Core Package Overview

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Installation

npm install @jsonforms/core

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Key Exports

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Actions

• init - Initialize JSON Forms with data, schema, and UI schema
• update - Update form data at a specific path
• setSchema - Update the JSON schema
• setUISchema - Update the UI schema
• registerRenderer - Register a custom renderer
• setConfig - Set form configuration

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Reducers

• coreReducer - Handles core state (data, schema, validation)
• jsonFormsReducerConfig - Complete reducer configuration

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Testers

• rankWith - Create a ranked tester
• isControl - Check if UI schema is a control
• schemaTypeIs - Test schema type
• formatIs - Test schema format
• and, or, not - Compose testers

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Utilities

• Path utilities (composePaths, toDataPath)
• Schema resolution (resolveSchema, resolveData)
• Validation (createAjv, validate)
• Label generation (createLabelDescriptionFrom)
• Runtime evaluation (isVisible, isEnabled)

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Usage Example

import {
  init,
  coreReducer,
  rankWith,
  isControl,
  schemaTypeIs
} from '@jsonforms/core';

// Initialize JSON Forms
const initAction = init(
  { name: 'John' },
  {
    type: 'object',
    properties: {
      name: { type: 'string' }
    }
  }
);

// Create a tester for string controls
const stringControlTester = rankWith(
  3,
  and(isControl, schemaTypeIs('string'))
);

​

TypeScript Support

import type {
  JsonSchema,
  UISchemaElement,
  ControlElement,
  RankedTester,
  Tester
} from '@jsonforms/core';