Joining a second grid

<link rel="stylesheet" href="https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.27.0/lattice-grid.min.css">

<div id="app"></div>

<script type="module">
  import React from 'https://esm.sh/react@18';
  import { createRoot } from 'https://esm.sh/react-dom@18/client';
  import { createGrid } from 'https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.27.0/lattice-grid.esm.min.js';
  import createLatticeGrid from 'https://cdn.jsdelivr.net/npm/@toclocoinc/lattice-grid@1.27.0/modules/react.esm.min.js';

  const LatticeGrid = createLatticeGrid({ React, createGrid });

  const USD = { style: 'currency', currency: 'USD', maximumFractionDigits: 0 };

  // The two sides: orders carry a customerId, and the tier lives on the customer.
  const customerColumns = [
    { field: 'id', title: 'ID' },
    { field: 'name', title: 'Customer' },
    { field: 'tier', title: 'Tier' },
  ];
  const orderColumns = [
    { field: 'customerId', title: 'Customer' },
    { field: 'region', title: 'Region', filter: { type: 'set' } },
    { field: 'amount', title: 'Value', type: 'number', format: USD, total: 'sum' },
  ];
  const byTierColumns = [
    { field: 'tier', title: 'Tier' },
    { field: 'revenue', title: 'Revenue', type: 'number', format: USD },
    { field: 'orders', title: 'Orders', type: 'number' },
  ];

  const customerRows = [/* [{ id: 'C0', name: 'Acme', tier: 'Enterprise' }, ...] */];
  const orderRows = [/* [{ id: 'O0', customerId: 'C0', region: 'EMEA', amount: 1240 }, ...] */];

  function App() {
    const ordersRef = React.useRef(null);
    const customersRef = React.useRef(null);
    const [derived, setDerived] = React.useState(null);

    // The join brings tier across from the customers grid onto each order,
    // matching customerId to id, then the group runs on that brought-across
    // field. Both sides are live instances, reached through their refs, so the
    // roll-up follows the filters on the orders grid.
    React.useEffect(() => {
      const orders = ordersRef.current && ordersRef.current.grid;
      const customers = customersRef.current && customersRef.current.grid;
      if (orders && customers) {
        setDerived({
          mode: 'derived', from: orders, follow: 'filtered', refresh: 'live',
          join: { with: customers, on: { left: 'customerId', right: 'id' }, select: ['tier'] },
          groupBy: 'tier',
          select: { revenue: { of: 'amount', fn: 'sum' }, orders: { fn: 'count' } },
          sort: [{ col: 'revenue', dir: 'desc' }],
        });
      }
    }, []);

    return (
      <>
        <div style={{ display: 'flex', gap: '16px' }}>
          <LatticeGrid
            ref={ordersRef}
            rowKey="id"
            toolPanel={{ side: 'left', panels: ['filters', 'columns'] }}
            columns={orderColumns}
            rows={orderRows}
            style={{ flex: 2, height: '300px' }}
          />
          <LatticeGrid
            ref={customersRef}
            rowKey="id"
            columns={customerColumns}
            rows={customerRows}
            style={{ flex: 1, height: '300px' }}
          />
        </div>
        {derived && (
          <LatticeGrid
            autoHeight
            source={derived}
            columns={byTierColumns}
            style={{ marginTop: '16px' }}
          />
        )}
      </>
    );
  }

  createRoot(document.getElementById('app')).render(<App />);
</script>