KEELSTONE_INSERT

Inserts a complete Excel workbook into the active Excel file. All worksheets from the provided .xlsx are appended at the end of the current workbook.

Payload

{
  type: 'KEELSTONE_INSERT';
  base64: string;    // Base64-encoded .xlsx file
  filename: string;  // Display name (not used for insertion, but saved to SF Files)
}

Field	Type	Description
type	'KEELSTONE_INSERT'	Discriminator — must be exactly this string
base64	string	The merged .xlsx encoded as base64
filename	string	Filename used when saving back to Salesforce Files

What Excel does

Excel.run((context) => {
  context.workbook.insertWorksheetsFromBase64(base64, {
    positionType: Excel.WorksheetPositionType.end
  });
  return context.sync();
});

All sheets in the provided workbook are inserted after the last existing sheet. The active sheet does not change.

Firing the event from your LWC

// myComponent.js
import { LightningElement } from 'lwc';

export default class MyComponent extends LightningElement {
  handleGenerateClick() {
    // ... build your base64 workbook ...
    const payload = {
      type: 'KEELSTONE_INSERT',
      base64: myBase64String,
      filename: 'My Report.xlsx'
    };

    // Fire both channels
    try { window.parent.postMessage(payload, '*'); } catch (e) {}
    document.dispatchEvent(new CustomEvent('keelstoneinsert', {
      detail: payload,
      bubbles: true
    }));
  }
}

Generating the base64 workbook

The recommended approach is to send your template and data to the Keelstone document generation endpoint and use the base64 from the response:

const response = await fetch('https://app.keelstone.dev/api/docs/generate', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({
    templateBase64: myTemplateBase64,
    data: { account: accountRecord, contacts: contactList }
  })
});
const { base64 } = await response.json();

See POST /api/docs/generate for full request/response details.

Example: complete LWC that generates and inserts

// reportGenerator.js
import { LightningElement, api, wire } from 'lwc';
import getTemplate from '@salesforce/apex/ExcelTemplateController.getTemplate';

export default class ReportGenerator extends LightningElement {
  @api templateId;
  @api mergeData;
  @api filename = 'Report.xlsx';

  isProcessing = false;
  error = null;

  connectedCallback() {
    this.generate();
  }

  async generate() {
    this.isProcessing = true;
    try {
      // 1. Fetch template from SF Files
      const templateBase64 = await getTemplate({ contentDocumentId: this.templateId });

      // 2. Merge via server
      const resp = await fetch('https://app.keelstone.dev/api/docs/generate', {
        method: 'POST',
        headers: { 'Content-Type': 'application/json' },
        body: JSON.stringify({
          templateBase64,
          data: JSON.parse(this.mergeData)
        })
      });
      if (!resp.ok) throw new Error(`Server error ${resp.status}`);
      const { base64 } = await resp.json();

      // 3. Send to Excel
      const payload = { type: 'KEELSTONE_INSERT', base64, filename: this.filename };
      try { window.parent.postMessage(payload, '*'); } catch (e) {}
      document.dispatchEvent(new CustomEvent('keelstoneinsert', { detail: payload, bubbles: true }));

    } catch (err) {
      this.error = err.message || 'An error occurred';
    } finally {
      this.isProcessing = false;
    }
  }
}