allOf JSON Schema Keyword JSON Schema

Composition

Schema template

JSON Schema

{
  "allOf": [
    {
      "type": "object"
    },
    {
      "properties": {
        "id": {
          "type": "string"
        }
      },
      "required": [
        "id"
      ]
    }
  ]
}

Valid example JSON

{
  "id": "item_1"
}

Invalid example JSON

{}

Fields

Field	Type	Required	Description
`allOf`	schema[]	Yes	Every schema in the array must pass. This is composition, not automatic object inheritance merging.

How to use this schema

Use allOf to combine base constraints with specialized constraints. Test error output carefully because deeply nested allOf chains can be harder to debug.

Version support and combinations

This keyword or pattern is commonly supported across modern JSON Schema workflows. Check your validator for Draft-04, Draft-07, 2019-09, and 2020-12 behavior before relying on newer composition or conditional features.

Common combination: pair this reference with type, required, and properties so validation errors are specific enough for API clients and form users.

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allOf JSON Schema Keyword