Schema Composition

JSON Schema includes a few keywords for combining schemas together. Note that this doesn't necessarily mean combining schemas from multiple files or JSON trees, though these facilities help to enable that and are described in Structuring a complex schema. Combining schemas may be as simple as allowing a value to be validated against multiple criteria at the same time.

These keywords correspond to well known boolean algebra concepts like AND, OR, XOR, and NOT. You can often use these keywords to express complex constraints that can't otherwise be expressed with standard JSON Schema keywords.

The keywords used to combine schemas are:

• allOf : (AND) Must be valid against all of the subschemas
• anyOf : (OR) Must be valid against any of the subschemas
• oneOf : (XOR) Must be valid against exactly one of the subschemas

All of these keywords must be set to an array, where each item is a schema. Be careful with recursive schemas as they can exponentially increase processing times.

In addition, there is:

• not : (NOT) Must not be valid against the given schema

allOf

To validate against allOf , the given data must be valid against all of the given subschemas.