excelTemplate

Merges Salesforce data into an Excel template file and sends the result to the Excel taskpane. This is the component that produces the downloadable workbook.

Package: Keelstone-Samples
Component name: c:excelTemplate
Flow target: lightning__FlowScreen

Flow input properties

Property	Type	Required	Description
templateId	String	Yes	ContentDocumentId of the Excel template file in Salesforce Files
mergeData	String	Yes	JSON string of data to merge into the template (see Template Variables)
linkedEntityId	String	Yes	Record ID to attach the output file to (e.g., an Account Id)
filename	String	Yes	Output filename, e.g. "Acme Corp - Report.xlsx"

What it does

When the screen renders, the component runs automatically — no user action required:

1. Fetch template bytes   → ExcelTemplateController.getTemplate(templateId)
2. Merge data             → POST /api/docs/generate { templateBase64, data }
3. Signal Excel           → fires KEELSTONE_INSERT event (see Events Reference)
4. Save to SF Files       → ExcelTemplateController.saveDocument(base64, filename, linkedEntityId)

After step 3, the Excel taskpane receives the merged workbook and inserts it. After step 4, the file is saved to Salesforce Files and linked to the record you specified.

Status display

The component shows inline status as it works:

State	Display
Processing	Spinner + current step label
Done	Checkmark + "Document ready"
Error	Error message with detail

Events fired

See KEELSTONE_INSERT for the full event reference.

The component fires three signals for maximum compatibility with how Lightning Out renders the component:

// 1. postMessage — works when Lightning Out renders in an iframe
window.parent.postMessage(payload, '*');

// 2. Custom event on component — works for event listeners on the component itself
this.dispatchEvent(new CustomEvent('keelstoneinsert', {
  detail: payload,
  bubbles: true,
  composed: true
}));

// 3. Custom event on document — works when Lightning Out renders inline
document.dispatchEvent(new CustomEvent('keelstoneinsert', {
  detail: payload,
  bubbles: true
}));

All three carry the same payload:

{
  type: 'KEELSTONE_INSERT',
  base64: '<base64-encoded xlsx>',
  filename: 'Acme Corp - Report.xlsx'
}

Using in a flow

Place this component on the screen after accountSearch (or any component that produces mergeData):

<screen>
  <name>Doc_Gen_Screen</name>
  <fields>
    <componentType>c:excelTemplate</componentType>
    <inputParameters>
      <name>templateId</name>
      <value>
        <elementReference>myTemplateIdVariable</elementReference>
      </value>
    </inputParameters>
    <inputParameters>
      <name>mergeData</name>
      <value>
        <elementReference>mergeData</elementReference>
      </value>
    </inputParameters>
    <inputParameters>
      <name>linkedEntityId</name>
      <value>
        <elementReference>selectedAccountId</elementReference>
      </value>
    </inputParameters>
    <inputParameters>
      <name>filename</name>
      <value>
        <elementReference>outputFilename</elementReference>
      </value>
    </inputParameters>
  </fields>
</screen>

Finding the templateId

The templateId is the ContentDocumentId of an .xlsx file in Salesforce Files. The Keelstone Samples post-install handler creates a starter template in the "Keelstone Templates" content library automatically.

To find the ID:

ContentDocument doc = [
  SELECT Id FROM ContentDocument
  WHERE Title = 'Account Report Template'
  LIMIT 1
];
String templateId = doc.Id;

For production flows, store the ContentDocumentId in a Custom Metadata record or Flow variable so it can be configured without code changes.

Error handling

Scenario	Behavior
templateId not set or is placeholder	Error state: "Template not configured."
Template file not found in SF Files	Apex exception → error state
Server merge fails (5xx)	Error state with server message
saveDocument fails	Error state (Excel insert still succeeded)