graphql2chartjs - Instant realtime charts using GraphQL

graphql2chartjs reshapes your GraphQL data as per the ChartJS API. This makes it easy to query a GraphQL API and render the output as a ChartJS chart.

For example, if you're using Postgres and Hasura, this is what using graphql2chartjs looks like:

Demos & sandbox

We've set up a GraphQL server with continuously changing data, so that you can try graphql2chartjs out easily.

The demo above cover the following types of charts: basic, multiple datasets, mixed chart-types, realtime chart with live data, realtime time-series

Usage with Hasura

Hasura gives you an instant realtime GraphQL API on an existing Postgres database. You can create views to capture analytics and aggregations on your database and instantly turn them into charts.

Watch this video below to see a demo/tutorial of using Hasura with an existing Postgres database, creating views and building charts.

Example usage with react, apollo and react-chartjs-2

import {Query} from 'react-apollo';
import gql from 'graphql-tag';
import graphql2chartjs from 'graphql2chartjs';
import {Bar} from 'react-chartjs-2';

const Chart = () => (
  <Query
    query={gql`
      query {
        Articles: articleStats {
          label: title
          data: num_likes
        }
      }`}
    }>
    {({data} => {
      if (data) {
        const g2c = new graphql2chartjs(data, 'bar');
        return (<Bar data={g2c.data} />);
      }
      return null;
    }
  </Query>
);

Mapping GraphQL queries to ChartJS charts

Different types of charts need different structures in their datasets.

For example a bar chart dataset needs labels and data associated for each label; the ChartJS API refers to this as label and data. Once you alias fields in your graphql query to label and data, and pass the response through graphql2chartjs, your dataset is ready to be used by bar chart in chartjs.

Bar / Line / Doughnut / Pie / Radar / Polar Area / Area

Charts of this type need 2 data inputs, label and data.

query {
  ArticleLikes : articles {
    label: title
    data: likes
  }
}

Scatter / Bubble

Charts of this type need 2 data inputs: data_x, data_y (and data_r for bubble).

query {
  ArticleLikesVsComments : articles {
    data_x: num_likes
    data_y: num_comments
  }
}

Time series (line / bar)

Charts of this type need 2 data inputs, data_x or data_t and data_y. Note that there is no label.

query {
  StockPrices : stockprice {
    data_t: created
    data_y: price
  }
}

graphql2chartjs usage

graphql2chartjs works in 3 steps:

1. Initialise graphql2chartjs: const g2c = new graphql2chartjs()
2. Add data from your graphql response: g2c.add(graphqlResponse.data, 'line')
3. Set your chart data to the data properly of the graphql2chartjs instance: g2c.data

Step 1: Initialiase with data: new graphql2chartjs()

Option 1: Initialise with data and chart type

graphql2chartjs(data, chartType)

const g2c = new graphql2chartjs(data, 'bar');

• data: This is your GraphQL response. This data should have fields label, data etc. as per the GraphQL querying described above.
• chartType: This is a string that represents valid values of what your chart type is. Valid values include 'line', 'bar', 'radar', 'doughnut', 'pie', 'polarArea', 'bubble', 'scatter'.

Notes:

• This is the simplest way of using graphql2chartjs
• If you have multiple datasets, all of the datasets will be rendered automatically as the same type of chart
• To customise the UI options of the rendered chart like colors or to create a mixed type chart (one dataset is rendered as a line chart, another as a bar chart) use the next initialisation method instead of this one.

Option 2: Initialise with data and a transform function

graphql2chartjs(data, transform)

The transformation function can add chartjs dataset props or even modify the record data:

const g2c = new graphql2chartjs(data, (datasetName, dataPoint) => {
  return {
    chartType: 'bar',
    backgroundColor: 'yellow'
  };
});

• transform(datasetName, dataPoint): This function defined by you can take the name of the dataset and the data record that comes from the GraphQL response and returns an object that can should have the chartType key and optionally other keys that specify other dataset properties.
  • The object returned by this function should look like the following:

  {
    chartType: 'line', // Or 'line', 'bar', 'radar', 'doughnut', 'pie', 'polarArea', 'bubble', 'scatter'
    <other keys as per the dataset properties per chart. Refer to the link below>
  }

  • chartType: This should be a string value, one of: 'line', 'bar', 'radar', 'doughnut', 'pie', 'polarArea', 'bubble', 'scatter'
  • Other keys in this object should be dataset properties. These properties are slightly different for different chart types.
    • Line chart: https://www.chartjs.org/docs/latest/charts/line.html#dataset-properties
    • Bar chart: https://www.chartjs.org/docs/latest/charts/bar.html#dataset-properties
    • Radar chart: https://www.chartjs.org/docs/latest/charts/radar.html#dataset-properties
    • Doughnut & Pie: https://www.chartjs.org/docs/latest/charts/doughnut.html#dataset-properties
    • Polar: https://www.chartjs.org/docs/latest/charts/polar.html#dataset-properties
    • Bubble: https://www.chartjs.org/docs/latest/charts/bubble.html#dataset-properties
    • Scatter: https://www.chartjs.org/docs/latest/charts/scatter.html#dataset-properties

Step 2: Now create your chart with data - g2c.data

g2c.data gives you access to the latest ChartJS data that can be passed to your chart.

1. Javascript

var myChart = new Chart(ctx, { data: g2c.data });

2. react-chartjs-2

<Bar data={g2c.data} />

Step 3: (optional) Incrementally add data for your chart

g2c.add()

Once you've initialised a graphql2chartjs object, you can use the add function to add data for the first time or incrementally:

await data = runQuery(..);

// Add for a chart type
g2c.add(data, 'line');

// Add with a transformation function to change UI props for the new data added or udpated
g2c.add(data, (datasetName, dataPoint) => {
  chartType: 'line',
  pointBackgroundColor: 'yellow'
});

Installation

Via npm

npm install --save graphql2chartjs

Use in a script tag

<script src="https://storage.googleapis.com/graphql-engine-cdn.hasura.io/tools/graphql2chartjs/index.js" type="application/javascript"></script>

Reforming the data

reform()

You can reform the existing data in your graphql2chartjs instance using the reform function that takes a reformer function as an argument. This reformer function is run over every datapoint in every dataset. For instance, to scale the x and y coordinates, you would do something like:

g2c.reform((datasetName, dataPoint) => {
  // scale the x, y coordinates
  return {
    data_x: scalingFactor(dataPoint.data_x),
    data_y: scalingFactor(dataPoint.data_y)
  }
})