SKILL.md
API Filtering & Sorting
Table of Contents
- [Overview](#overview)
- [When to Use](#when-to-use)
- [Quick Start](#quick-start)
- [Reference Guides](#reference-guides)
- [Best Practices](#best-practices)
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:
// 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](references/query-parameter-filtering.md) | Query Parameter Filtering |
| [Advanced Filter Parser](references/advanced-filter-parser.md) | Advanced Filter Parser |
| [Filter Builder Pattern](references/filter-builder-pattern.md) | Filter Builder Pattern |
| [Python Filtering (SQLAlchemy)](references/python-filtering-sqlalchemy.md) | Python Filtering (SQLAlchemy) |
| [Elasticsearch Filtering](references/elasticsearch-filtering.md) | Elasticsearch Filtering |
| [Query Validation](references/query-validation.md) | 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