json-render-react-native

@json-render/react-native

React Native renderer that converts JSON specs into native mobile component trees with standard components, data binding, visibility, actions, and dynamic props.

Quick Start

import { defineCatalog } from "@json-render/core";
import { schema } from "@json-render/react-native/schema";
import {
  standardComponentDefinitions,
  standardActionDefinitions,
} from "@json-render/react-native/catalog";
import { defineRegistry, Renderer, type Components } from "@json-render/react-native";
import { z } from "zod";

// Create catalog with standard + custom components const catalog = defineCatalog(schema, { components: { ...standardComponentDefinitions, Icon: { props: z.object({ name: z.string(), size: z.number().nullable(), color: z.string().nullable() }), slots: [], description: "Icon display", }, }, actions: standardActionDefinitions, });

// Register only custom components (standard ones are built-in) const { registry } = defineRegistry(catalog, { components: { Icon: ({ props }) => <Ionicons name={props.name} size={props.size ?? 24} />, } as Components, });

// Render function App({ spec }) { return ( ); }

## Standard Components

### Layout
- `Container` - wrapper with padding, background, border radius
- `Row` - horizontal flex layout with gap, alignment
- `Column` - vertical flex layout with gap, alignment
- `ScrollContainer` - scrollable area (vertical or horizontal)
- `SafeArea` - safe area insets for notch/home indicator
- `Pressable` - touchable wrapper that triggers actions on press
- `Spacer` - fixed or flexible spacing
- `Divider` - thin line separator

### Content
- `Heading` - heading text (levels 1-6)
- `Paragraph` - body text
- `Label` - small label text
- `Image` - image display with sizing modes
- `Avatar` - circular avatar image
- `Badge` - small status badge
- `Chip` - tag/chip for categories

### Input
- `Button` - pressable button with variants
- `TextInput` - text input field
- `Switch` - toggle switch
- `Checkbox` - checkbox with label
- `Slider` - range slider
- `SearchBar` - search input

### Feedback
- `Spinner` - loading indicator
- `ProgressBar` - progress indicator

### Composite
- `Card` - card container with optional header
- `ListItem` - list row with title, subtitle, accessory
- `Modal` - bottom sheet modal

## Visibility Conditions

Use `visible` on elements. Syntax: `{ "$state": "/path" }`, `{ "$state": "/path", "eq": value }`, `{ "$state": "/path", "not": true }`, `[ cond1, cond2 ]` for AND.

## Pressable + setState Pattern

Use `Pressable` with the built-in `setState` action for interactive UIs like tab bars:

```json
{
  "type": "Pressable",
  "props": {
    "action": "setState",
    "actionParams": { "statePath": "/activeTab", "value": "home" }
  },
  "children": ["home-icon", "home-label"]
}

Dynamic Prop Expressions

Any prop value can be a data-driven expression resolved at render time:

• { "$state": "/state/key" } - reads from state model (one-way read)
• { "$bindState": "/path" } - two-way binding: use on the natural value prop (value, checked, pressed, etc.) of form components.
• { "$bindItem": "field" } - two-way binding to a repeat item field. Use inside repeat scopes.
• { "$cond": <condition>, "$then": <value>, "$else": <value> } - conditional value

{
  "type": "TextInput",
  "props": {
    "value": { "$bindState": "/form/email" },
    "placeholder": "Email"
  }
}

Components do not use a statePath prop for two-way binding. Use { "$bindState": "/path" } on the natural value prop instead.

Built-in Actions

The setState action is handled automatically by ActionProvider and updates the state model directly, which re-evaluates visibility conditions and dynamic prop expressions:

{ "action": "setState", "actionParams": { "statePath": "/activeTab", "value": "home" } }

Providers

Provider	Purpose
StateProvider	Share state across components (JSON Pointer paths). Accepts optional store prop for controlled mode.
ActionProvider	Handle actions dispatched from components
VisibilityProvider	Enable conditional rendering based on state
ValidationProvider	Form field validation

External Store (Controlled Mode)

Pass a StateStore to StateProvider (or JSONUIProvider / createRenderer) to use external state management:

import { createStateStore, type StateStore } from "@json-render/react-native";

const store = createStateStore({ count: 0 });

<StateProvider store={store}>{children}</StateProvider>

store.set("/count", 1); // React re-renders automatically

When store is provided, initialState and onStateChange are ignored.

Key Exports

Export	Purpose
defineRegistry	Create a type-safe component registry from a catalog
Renderer	Render a spec using a registry
schema	React Native element tree schema
standardComponentDefinitions	Catalog definitions for all standard components
standardActionDefinitions	Catalog definitions for standard actions
standardComponents	Pre-built component implementations
createStandardActionHandlers	Create handlers for standard actions
useStateStore	Access state context
useStateValue	Get single value from state
useBoundProp	Two-way state binding via $bindState/$bindItem
useStateBinding	(deprecated) Legacy two-way binding by path
useActions	Access actions context
useAction	Get a single action dispatch function
useUIStream	Stream specs from an API endpoint
createStateStore	Create a framework-agnostic in-memory StateStore
StateStore	Interface for plugging in external state management