​
1. Add a new chart type

Add a new type in mage_ai/data_preparation/models/widget/constants.py: 
class ChartType(str, Enum):
    # ...
    PIE_CHART = 'pie_chart'
Add a new type in mage_ai/frontend/interfaces/ChartBlockType.ts: 
export enum ChartTypeEnum {
  // ...
  PIE_CHART = 'pie_chart',
}
export const CHART_TYPES = [
  // ...
  ChartTypeEnum.PIE_CHART,
];

​
2. Define the configuration options for the chart

In the file mage_ai/frontend/components/ChartBlock/constants.ts, add a list of options for the user to configure their chart with: 
export const CONFIGURATIONS_BY_CHART_TYPE = {
  [ChartTypeEnum.PIE_CHART]: [
    {
      label: () => 'variable name of values',
      monospace: true,
      uuid: 'super_cool_uuid',
    },
  ],
};
Also, add the new variable name to the following constant in the file mage_ai/frontend/interfaces/ChartBlockType.ts,: 
export const VARIABLE_NAMES = [
  'super_cool_uuid',
];
If 1 or more of the configuration options is for a variable name that can be defined in the chart block’s code and referenced at presentation time, then you must add the following in the file mage_ai/data_preparation/models/widget/constants.py: 
VARIABLE_NAMES_BY_CHART_TYPE = {
    ChartType.PIE_CHART: [
        'super_cool_uuid',
    ],
}

​
Add default settings to the configuration

When a user selects a chart type, you can set default values for these options. In the file mage_ai/frontend/interfaces/ChartBlockType.ts, add the following: 
export const DEFAULT_SETTINGS_BY_CHART_TYPE = {
  [ChartTypeEnum.PIE_CHART]: {
    configuration: () => ({
      [VARIABLE_NAME_X]: 'x',
    }),
    content: ({
      upstream_blocks: upstreamBlocks = [],
    }: BlockType) => {
      const uuid = upstreamBlocks[0];
      return `x = ${uuid}[${uuid}.columns[0]]`;
    },
  },
};

​
Add helpful information about the variable type that the chart expects

Each chart requires 1 or more input values. The chart knows how to access those input values by referencing a variable name that the user inputs into the configuration options. Each variable can be of a certain type; array/list of strings, integers, etc. To help the user know how to set the variables properly, add the following information into the file mage_ai/frontend/components/ChartBlock/constants.ts: 
export const VARIABLE_INFO_BY_CHART_TYPE = {
  [ChartTypeEnum.PIE_CHART]: {
    [VARIABLE_NAME_X]: (): string => 'must be a list of booleans, dates, integers, floats, or strings.',
  },
};

​
3. Define post processing logic for chart data

In the file mage_ai/data_preparation/models/widget/__init__.py, add additional logic for parsing the input values from the variables defined in the chart block’s code. The output of this method is provided to the front-end React components for rendering. 
class Widget(Block):
    def post_process_variables(self, variables):
        if ChartType.PIE_CHART == self.chart_type:
            variables = {}
        return variables

​
4. Create React component for rendering chart

In the file mage_ai/frontend/components/ChartBlock/ChartController.tsx, import your React component for your new chart and render it. For example: 
function ChartController({
  block,
  data,
  width,
}: ChartControllerProps) {
  const {
    configuration,
  } = block;
  const chartType = configuration?.chart_type;
  if (ChartTypeEnum.PIE_CHART === chartType) {
    return <PieChart />;
  }
}