Dependent Required Properties in JSON Schema

Dependent Required Properties

The dependentRequired keyword creates conditional presence rules: if a certain property exists in the object, then one or more other properties must also exist. This is different from required, which always mandates presence.

Basic Syntax

{
  "dependentRequired": {
    "creditCard": ["billingAddress", "expiryDate"]
  }
}

This means: if the creditCard property is present, then billingAddress and expiryDate must also be present. If creditCard is absent, the rule is not enforced — billingAddress and expiryDate can be absent too.

How the Example Schema Works

The schema models a checkout form with two dependency rules:

1. creditCard → billingAddress: If a credit card number is provided, the billing address becomes mandatory. You cannot submit a card without an address to charge it to.

2. couponCode → couponSource: If a coupon code is used, the marketing source must be specified. This enables analytics tracking for promotional campaigns.

The test data passes because:

• creditCard is present, and so is billingAddress — dependency satisfied.
• couponCode is present, and so is couponSource — dependency satisfied.
• name is present, satisfying the required constraint.

One-Way Dependencies

Note that dependentRequired is one-directional. The rule "creditCard": ["billingAddress"] does NOT mean the reverse — a billingAddress can exist without a creditCard. If you need bidirectional dependencies, declare both directions:

{
  "dependentRequired": {
    "creditCard": ["billingAddress"],
    "billingAddress": ["creditCard"]
  }
}

Draft History

• Draft 2020-12: Uses dependentRequired (present example).
• Draft 7 and earlier: Used dependencies keyword, which combined both property dependencies and schema dependencies in a single keyword. The modern drafts split this into dependentRequired (property presence) and dependentSchemas (conditional schema application).

Comparison with if/then

dependentRequired only checks property presence. If you need to check property values (e.g., "if paymentMethod is credit_card, then require cardNumber"), use if/then/else instead. See the conditional-if-then-else example for that pattern.

When to Use

• Payment forms: card number requires billing address and expiry
• Shipping: domestic shipping requires state; international requires country code
• Analytics: campaign code requires campaign source and medium