gon

**gon**

Short Forecast on Keppel DC Reit

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Graph Component

Finally we pass the series object to Graph component.

return (
  <div>
     <Graph
        height={props.height}
        width={props.width}
        series={series}
        timeRange={props.timeRange}
        showLines={true}
      />
  </div>
);

Here is everything in a single gist.

import React from 'react';
import { PanelProps, GraphSeriesXY, GraphSeriesValue } from '@grafana/data';
import { Graph } from '@grafana/ui';

export interface GraphPanelOptions {}

export const GraphPanel: React.FC<PanelProps<GraphPanelOptions>> = props => {
  let ser_ind: number = 0;
  const series: GraphSeriesXY[] = props.data.series.map(item => {
    const timeVals: Array<GraphSeriesValue> = item.fields[0].values.toArray();
    const yVals: Array<GraphSeriesValue> = item.fields[1].values.toArray();

    const data: GraphSeriesValue[][] = [];
    for (let i = 0; i < timeVals.length; i++) {
      data.push([timeVals[i], yVals[i]]);
    }

    const unixTimeRange = props.timeRange.to.unix() - props.timeRange.from.unix();
    const ser: GraphSeriesXY = {
      seriesIndex: ser_ind++,
      yAxis: { index: 0 },
      isVisible: true,
      timeField: props.data.series[0].fields[0],
      valueField: props.data.series[0].fields[1],
      timeStep: props.width / unixTimeRange,
      data: data,
      label: 'some label',
    };
    return ser;
  });

  return (
    <div>
      <Graph 
        height={props.height} 
        width={props.width} 
        series={series} 
        timeRange={props.timeRange} 
        showLines={true} 
      />
    </div>
  );
};

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Making a Graph Panel

Here is the definition of type of props defined in @grafana-ui for Graph component.

export interface GraphProps {
  ariaLabel?: string;
  children?: JSX.Element | JSX.Element[];
  series: GraphSeriesXY[];
  timeRange: TimeRange; // NOTE: we should aim to make `time` a property of the axis, not force it for all graphs
  timeZone?: TimeZone; // NOTE: we should aim to make `time` a property of the axis, not force it for all graphs
  showLines?: boolean;
  showPoints?: boolean;
  showBars?: boolean;
  width: number;
  height: number;
  isStacked?: boolean;
  lineWidth?: number;
  onHorizontalRegionSelected?: (from: number, to: number) => void;
}

series prop holds the data you want to render in your graph. Each line that you see on a normal Grafana chart is of type GraphSeriesXY. Each panel can render multiple lines for different metrics/variables and therefore series is an array of GraphSeriesXY. We can construct series prop from props.data.

All time-series data in Grafana is stored and used as an object of type DataFrame. It is kind of like data frames in data science if you are familiar with them (like pandas dataframes). props.data.series is of type DataFrame[], ie. you have a collection of time-series data stored as an array. Each item in this array corresponds to a single element in your GraphSeriesXY[] array. We have to therefore map object of type DataFrame to object of type GraphSeriesXY.

let ser_ind:number = 0;
const series:GraphSeriesXY[] = props.data.series.map(item => {
        const timeVals:Array<GraphSeriesValue> = item
                                                .fields[0]
                                                .values
                                                .toArray();
        const yVals:Array<GraphSeriesValue> =   item
                                                .fields[1]
                                                .values
                                                .toArray();

        const data:GraphSeriesValue[][] = [];
        for (let i = 0; i < timeVals.length; i++) {
            data.push([timeVals[i], yVals[i]]);
        }
        
        const unixTimeRange = (props.timeRange.to.unix() - props.timeRange.from.unix());
        const ser:GraphSeriesXY = {
            seriesIndex: ser_ind++,
            yAxis: {index:0},
            isVisible: true,
            timeField: props.data.series[0].fields[0],
            valueField: props.data.series[0].fields[1],
            timeStep: props.width / unixTimeRange,
            data: data,
        };
        return ser;
    });

Each item is of type DataFrame. The time-series data is stored in the fields array of item. Each field inside the fields array consists of data points for a single axis similar to column-oriented dbms.

We have two axis in our graphs, time (fields[0], x axis) and values (fields[1], y axis). We construct data of type GraphSeriesValue[][]. We create ser using data, fields and timeRange in unix values. From this transformation we get a series array which can be passed to Graph component. Make sure to give a distinct index to each item in series (ser_ind here). You can take a look at type GraphSeriesXY if you want to play around with other props like color, etc.

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Reference: https://medium.com/@hariom.2711/grafana-react-panel-plugins-545cb9afa42d

Plugin Basics

Your main panel should have props of type PanelProps<options>. You have to specify the type for options. options are basically used to enable the user to provide custom settings for your panel.

import React from 'react';
import { PanelProps } from '@grafana/data';

export interface GraphPanelOptions {

};

export const GraphPanel:React.FC<PanelProps<GraphPanelOptions>>
  = props => {
  return (
    <div></div>
  );
}

props will contain many attributes. Relevant ones for our GraphPanel are data, width, height, timeRange.

data attribute contains the whole of your time-series data. Each time-series contains two fields, the first one being your time points and the other one being the function you plot on y-axis. There will be multiple time-series which will come as different lines plotted on the same graph in your data attribute depending on your backend.

width, and height contain the actual width and height of the space allocated to your panel when it is rendered on Grafana.

timeRange is the time range selected by the user.

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Reference: https://corpglory.com/s/grafana-react-plugins/

PanelOptions

PanelOptions is passed as a PanelProps generic argument. Grafana will pass options from editor to your panel component as props.

export interface MyPanelOptions {
  someText: string;
}

export class MyPanel extends PureComponent<PanelProps<MyPanelOptions>> {
  render() {
    const { options } = this.props;

    return (
      <div>
        Text from editor: { options.someText }
      </div>
    );
  }
}

PanelEditor

PanelEditor is the separate component which represents "Visualization" tab and is used for configuring a panel plugin.

export class GaugePanelEditor extends PureComponent<PanelEditorProps<GaugeOptions>> {
  labelWidth = 6;

  render() {
    const { options, onChange } = this.props;

    return (
      <PanelOptionsGrid>
        <PanelOptionsGroup title="Some options">
          <Input
            className="gf-form-input width-5"
            type="text"
            value={options.someText}
            placeholder="Enter some text"
            onChange={event => {
              onChange({
                ...options
              });
            }}
          />
        </PanelOptionsGroup>
      </PanelOptionsGrid>
    );
  }
}