gatsby-node.js

const Sheets = require("node-sheets").default;
const createNodeHelpers = require("gatsby-node-helpers").default;
const camelCase = require("camelcase");

exports.sourceNodes = async ({ actions, createNodeId }, pluginOptions) => {
  const { createNode } = actions;
  const {
    spreadsheetId,
    spreadsheetName = "",
    typePrefix = "GoogleSpreadsheet",
    credentials,
    filterNode = () => true,
    mapNode = node => node
  } = pluginOptions;

  const { createNodeFactory } = createNodeHelpers({
    typePrefix
  });

  const gs = new Sheets(spreadsheetId);

  if (credentials) {
    await gs.authorizeJWT(credentials);
  }

  const promises = (await gs.getSheetsNames()).map(async sheetTitle => {
    const tables = await gs.tables(sheetTitle);
    const { rows } = tables;

    const buildNode = createNodeFactory(
      camelCase(`${spreadsheetName} ${sheetTitle}`)
    );
    rows
      .map(toNode)
      .filter(filterNode)
      .map(mapNode)
      .forEach((node, i) => {
        const hasProperties = Object.values(node).some(value => value !== null);
        if (hasProperties) {
          createNode({
            ...buildNode(node),
            id: createNodeId(
              `${typePrefix} ${spreadsheetName} ${sheetTitle} ${i}`
            )
          });
        }
      });
  });
  return Promise.all(promises);
};

function toNode(row) {
  return Object.entries(row).reduce((obj, [key, cell]) => {
    if (key === undefined || key === "undefined") {
      return obj;
    }

    // `node-sheets` adds default values for missing numbers and dates, by checking
    // for the precense of `stringValue` (the formatted value), we can ensure that
    // the value actually exists.
    const value =
      typeof cell === "object" && cell.stringValue !== undefined
        ? cell.value
        : null;
    obj[camelCase(key)] = value;

    return obj;
  }, {});
}