52:32Z")

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