Create custom PDF documents from templates with Gemini & Google Drive
*This workflow contains community nodes that are only compatible with the self-hosted version of n8n.*
## 1 — What Does It Do / Which Problem Does It Solve?
This workflow turns Google Docs-based contract & form templates into **ready-to-sign PDFs in minutes**—all from a single chat flow.
- **Automates repetitive document creation.** Instead of copying a rental, sales, or NDA template and filling it by hand every time, the bot asks for the required values and fills them in.
- **Eliminates human error.** It lists every mandatory field so nothing is missed, and removes unnecessary clauses via conditional blocks.
- **Speeds up approvals.** The final draft arrives as a direct PDF link—one click to send for signing.
- **One template → unlimited variations.** Every new template you drop in Drive is auto-listed with **zero workflow edits—**it scales effortlessly.
- **100 % no-code.** Runs on n8n + Google Apps Script—no extra backend, self-hosted or cloud.
---
## 2 — How It Works (Detailed Flow)
1. 📝 **Template Discovery**
📂 The **TemplateList** node scans the Drive folder you specify via the `?mode=meta` endpoint and returns an `id / title / desc` list. The bot shows this list in chat.
2. 🎯 **Selection & Metadata Fetch**
The user types a template name.
🔍 **GetMetaData** opens the chosen Doc, extracts `META_JSON`, placeholders, and conditional blocks, then lists mandatory & optional fields.
3. 🗣 **Data-Collection Loop**
- The bot asks for every **placeholder** value.
- For each **conditional block** it asks 🟢 **Yes** / 🔴 **No**.
Answers are accumulated in a `data` JSON object.
4. ✅ **Final Confirmation**
The bot summarizes the inputs → when the user clicks **Confirm**, the *DocProcess* sub-workflow starts.
5. ⚙️ **DocProcess Sub-Workflow**
| 🔧 Step | Node | Task |
| --- | --- | --- |
| 1 | **User Choice Match Check** | Verifies name–ID match; throws if wrong |
| 2 | **GetMetaData (renew)** | Gets the latest placeholder list |
| 3 | **Validate JSON Format** | Checks for missing / unknown fields |
| 4 | **CopyTemplate** | Copies the Doc via Drive API |
| 5 | **FillDocument** | Apps Script fills placeholders & removes blocks |
| 6 | **Generate PDF Link** | Builds an `export?format=pdf` URL |
6. 📎 **Delivery**
The master agent sends **🔗 Download PDF** & **✏️ Open Google Doc** links.
7. 🚫 **Error Paths**
- `status:"ERROR", missing:[…]` → bot lists missing fields and re-asks.
- `unknown:[…]` → template list is outdated; rerun *TemplateList*.
- Any Apps Script error → the returned `message` is shown verbatim in chat.
---
## 3 — 🚀 Setup Steps (Full Checklist)
> Goal: Get a flawless PDF on the first run.
>
>
> Mentally **tick** the ☑️ in front of every line as you go.
>
### ☁️ A. Google Drive Preparation
| Step | Do This | Watch Out For |
| --- | --- | --- |
| 1 | Create a `Templates/` folder → put every template Doc inside | Exactly **one** folder; **no** sub-folders |
| 2 | Placeholders in every Doc are **`{{UPPER_CASE}}`** | No Turkish chars or spaces |
| 3 | Wrap optional clauses with **`[[BLOCK_NAME:START]]…[[BLOCK_NAME:END]]`** | The `START` tag must have a **blank line above** |
| 4 | Add a `META_JSON` block at the very end | Script deletes it automatically after fill |
| 5 | Right-click Doc > **Details ▸ Description** = 1-line human description | Shown by the bot in the list |
| 6 | Create a second `Generated/` folder (for copies) | Keeps Drive tidy |
> 🔑 Folder ID (long alphanumerical) = <TEMPLATE_PARENT_ID>
>
>
> We’ll paste this into the TemplateList node next.
>
[Simple sample template → Template Link](https://www.notion.so/Simple-sample-template-Template-Link-22b3f8a1e57f8070beacd034ba6f557f?pvs=21)
---
### 🛠 B. Import the Workflow into n8n
```bash
Settings ▸ Import Workflow ▸ DocAgent.json
```
If nodes look **Broken** afterwards → no community-node problem; you only need to select credentials.
---
### 📑 C. Customize the TemplateList Node
1. Open **Template List** node ⚙️ → replace
`'%3CYOUR_PARENT_ID%3E' in parents`
with the real **folder ID** in the **URL**.
2. Right-click node > **Execute Node**.
3. Copy the entire JSON response.
4. In the editor paste it into:
- **DocAgent** → *System Prompt* (top)
- **User Choice Match Check** → *System Prompt* (top)
Save.
> ⚠️ Why manual? Caching the list saves LLM tokens. Whenever you add a template, rerun the node and update the prompts.
>
---
### 🔗 D. Deploy the Apps Script
| Step | Screen | Note |
| --- | --- | --- |
| 1 | Open Gist files **GetMetaData.gs** + **FillDocument.gs** → *File ▸ Make a copy* | Both files may live in one project |
| 2 | *Project Settings* > enable **Google Docs API** ✔️ & **Google Drive API** ✔️ | Otherwise you’ll see 403 errors |
| 3 | *Deploy ▸ New deployment ▸ Web app* | |
| • Execute as | **Me** | |
| • Who has access | **Anyone** | |
| 4 | On the consent screen allow scopes:• `…/auth/documents`• `…/auth/drive` | Click **Advanced › Go** if Google warns |
| 5 | Copy the **Web App URL** (e.g. `https://script.google.com/macros/s/ABC123/exec`) | If this URL changes, update n8n |
[Apps Script source code → Notion Link](https://www.notion.so/Apps-Script-source-code-Notion-Link-22b3f8a1e57f8015a280d90de16c031f?pvs=21)
---
### 🔧 E. Wire the Script URL in n8n
| Node | Field | Action |
| --- | --- | --- |
| **GetMetaData** | *URL* | `<WEB_APP_URL>?mode=meta&id={{ $json["id"] }}` |
| **FillDocument** | *URL* | `<WEB_APP_URL>` |
> 💡 Prefer using an .env file? Add GAS_WEBAPP_URL=… and reference it as {{ $env.GAS_WEBAPP_URL }}.
>
---
### 🔐 F. Add Credentials
- **Google Drive OAuth2** → *Drive API (v3) Full Access*
- **Google Docs OAuth2** → same account
- **LLM key** (OpenAI / Gemini)
- (Optional) **Postgres Chat Memory** credential for the corresponding node
---
### 🧪 G. First Run (Smoke Test)
1. Switch the workflow **Active**.
2. In the chat panel type `/start`.
3. Bot lists templates → pick one.
4. Fill mandatory fields, optionally toggle blocks → **Confirm**.
5. **🔗 Download PDF** link appears → ☑️ setup complete.
---
### ❌ H. Common Errors & Fixes
| 🆘 Error | Likely Cause | Remedy |
| --- | --- | --- |
| `403: Apps Script permission denied` | Web app access set to *User* | Redeploy as **Anyone**, re-authorize scopes |
| `placeholder validation failed` | Missing required field | Provide the listed values → rerun DocProcess |
| `unknown placeholders: …` | Template vs. agent mismatch | Check placeholder spelling (UPPER_CASE ASCII) |
| `Template ID not found` | Prompt list is old | Rerun **TemplateList** → update both prompts |
| `Cannot find META_JSON` | No meta block / wrong tag | Add `[[META_JSON_START]] … [[META_JSON_END]]`, retry |
---
### ✅ Final Checklist
- [ ] Drive folder structure & template rules ready
- [ ] Workflow imported, folder ID set in node
- [ ] TemplateList output pasted into both prompts
- [ ] Apps Script deployed, URL set in nodes
- [ ] OAuth credentials & LLM key configured
- [ ] `/start` test passes, PDF link received
---
## 🙋♂️ Need Help with Customizations?
Reach out for consulting & support on LinkedIn: [**Özgür Karateke**](https://www.notion.so/DocAgent-Documentation-22b3f8a1e57f8085baa9c70cdead41cd?source=copy_link)
[Full Documentation → Notion](https://www.notion.so/Simple-sample-template-Template-Link-22b3f8a1e57f8070beacd034ba6f557f?pvs=21)
[Simple sample template → Template Link](https://www.notion.so/Simple-sample-template-Template-Link-22b3f8a1e57f8070beacd034ba6f557f?pvs=21)
[Apps Script source code → Notion Link](https://www.notion.so/Apps-Script-source-code-Notion-Link-22b3f8a1e57f8015a280d90de16c031f?pvs=21)
