Integer Range Validation with minimum and maximum

Integer Range Validation

Constraining integers to a valid range is one of the most common validation tasks. JSON Schema's minimum and maximum keywords let you define inclusive bounds for numeric values.

Basic Range Schema

{
  "type": "integer",
  "minimum": 1,
  "maximum": 100
}

This accepts whole numbers from 1 to 100, inclusive on both ends. Values like 0, 101, -5, and 50.5 are all rejected — 0 and 101 are out of range, -5 is below the minimum, and 50.5 is not an integer.

How the Example Schema Works

The schema defines three fields with domain-specific integer ranges:

1. port — TCP/UDP port numbers range from 1 to 65535. The schema enforces this with minimum: 1 (port 0 is reserved) and maximum: 65535 (the highest valid port number for a 16-bit unsigned integer).

2. httpStatusCode — valid HTTP status codes range from 100 (Continue) to 599 (the upper boundary of the 5xx server error class). This prevents invalid codes like 99 or 600 from reaching your application logic.

3. priority — a simple 0-10 priority scale where 0 is lowest and 10 is highest. This is a common pattern for task management and job queue systems.

The test data passes: 8080 is in [1, 65535], 200 is in [100, 599], and 5 is in [0, 10].

Inclusive vs. Exclusive Bounds

JSON Schema offers both inclusive and exclusive bounds:

{
  "minimum": 0,           // >= 0  (inclusive)
  "maximum": 100,         // <= 100 (inclusive)
  "exclusiveMinimum": 0,  // > 0   (exclusive)
  "exclusiveMaximum": 100 // < 100 (exclusive)
}

You can mix these — for example, exclusiveMinimum: 0 with maximum: 100 accepts values in the range (0, 100].

Draft 4 vs. Modern Drafts

In Draft 4, exclusiveMinimum and exclusiveMaximum were boolean modifiers on minimum/maximum. Starting from Draft 6, they became standalone numeric keywords. Be aware of this if your validator uses an older draft.

Practical Tips

• Port validation: Remember that ports 1-1023 are "well-known" and typically require root/admin privileges. Consider using minimum: 1024 for user-configurable ports.
• Pagination: For page numbers, use minimum: 1 (pages are 1-indexed). For page sizes, combine with multipleOf to enforce round numbers.