> ## Documentation Index
> Fetch the complete documentation index at: https://docs.twenty.com/llms.txt
> Use this file to discover all available pages before exploring further.

# 2. Generating documents

> One logic function, exposed as an AI tool and a workflow action.

Now the core: a [logic function](/developers/extend/apps/logic/logic-functions)
that loads a template and a record, fills the placeholders, and saves a new
document.

We'll write the business logic once as a **handler**, then expose it through
several triggers. This chapter wires up two of them — an **AI tool** and a
**workflow action**.

## The rendering helper

Keep pure logic in its own file so it's easy to unit-test. This flattens a record
into `{{dot.path}}` tokens and substitutes them.

```ts filename="src/logic-functions/utils/render-template.ts" theme={null}
const PLACEHOLDER_PATTERN = /\{\{\s*([\w.]+)\s*\}\}/g;

export const renderTemplate = (body: string, values: Record<string, string>) => {
  const missingTokens = new Set<string>();
  const content = body.replace(PLACEHOLDER_PATTERN, (_m, token: string) => {
    const value = values[token];
    if (value === undefined || value === '') { missingTokens.add(token); return ''; }
    return value;
  });
  return { content, missingTokens: [...missingTokens] };
};
```

<Tip>
  Because this file has no side effects, you can cover it with fast unit tests
  (`yarn test:unit`). See [Testing](/developers/extend/apps/operations/testing).
</Tip>

## The handler

The handler uses the generated [`CoreApiClient`](/developers/extend/apps/logic/logic-functions)
to read and write CRM data. It loads the template, loads the target record, fills
the body, and creates a `document`.

```ts filename="src/logic-functions/handlers/generate-document-handler.ts" theme={null}
import { CoreApiClient } from 'twenty-client-sdk/core';
import { loadRecordValues } from 'src/logic-functions/utils/load-record-values';
import { renderTemplate } from 'src/logic-functions/utils/render-template';

export const generateDocumentHandler = async (
  input: { templateId: string; recordId: string },
) => {
  const client = new CoreApiClient();

  // Use a filtered list query, not the singular lookup: the singular query
  // throws when nothing matches, which would become a 500 instead of a 404.
  const { documentTemplates } = await client.query({
    documentTemplates: {
      __args: { filter: { id: { eq: input.templateId } }, first: 1 },
      edges: { node: { id: true, name: true, body: true, target: true } },
    },
  });
  const documentTemplate = documentTemplates?.edges?.[0]?.node;
  if (!documentTemplate?.id) return { success: false, status: 404, message: 'Template not found.' };

  const record = await loadRecordValues(client, documentTemplate.target, input.recordId);
  if (!record.found) return { success: false, status: 404, message: 'Record not found.' };

  const { content, missingTokens } = renderTemplate(documentTemplate.body ?? '', record.values);

  const { createDocument } = await client.mutation({
    createDocument: {
      __args: { data: {
        name: `${documentTemplate.name} — ${record.displayName}`,
        content, status: 'GENERATED', templateId: documentTemplate.id,
      } },
      id: true, name: true,
    },
  });

  return { success: true, documentId: createDocument.id, content, missingTokens };
};
```

`loadRecordValues` runs a different query for a Person vs. a Company and flattens
the result — see
[`load-record-values.ts`](https://github.com/twentyhq/twenty/blob/main/packages/twenty-apps/examples/document-generator/src/logic-functions/utils/load-record-values.ts).

## Expose it as a tool and a workflow action

A single `defineLogicFunction` can carry several triggers. Here, `toolTriggerSettings`
makes it callable by AI agents, and `workflowActionTriggerSettings` turns it into a
step in the visual workflow builder. Both describe their input with a JSON schema.

```ts filename="src/logic-functions/generate-document.ts" theme={null}
import { defineLogicFunction } from 'twenty-sdk/define';
import { jsonSchemaToInputSchema } from 'twenty-sdk/logic-function';
import { GENERATE_DOCUMENT_LOGIC_FUNCTION_UNIVERSAL_IDENTIFIER } from 'src/constants/universal-identifiers';
import { generateDocumentHandler } from 'src/logic-functions/handlers/generate-document-handler';
import { generateDocumentInputSchema } from 'src/logic-functions/schemas/generate-document-input.schema';

export default defineLogicFunction({
  universalIdentifier: GENERATE_DOCUMENT_LOGIC_FUNCTION_UNIVERSAL_IDENTIFIER,
  name: 'generate-document',
  description: 'Generate a document from a template and a CRM record.',
  timeoutSeconds: 30,
  toolTriggerSettings: {
    inputSchema: generateDocumentInputSchema,
  },
  workflowActionTriggerSettings: {
    label: 'Generate Document',
    icon: 'IconFileText',
    inputSchema: jsonSchemaToInputSchema(generateDocumentInputSchema),
    outputSchema: [{ type: 'object', properties: {
      success: { type: 'boolean' }, documentId: { type: 'string' },
    } }],
  },
  handler: generateDocumentHandler,
});
```

The input schema is a plain JSON schema describing `templateId` and `recordId` —
see [`generate-document-input.schema.ts`](https://github.com/twentyhq/twenty/blob/main/packages/twenty-apps/examples/document-generator/src/logic-functions/schemas/generate-document-input.schema.ts).

## Grant it access

Logic functions run as the app's role. It needs to read templates and records
and create documents, so allow that in `src/roles/default-role.ts`:

```ts theme={null}
export default defineApplicationRole({
  universalIdentifier: DEFAULT_ROLE_UNIVERSAL_IDENTIFIER,
  label: 'Document Generator default role',
  canReadAllObjectRecords: true,
  canUpdateAllObjectRecords: true,
  canAccessAllTools: true,
  canBeAssignedToAgents: true,
  permissionFlagUniversalIdentifiers: [SystemPermissionFlag.UPLOAD_FILE],
});
```

`UPLOAD_FILE` lets the function upload the generated PDF in the next section.
See [Roles](/developers/extend/apps/config/roles) for finer-grained permissions.

## Attach a real PDF file

A rendered text field is useful, but users want a real document. Let's generate a
**PDF** and store it on the record as a downloadable file.

First, give the `document` object a `FILES` field to hold the PDF. Apps upload
into their **own** files fields, so this field is what routes the upload:

```ts filename="src/objects/document.object.ts" theme={null}
{
  universalIdentifier: DOCUMENT_FILE_FIELD_UNIVERSAL_IDENTIFIER,
  type: FieldType.FILES,
  name: 'file',
  label: 'File',
  icon: 'IconFileTypePdf',
  universalSettings: { maxNumberOfValues: 1 },
}
```

Now render that PDF. An app is a real Node project, so you can add any npm
package you need and import it like anywhere else. We use **[pdf-lib](https://pdf-lib.js.org/)**
to draw the PDF and **[marked](https://marked.js.org/)** to parse the Markdown
body — the CLI installs them into the function's runtime for you:

```bash filename="Terminal" theme={null}
yarn add pdf-lib marked
```

The full helper is
[`generate-document-pdf.ts`](https://github.com/twentyhq/twenty/blob/main/packages/twenty-apps/examples/document-generator/src/logic-functions/utils/generate-document-pdf.ts).
It parses the Markdown into tokens with `marked.lexer`, then lays them out with
pdf-lib: real headings, **bold**/*italic* runs, bullet and numbered lists,
blockquotes and rules — a polished, multi-page A4 rendering of the template
itself, rather than a wall of text.

<Frame caption="The generated PDF: real typography and Markdown formatting, rendering the template body.">
  <img src="https://mintcdn.com/twenty/sqJBeTZq-W-RDBPU/images/docs/developers/extends/apps/document-generator/07b-generated-pdf.png?fit=max&auto=format&n=sqJBeTZq-W-RDBPU&q=85&s=ab29f3ed244aa424e850abe73f8c082d" alt="A polished, marketable generated PDF" width="1286" height="1200" data-path="images/docs/developers/extends/apps/document-generator/07b-generated-pdf.png" />
</Frame>

<Note>
  pdf-lib's built-in fonts use WinAnsi encoding, so Western-European accents render
  out of the box; the helper maps smart quotes and dashes and drops characters it
  can't encode. Rendering non-Latin scripts (Chinese, Arabic, Cyrillic) would mean
  embedding a Unicode font.
</Note>

Then upload it and store the reference on the record. `uploadFile` routes bytes
to your app-owned files field; the returned `id` is what you save:

```ts filename="src/logic-functions/handlers/generate-document-handler.ts" theme={null}
import { MetadataApiClient } from 'twenty-client-sdk/metadata';
import { generateDocumentPdf } from 'src/logic-functions/utils/generate-document-pdf';

const documentName = `${documentTemplate.name} — ${record.displayName}`;
const bytes = await generateDocumentPdf(documentName, content);
const fileName = 'proposal.pdf';

const uploaded = await new MetadataApiClient().uploadFile(
  Buffer.from(bytes),
  fileName,
  'application/pdf',
  DOCUMENT_FILE_FIELD_UNIVERSAL_IDENTIFIER,
);

await client.mutation({
  updateDocument: {
    __args: {
      id: documentId,
      data: { file: [{ fileId: uploaded.id, label: fileName }] },
    },
    id: true,
  },
});
```

The generated document now carries a downloadable PDF:

<Frame caption="The generated PDF, stored on the document's File field.">
  <img src="https://mintcdn.com/twenty/sqJBeTZq-W-RDBPU/images/docs/developers/extends/apps/document-generator/08-document-with-pdf.png?fit=max&auto=format&n=sqJBeTZq-W-RDBPU&q=85&s=afbc1091577e93482b71dcc0d73af110" alt="A document record with a generated PDF file" width="2880" height="1800" data-path="images/docs/developers/extends/apps/document-generator/08-document-with-pdf.png" />
</Frame>

<Note>
  `uploadFile` only targets **app-owned** files fields (so uploads always require an
  app that owns the field, plus the `UPLOAD_FILE` role flag). That's why the PDF
  lands on the record's own `file` field — the same pattern the
  [call-recorder app](https://github.com/twentyhq/twenty/tree/main/packages/twenty-apps/public/call-recorder)
  uses for recordings.
</Note>

**After this step:** each generated document has a real, downloadable PDF. But
nothing can *call* the generator from the UI yet — for that we need an HTTP route.

<Card title="Next: HTTP routes →" icon="globe" href="/developers/extend/apps/tutorials/document-generator/http-routes">
  Serve the function over HTTP and render documents as web pages.
</Card>