Filtering with Range — Numeric and Date Range Queries

In this tutorial, you will learn about Filtering with Range. We cover key concepts, practical examples, and best practices to help you master this topic.

Range filtering lets clients filter records within numeric or date ranges using min/max or before/after parameter conventions for bounded data queries.

Request Format

GET /api/products?price_min=10&price_max=100
GET /api/orders?created_after=2026-01-01&created_before=2026-06-28
GET /api/users?age_gte=18&age_lte=65

Implementation

app.get("/api/products", async (req, res) => {
  const { price_min, price_max } = req.query;
  const conditions = [];
  const params = [];
  let idx = 1;

  if (price_min) {
    conditions.push(`price >= $${idx++}`);
    params.push(parseFloat(price_min));
  }
  if (price_max) {
    conditions.push(`price <= $${idx++}`);
    params.push(parseFloat(price_max));
  }

  const where = conditions.length
    ? `WHERE ${conditions.join(" AND ")}`
    : "";
  const result = await db.query(`SELECT * FROM products ${where}`, params);
  res.json({ data: result.rows });
});

Naming Conventions

# Common range parameter conventions:
# Closed range:
price_min / price_max
# Suffix-based:
price_gte / price_lte    # greater than or equal / less than or equal
price_gt / price_lt      # strict greater than / less than

Common Mistakes

1. No boundary validation — Accepting illogical ranges like price_min > price_max.
2. Inclusive vs exclusive confusion — Not documenting whether ranges are inclusive.
3. Date format ambiguity — Not specifying the date format (ISO 8601 recommended).

Practice Questions

1. How do you filter records within a price range?
2. What naming conventions work for range parameters?
3. Why validate range boundaries server-side?

Challenge

Implement range filtering for a hotel booking API with price range, date range (check-in to check-out), and guest count range.

What's Next

In the next lesson, you will learn text search filtering.