@owlmeans/image-resource

The @owlmeans/image-resource package provides specialized image management functionality for OwlMeans Common Libraries, extending the core storage functionality with image-specific operations and validation schemas for handling images in object storage systems like S3.

Purpose

This package serves as an image-specific extension to the storage system, designed for:

• Image Storage Management: Specialized handling of image files in object storage
• Image Metadata: Enhanced metadata management specific to image files
• Validation Schemas: AJV schemas for image data validation
• Type Safety: TypeScript interfaces for image-related data structures
• Storage Integration: Seamless integration with OwlMeans storage infrastructure

Key Concepts

Image-specific Storage

Extends the basic file storage functionality with image-specific operations and metadata handling.

Type Extensions

Provides specialized TypeScript interfaces that extend the base storage types for image-specific use cases.

Schema Validation

Includes AJV schemas for validating image metadata and data structures.

Storage Abstraction

Builds upon the storage-common package to provide higher-level image management capabilities.

Installation

npm install @owlmeans/image-resource

API Reference

Types

ImageMeta

Metadata interface for stored images.

interface ImageMeta extends StoredFileMeta {
  // Extends base file metadata with image-specific properties
}

StoredImage

Interface for stored image files.

interface StoredImage extends StoredFile {
  // Extends base stored file interface for images
}

ImageData

Interface for image data with content.

interface ImageData extends StoredFileWithData {
  // Extends base file data interface for images
}

Validation Schemas

ImageMetaSchema

AJV schema for validating image metadata.

const ImageMetaSchema: JSONSchemaType<ImageMeta>

StoredImageSchema

AJV schema for validating stored image objects.

const StoredImageSchema: JSONSchemaType<StoredImage>

ImageDataSchema

AJV schema for validating image data with content.

const ImageDataSchema: JSONSchemaType<ImageData>

Usage Examples

Basic Image Validation

import { ImageMetaSchema, StoredImageSchema, ImageDataSchema } from '@owlmeans/image-resource'
import Ajv from 'ajv'

const ajv = new Ajv()

// Validate image metadata
const validateImageMeta = ajv.compile(ImageMetaSchema)
const isValidMeta = validateImageMeta(imageMetadata)

// Validate stored image
const validateStoredImage = ajv.compile(StoredImageSchema)
const isValidImage = validateStoredImage(imageObject)

// Validate image data
const validateImageData = ajv.compile(ImageDataSchema)
const isValidData = validateImageData(imageDataObject)

Integration with Storage Systems

import type { ImageMeta, StoredImage, ImageData } from '@owlmeans/image-resource'
import { ImageMetaSchema } from '@owlmeans/image-resource'

class ImageStorageService {
  async storeImage(file: File, metadata: Partial<ImageMeta>): Promise<StoredImage> {
    // Validate metadata
    const validateMeta = ajv.compile(ImageMetaSchema)
    if (!validateMeta(metadata)) {
      throw new Error('Invalid image metadata')
    }
    
    // Process and store image
    const storedImage: StoredImage = {
      id: generateId(),
      filename: file.name,
      contentType: file.type,
      size: file.size,
      ...metadata
    }
    
    return storedImage
  }
  
  async getImageData(imageId: string): Promise<ImageData> {
    // Retrieve image with data
    const imageData = await this.storage.getWithData(imageId)
    
    // Validate returned data
    const validateData = ajv.compile(ImageDataSchema)
    if (!validateData(imageData)) {
      throw new Error('Invalid image data format')
    }
    
    return imageData as ImageData
  }
}

Type-safe Image Operations

import type { ImageMeta, StoredImage } from '@owlmeans/image-resource'

interface ImageProcessor {
  processImage(image: StoredImage): Promise<StoredImage>
  getImageMetadata(imageId: string): Promise<ImageMeta>
  updateImageMetadata(imageId: string, metadata: Partial<ImageMeta>): Promise<void>
}

class BasicImageProcessor implements ImageProcessor {
  async processImage(image: StoredImage): Promise<StoredImage> {
    // Process the image (resize, compress, etc.)
    return {
      ...image,
      // Updated properties after processing
    }
  }
  
  async getImageMetadata(imageId: string): Promise<ImageMeta> {
    const metadata = await this.storage.getMetadata(imageId)
    return metadata as ImageMeta
  }
  
  async updateImageMetadata(imageId: string, metadata: Partial<ImageMeta>): Promise<void> {
    await this.storage.updateMetadata(imageId, metadata)
  }
}

Integration Patterns

Web Upload Handler

import type { ImageData } from '@owlmeans/image-resource'
import { ImageDataSchema } from '@owlmeans/image-resource'

async function handleImageUpload(file: File): Promise<ImageData> {
  // Create image data object
  const imageData: ImageData = {
    id: generateId(),
    filename: file.name,
    contentType: file.type,
    size: file.size,
    data: await file.arrayBuffer(),
    uploadedAt: new Date(),
    // Additional image-specific metadata
  }
  
  // Validate before processing
  const validate = ajv.compile(ImageDataSchema)
  if (!validate(imageData)) {
    throw new Error('Invalid image data')
  }
  
  return imageData
}

Storage Resource Integration

import { StorageResource } from '@owlmeans/storage-resource'
import type { StoredImage } from '@owlmeans/image-resource'

class ImageResource extends StorageResource<StoredImage> {
  constructor() {
    super({
      schema: StoredImageSchema,
      bucket: 'images',
      // Image-specific configuration
    })
  }
  
  async uploadImage(file: File, metadata?: Partial<ImageMeta>): Promise<StoredImage> {
    const imageData = await this.processFile(file)
    return await this.store({
      ...imageData,
      ...metadata
    })
  }
}

Best Practices

1. Validation: Always validate image data using provided schemas
2. Type Safety: Use TypeScript interfaces for compile-time safety
3. Metadata Management: Properly manage image-specific metadata
4. Integration: Leverage with storage-common and storage-resource packages
5. Error Handling: Implement proper error handling for validation failures

Dependencies

This package depends on:

• @owlmeans/storage-common - Core storage types and schemas
• ajv - JSON schema validation

Related Packages

• @owlmeans/storage-common - Core storage functionality
• @owlmeans/storage-resource - Storage resource management
• @owlmeans/resource - Base resource management