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Texaryn

JSON Schema support

Texaryn’s @texaryn/schema-json adapter supports Draft 7, 2019-09 and 2020-12, with automatic dialect detection. Draft support identifies the schema dialect used by the adapter; it is not a claim that every keyword produces a form control or that Texaryn provides full specification compliance.

Supported dialects

Section titled “Supported dialects”
Draft $schema value Status
Draft 7 http://json-schema.org/draft-07/schema# Supported
2019-09 https://json-schema.org/draft/2019-09/schema Supported
2020-12 https://json-schema.org/draft/2020-12/schema Supported
Draft 4 and Draft 6 Not supported

The adapter reads $schema. A missing or unrecognized value falls back to Draft 7, rather than rejecting the schema. Set defaultDialect to change that fallback; it does not override a recognized $schema value.

import { createJsonSchemaAdapter } from '@texaryn/schema-json'


const adapter = await createJsonSchemaAdapter(schema, {
  defaultDialect: '2020-12',
})

Use an explicit $schema value when sharing schemas so that the intended dialect is clear.

Form generation capabilities

Section titled “Form generation capabilities”

The adapter projects schemas and current data into fields, constraints and annotations for the renderer. The following describes that projection scope, separately from validation.

Capability Draft 7 2019-09 2020-12 Form behavior
Objects and fields type, properties, required Same Same Declared properties appear even before data is entered.
Local references $ref, definitions $ref, $defs $ref, $defs Referenced field schemas are resolved locally.
Composition allOf, anyOf, oneOf Same Same allOf contributes all branches; anyOf/oneOf selection depends on current data.
Conditionals if, then, else Same Same Inactive branch fields remain in the projection with active: false.
Dependencies dependencies dependentSchemas, dependentRequired Same as 2019-09 Present trigger properties activate dependent fields or required flags.
Homogeneous arrays Schema-valued items Same Same Item fields are projected for entries present in the data.
Choices enum Same Same Enum values become options for the renderer.
String constraints minLength, maxLength, pattern Same Same Constraints are exposed to widgets.
Numeric constraints minimum, maximum, exclusiveMinimum, exclusiveMaximum, multipleOf Same Same Constraints are exposed to widgets.
Array constraints minItems, maxItems, uniqueItems Same Same Constraints are exposed in the projection.
Field metadata title, description, default, examples, readOnly, writeOnly, format Same, plus deprecated Same as 2019-09 Metadata is passed to the runtime and widgets; it does not guarantee a dedicated control.

Projection has these limits:

  • Tuple arrays (array-valued items in older drafts or prefixItems in 2020-12) do not have a dedicated projection path. Use homogeneous arrays for generated item controls.
  • patternProperties and additionalProperties do not generate fields for arbitrary object keys. Declare editable fields in properties.
  • Boolean schemas and schemas without a resolvable type do not produce ordinary field nodes. For a type array, projection uses the first recognized type rather than creating a type selector.
  • Unresolved oneOf object branches can remain inactive. The fallback does not cover unresolved primitive alternatives; a union is not automatically a branch picker.
  • Remote schema loading, $recursiveRef and $dynamicRef are outside the documented form projection scope. Use local $ref for reusable fields.

Validation scope

Section titled “Validation scope”

validate(data) delegates to json-schema-library using the selected draft, then normalizes errors to JSON Pointer locations and keyword names. Validation can enforce constraints that have no corresponding form control, such as const, not, contains or restrictions on additional properties. Newer draft keywords such as minContains, maxContains, unevaluatedProperties and unevaluatedItems are delegated to that library; they are not an independent Texaryn compliance guarantee.

For 2020-12, the adapter explicitly disables format assertions. A value such as format: 'email' remains available as field metadata but does not make an invalid email fail validation. Draft 7 and 2019-09 use the validation library’s default format behavior. The adapter does not expose a format assertion configuration option.

validateAt(data, pointer) validates the full instance and filters errors to the requested pointer and its descendants. It does not compile or validate an isolated subschema.

These capabilities describe the public @texaryn/schema-json adapter. The private Hyperjump adapter is used to test the schema port abstraction and is not the adapter installed by the getting started guide.

Continue with Getting started to create a form, or try schemas in the playground.