API Filtering & Sorting
Table of Contents
Overview
Build flexible filtering and sorting systems that handle complex queries efficiently with proper validation, security, and performance optimization.
When to Use
- Building search and filter interfaces
- Implementing advanced query capabilities
- Creating flexible data retrieval endpoints
- Optimizing query performance
- Validating user input for queries
- Supporting complex filtering logic
Quick Start
Minimal working example:
javascript// Node.js filtering implementation app.get("/api/products", async (req, res) => { const filters = {}; const sortOptions = {}; // Parse filtering parameters const allowedFilters = [ "category", "minPrice", "maxPrice", "inStock", "rating", ]; for (const key of allowedFilters) { if (req.query[key]) { filters[key] = req.query[key]; } } // Build MongoDB query const mongoQuery = {}; if (filters.category) { mongoQuery.category = filters.category; } // ... (see reference guides for full implementation)
Reference Guides
Detailed implementations in the references/ directory:
| Guide | Contents |
|---|---|
| Query Parameter Filtering | Query Parameter Filtering |
| Advanced Filter Parser | Advanced Filter Parser |
| Filter Builder Pattern | Filter Builder Pattern |
| Python Filtering (SQLAlchemy) | Python Filtering (SQLAlchemy) |
| Elasticsearch Filtering | Elasticsearch Filtering |
| Query Validation | Query Validation |
Best Practices
✅ DO
- Whitelist allowed filter fields
- Validate all input parameters
- Index fields used for filtering
- Support common operators
- Provide faceted navigation
- Cache filter options
- Limit filter complexity
- Document filter syntax
- Use database-native operators
- Optimize queries with indexes
❌ DON'T
- Allow arbitrary field filtering
- Support unlimited operators
- Ignore SQL injection risks
- Create complex filter logic
- Expose internal field names
- Filter on unindexed fields
- Allow deeply nested filters
- Skip input validation
- Combine all filters with OR
- Ignore performance impact
