Files
twenty/packages/twenty-apps/examples/postcard
Paul RastoinandGitHub b8b115f4e3 FileStorageService Dedicated file and folder code flow + integrity check (#20831)
# Introduction

Next handling mimetype integrity check and checksum integrity check for
s3 storage type

Always expecting a trailing end slash when deleting a folder etc

## Application
Uninstalling an application now deletes all its related files

## File storage service
Making a distincton between folder path and file path

## Validation Pipeline

Every file operation in `FileStorageService.buildOnStoragePath` runs
through `validateResourcePath`, which chains three validators in order:

**1. `validateSafeRelativePath`** -- rejects path traversal attacks

| Input | Result | Error |
|---|---|---|
| `../../../etc/passwd` | Rejected | `Resource path must not contain
path traversal (..)` |
| `/etc/passwd` | Rejected | `Resource path must be relative, not
absolute` |
| `file\0.txt` | Rejected | `Resource path contains null bytes` |
| `..\\..\\etc\\passwd` | Rejected | `Resource path must not contain
backslashes` |
| _(empty)_ | Rejected | `Resource path must not be empty` |

**2. `validateFilenameIntegrity`** -- enforces safe characters, length
limits, extension required

| Input | Result | Error |
|---|---|---|
| `my folder/file.mjs` | Rejected | `A path segment contains invalid
characters...` |
| `Makefile` | Rejected | `Filename must have an extension` |
| `aaa...(256 chars).mjs` | Rejected | `A path segment exceeds the
maximum length of 255 characters` |
| `a/b/.../file.mjs` (1025+ chars) | Rejected | `Resource path exceeds
maximum length of 1024 characters` |
| `src/handlers/index.mjs` | Accepted | -- |
| `my-app/my_file.tsx` | Accepted | -- |
| `v1.0/module.config.mjs` | Accepted | -- |

Allowed characters per segment: `a-z`, `A-Z`, `0-9`, `.`, `-`, `_`

**3. `validateResourceExtension`** -- checks extension against the
`FileFolder` allowlist

| Input | FileFolder | Result | Error |
|---|---|---|---|
| `handler.js` | `BuiltLogicFunction` | Rejected | `Invalid file
extension. Allowed extensions: .mjs` |
| `card.tsx` | `BuiltFrontComponent` | Rejected | `Invalid file
extension. Allowed extensions: .mjs` |
| `script.js` | `PublicAsset` | Rejected | `Invalid file extension.
Allowed extensions: .png, .jpg, ...` |
| `index.mjs` | `BuiltLogicFunction` | Accepted | -- |
| `app.tsx` | `Source` | Accepted | -- |
| `photo.png` | `CorePicture` | Accepted | -- (unconfigured folder,
passes through) |

## Consumers

- **`FileStorageService`** -- calls `validateResourcePath`, throws
`FileStorageException` on failure (last-resort defense)
- **Resolver (`uploadApplicationFile`)** -- calls
`validateResourcePath`, throws `ApplicationException` on failure
(user-facing)
- **Flat validators** -- call `validateResourcePath`, push the error to
`validationResult.errors` (non-throwing, collects all errors)

All error messages are translated via Lingui `t` and returned in a
discriminated union `{ isValid: true } | { isValid: false, error: string
}`, letting each consumer decide how to handle failures.
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Postcard App — Twenty App Example

A rich example app showcasing all Twenty app entity types. Use this as a reference when building your own apps.

What's included

This app demonstrates every entity type available in the Twenty SDK:

Entity Files What it shows
Application src/application.config.ts App metadata, application variables, server variables
Objects src/objects/ Custom objects with inline fields, junction tables
Fields src/fields/ Standalone fields, relations (ONE_TO_MANY, MANY_TO_ONE), extending standard objects
Logic Functions src/logic-functions/ HTTP routes, database event triggers, cron schedules, tool functions, install hooks
Front Components src/components/ React components rendered inside Twenty's UI
Roles src/roles/ Permission roles with object and field-level access control
Views src/views/ Saved table views with column configuration
Navigation src/navigation-menu-items/ Sidebar links targeting views
Skills src/skills/ AI skill providing context to agents
Agents src/agents/ AI agent with a system prompt
Page Layouts src/page-layouts/ Custom record page with a front component widget

Getting started

# From this directory
yarn install
yarn twenty dev

Learn more