API Filtering & Sorting

Table of Contents

• Overview
• When to Use
• Quick Start
• Reference Guides
• 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	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