Disk Storage

Disk Storage is a storage service based on the local file system, providing high-speed file read/write capabilities and direct file path access. It is suitable for small applications, development environments, and internal system deployments with high data security requirements. Disk Storage supports file upload, download, delete, preview, and thumbnail generation functions, with built-in MIME type recognition and error handling mechanisms.

The Disk Storage element has a hierarchical structure of Meta (storages.Meta) → Type (storages.DiskType) → Instance. Developers can quickly create disk storage instance elements through JitAI's visual development tools.

Of course, developers can also create their own Type elements or modify the official storages.DiskType element provided by JitAI in their own App to implement their own encapsulation.

Quick Start

Creating Instance Elements

Directory Structure

Recommended Directory Structure

storages/
└── MyDiskStorage/                    # Storage element name, customizable
    ├── e.json                        # Element definition file
    └── MyDiskStorage.json           # Business configuration file

e.json File

Element Definition Configuration

{
  "title": "My Disk Storage",
  "type": "storages.DiskType",
  "backendBundleEntry": "."
}

Business Configuration File

MyDiskStorage.json

{
  "directory": "appData/storages/MyDiskStorage"
}

Usage Example

Basic Usage Example

# Get disk storage instance
storage = app.getElement("storages.MyDiskStorage")

# Upload file
with open("test.txt", "rb") as file:
    result = storage.uploadByFile("test.txt", file.read(), "text/plain")
    print(result['url'])  # Returns file access URL

# Download file
response = storage.download("test.txt")

# Delete file
storage.delete("test.txt")

Element Configuration

e.json Configuration

Configuration Item	Type	Required	Description
title	string	Yes	Storage element display name
type	string	Yes	Fixed value: "storages.DiskType"
backendBundleEntry	string	Yes	Fixed value: "."

Business Configuration File Configuration

The business configuration file name must be the same as the element name and contains the following configuration items:

Configuration Item	Type	Required	Description
directory	string	Yes	Storage directory path. Can be relative path (relative to application directory) or absolute path

Path Description:

• Relative path: appData/storages/MyStorage → Application Directory/appData/storages/MyStorage
• Absolute path: /data/files → Use absolute path directly

Methods

uploadByFile

Upload file to disk storage.

Parameter Details

Parameter Name	Type	Corresponding Native Type	Required	Description
name	Stext	str	Yes	File name, including extension
data	-	bytes	Yes	File binary data
contentType	Stext	str	No	MIME type, defaults to "application/octet-stream"

Return Value

Returns a dictionary containing file access URL:

{
    "url": "http://domain/storages/services/StorageSvc/preview?file=filename.txt"
}

Usage Example

File Upload Example

storage = app.getElement("storages.MyDiskStorage")

# Upload text file
with open("document.txt", "rb") as file:
    result = storage.uploadByFile("document.txt", file.read(), "text/plain")
    
# Upload image file
with open("image.jpg", "rb") as file:
    result = storage.uploadByFile("image.jpg", file.read(), "image/jpeg")

download

Download specified file.

Parameter Details

Parameter Name	Type	Corresponding Native Type	Required	Description
file	Stext	str	Yes	File name to download

Return Value

Returns Flask Response object containing file content and correct MIME type headers.

Usage Example

File Download Example

storage = app.getElement("storages.MyDiskStorage")

# Download file
response = storage.download("document.txt")
# Response will automatically set correct Content-Type and download headers

delete

Delete specified file.

Parameter Details

Parameter Name	Type	Corresponding Native Type	Required	Description
name	Stext	str	Yes	File name to delete

Usage Example

File Delete Example

storage = app.getElement("storages.MyDiskStorage")

# Delete file
storage.delete("document.txt")

preview

Preview specified file, supports direct display in browser.

Parameter Details

Parameter Name	Type	Corresponding Native Type	Required	Description
file	Stext	str	Yes	File name to preview

Return Value

Returns Flask Response object set to inline display mode.

Usage Example

File Preview Example

storage = app.getElement("storages.MyDiskStorage")

# Preview file
response = storage.preview("image.jpg")
# Image will be displayed directly in browser

previewThumbnail

Generate and return file thumbnail, mainly for image files.

Parameter Details

Parameter Name	Type	Corresponding Native Type	Required	Description
name	Stext	str	Yes	Image file name
width	Numeric	int	No	Thumbnail width, defaults to 120 pixels
height	Numeric	int	No	Thumbnail height, defaults to 120 pixels

Return Value

Returns Flask Response object of thumbnail. If thumbnail doesn't exist, it will be automatically generated and cached.

Usage Example

Thumbnail Generation Example

storage = app.getElement("storages.MyDiskStorage")

# Generate default size thumbnail
thumbnail = storage.previewThumbnail("photo.jpg")

# Generate specified size thumbnail
thumbnail = storage.previewThumbnail("photo.jpg", 200, 150)

Attributes

rootDir

Read-only attribute, returns the absolute path of the storage root directory.

name

Read-only attribute, returns the fullName of the storage element.

Advanced Features

Automatic Directory Creation

Disk Storage automatically creates required directory structure when uploading files:

Nested Directory File Upload

storage = app.getElement("storages.MyDiskStorage")

# Upload to subdirectory, directory will be automatically created
with open("doc.pdf", "rb") as file:
    result = storage.uploadByFile("documents/2024/doc.pdf", file.read())

Automatic MIME Type Recognition

The system has built-in rich MIME type mapping, supporting automatic recognition of hundreds of file formats:

MIME Type Processing

storage = app.getElement("storages.MyDiskStorage")

# System will automatically set correct MIME type based on file extension
storage.uploadByFile("video.mp4", video_data)  # Automatically recognized as video/mp4
storage.uploadByFile("document.pdf", pdf_data)  # Automatically recognized as application/pdf

Thumbnail Caching Mechanism

Generated thumbnails are saved on disk to avoid repeated generation:

Thumbnail Caching Strategy

storage = app.getElement("storages.MyDiskStorage")

# First call will generate thumbnail file: image_120_120.jpg
thumbnail1 = storage.previewThumbnail("image.jpg", 120, 120)

# Subsequent calls directly return already generated thumbnail
thumbnail2 = storage.previewThumbnail("image.jpg", 120, 120)

Permission Error Handling

When directory permissions are insufficient, the system throws friendly error messages:

Permission Error Handling

try:
    storage.uploadByFile("test.txt", b"content")
except Exception as e:
    # Will display relative path instead of complete system path
    print(f"Permission error: {e}")