Reddit DevOps

content types, including articles and products
- Allow adding new content types
- Support comments

### Non-functional requirements

- Performance
- Availability
- Elasticity

### Why Document Store is Better Here

As we have no critical transaction like in the previous example but are only interested in performance, availability and elasticity, document stores are a great choice. Considering that various content types is a requirement, our life is easier with document stores as they are schema-less.

### Data Model

```json
// Article document
{
"id": "article123",
"type": "article",
"title": "Understanding NoSQL",
"author": {
"id": "user456",
"name": "Jane Smith",
"email": "[email protected]"
},
"content": "Lorem ipsum dolor sit amet...",
"tags": ["database", "nosql", "tutorial"],
"published": true,
"publishedDate": "2025-05-01T10:30:00Z",
"comments": [
{
"id": "comment789",
"userId": "user101",
"userName": "Bob Johnson",
"text": "Great article!",
"timestamp": "2025-05-02T14:20:00Z",
"replies": [
{
"id": "reply456",
"userId": "user456",
"userName": "Jane Smith",
"text": "Thanks Bob!",
"timestamp": "2025-05-02T15:45:00Z"
}
]
}
],
"metadata": {
"viewCount": 1250,
"likeCount": 42,
"featuredImage": "/images/nosql-header.jpg",
"estimatedReadTime": 8
}
}

// Product document (completely different structure)
{
"id": "product789",
"type": "product",
"name": "Premium Ergonomic Chair",
"price": 299.99,
"categories": ["furniture", "office", "ergonomic"],
"variants": [
{
"color": "black",
"sku": "EC-BLK-001",
"inStock": 23
},
{
"color": "gray",
"sku": "EC-GRY-001",
"inStock": 14
}
],
"specifications": {
"weight": "15kg",
"dimensions": "65x70x120cm",
"material": "Mesh and aluminum"
}
}
```

### Spring Boot Implementation with MongoDB

```java
@Document(collection = "content")
public class ContentItem {
@Id
private String id;
private String type;
private Map<String, Object> data;

// Common fields can be explicit
private boolean published;
private Date createdAt;
private Date updatedAt;

// The rest can be dynamic
@DBRef(lazy = true)
private User author;

private List<Comment> comments;

// Basic getters and setters
}

// MongoDB Repository
public interface ContentRepository extends MongoRepository<ContentItem, String> {
List<ContentItem> findByType(String type);
List<ContentItem> findByTypeAndPublishedTrue(String type);
List<ContentItem> findByData_TagsContaining(String tag);
}

// Service for content management
@Service
public class ContentService {
private final ContentRepository contentRepository;

@Autowired
public ContentService(ContentRepository contentRepository) {
this.contentRepository = contentRepository;
}

public ContentItem createContent(String type, Map<String, Object> data, User author) {
ContentItem content = new ContentItem();
content.setType(type);
content.setData(data);
content.setAuthor(author);
content.setCreatedAt(new Date());
content.setUpdatedAt(new Date());
content.setPublished(false);

return contentRepository.save(content);
}

public ContentItem addComment(String contentId, Comment comment) {
ContentItem content = contentRepository.findById(contentId)
.orElseThrow(() -> new ContentNotFoundException("Content not found"));

if (content.getComments() == null) {
content.setComments(new ArrayList<>());
}

content.getComments().add(comment);
content.setUpdatedAt(new Date());

return contentRepository.save(content);
}

// Easily add new fields without migrations
public ContentItem addMetadata(String contentId, String key, Object value) {
ContentItem content = contentRepository.findById(contentId)

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