frappe-syntax-serverscripts

# Frappe Server Scripts — Complete Reference

Server Scripts are Python scripts managed via **Setup > Server Script** in the
Frappe/ERPNext UI. They run inside a **RestrictedPython sandbox**.

## CRITICAL: The Sandbox Rule

```
┌──────────────────────────────────────────────────────────────────┐
│  ALL import STATEMENTS ARE BLOCKED                               │
│                                                                  │
│  import json             → ImportError: __import__ not found     │
│  from datetime import *  → ImportError: __import__ not found     │
│  import frappe           → ImportError (even frappe itself!)     │
│                                                                  │
│  EVERYTHING you need is pre-loaded in the frappe namespace.      │
│  NEVER write an import line. ALWAYS use frappe.utils.*, etc.     │
└──────────────────────────────────────────────────────────────────┘
```

**ALWAYS** use the pre-loaded namespace instead of imports:

| Blocked import | Use instead |
|---|---|
| `import json` | `frappe.parse_json()` / `frappe.as_json()` |
| `from datetime import date` | `frappe.utils.today()` / `frappe.utils.now_datetime()` |
| `from frappe.utils import cint` | `frappe.utils.cint()` (already loaded) |
| `import requests` | `frappe.make_get_request()` / `frappe.make_post_request()` |
| `import re` | Not available — restructure logic without regex |
| `import os` / `import sys` | Not available — use a custom app instead |

## Enabling Server Scripts

```bash
# v14: enabled by default
# v15+: DISABLED by default — you MUST enable explicitly:
bench set-config -g server_script_enabled 1
# Or set server_script_enabled: true in site_config.json
```

**NEVER** expect Server Scripts to work on Frappe Cloud shared benches — they
require a private bench.

## Script Types

| Type | Trigger | Key Variable |
|---|---|---|
| **Document Event** | Document lifecycle (save, submit, cancel) | `doc` |
| **API** | HTTP request to `/api/method/{name}` | `frappe.form_dict` |
| **Scheduler Event** | Cron schedule | (none) |
| **Permission Query** | Document list filtering | `user`, `conditions` |

## Event Name Mapping (Document Events)

**CRITICAL**: The UI names differ from internal hook names:

| Server Script UI | Internal Hook | Fires When |
|---|---|---|
| Before Insert | `before_insert` | Before new doc saved to DB |
| After Insert | `after_insert` | After first DB insert |
| Before Validate | `before_validate` | Before framework validation |
| **Before Save** | **`validate`** | Before save (new + update) |
| After Save | `on_update` | After successful save |
| Before Submit | `before_submit` | Before submit (docstatus 0→1) |
| After Submit | `on_submit` | After submit completes |
| Before Cancel | `before_cancel` | Before cancel (docstatus 1→2) |
| After Cancel | `on_cancel` | After cancel completes |
| Before Delete | `on_trash` | Before permanent delete |
| After Delete | `after_delete` | After permanent delete |

**NEVER** confuse "Before Save" with `before_save` — the UI label "Before Save"
maps to the `validate` hook. The actual `before_save` hook runs AFTER `validate`.

## Decision Tree: Server Script vs Document Controller

```
Need custom Python logic for a DocType?
│
├─► Can you install a custom Frappe app?
│   ├─► YES: Use a Document Controller when you need:
│   │   • import statements (any Python library)
│   │   • File system access
│   │   • Complex class inheritance
│   │   • autoname / before_naming hooks
│   │   • Unit-testable code
│   │
│   └─► NO: Use a Server Script when:
│       • You only have UI access (no bench CLI)
│       • Logic is simple validation / field calculation
│       • You need a quick API endpoint
│       • You need dynamic permission filtering
│
└─► Is logic > 50 lines or needs external libraries?
    ├─► YES → Document Controller in a custom app
    └─► NO  → Server Script is fine
```

## Quick Reference: Available in Sandbox

### Pre-loaded Objects

```python
doc                         # Current document (Document Event only)
frappe                      # Core namespace — ALWAYS available
frappe.db                   # Database operations
frappe.utils                # Date, number, string utilities
frappe.session              # Current session (user, csrf_token)
frappe.form_dict            # Request parameters (API scripts)
frappe.response             # Response object (API scripts)
frappe.request              # Werkzeug request object
frappe.qb                   # Query Builder (v14+)
json                        # Python json module (pre-loaded)
```

### Core Methods

```python
# Documents
frappe.get_doc(doctype, name)           # Fetch document
frappe.new_doc(doctype)                 # Create new document
frappe.get_cached_doc(doctype, name)    # Cached fetch (read-only)
frappe.get_last_doc(doctype)            # Most recent document
frappe.get_mapped_doc(...)              # Map fields between DocTypes
frappe.delete_doc(doctype, name)        # Delete document
frappe.rename_doc(doctype, old, new)    # Rename document

# Querying
frappe.get_all(doctype, filters, fields, order_by, limit)   # No permission check
frappe.get_list(doctype, filters, fields, order_by, limit)  # With permission check
frappe.db.get_value(doctype, name, fieldname)
frappe.db.get_single_value(doctype, fieldname)
frappe.db.set_value(doctype, name, fieldname, value)
frappe.db.exists(doctype, name_or_filters)
frappe.db.count(doctype, filters)
frappe.db.sql(query, values, as_dict)   # ALWAYS parameterize!
frappe.db.escape(value)                 # SQL escape
frappe.db.commit()                      # ONLY in Scheduler scripts
frappe.db.rollback()                    # ONLY in Scheduler scripts

# Messaging
frappe.throw(msg, exc, title)           # Stop execution + show error
frappe.msgprint(msg, title, indicator)  # User notification
frappe.log_error(message, title)        # Error Log entry

# HTTP (yes, these work in sandbox!)
frappe.make_get_request(url, params