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- codegen: Low-code React app with JSON-driven component system - packagerepo: Schema-driven package repository with backend/frontend - postgres: Next.js app with Drizzle ORM and PostgreSQL Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>
63 lines
1.4 KiB
Markdown
63 lines
1.4 KiB
Markdown
# JSON Expression System
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This document describes the supported JSON expression patterns used across JSON UI schemas.
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Legacy compute functions have been removed in favor of expression strings and value templates.
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## Core Concepts
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### Expressions
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Expressions are string values that resolve against a data + event context:
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```json
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{
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"expression": "event.target.value"
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}
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```
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Supported expression patterns:
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- `data` or `event`
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- Dot access: `data.user.name`, `event.target.value`
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- Literals: numbers, booleans, `null`, `undefined`, quoted strings
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- Time: `Date.now()`
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- Array filtering:
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- `data.todos.filter(completed === true)`
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- `data.users.filter(status === 'active').length`
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### Value Templates
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Value templates are JSON objects whose string values are evaluated as expressions:
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```json
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{
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"valueTemplate": {
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"id": "Date.now()",
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"text": "data.newTodo",
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"completed": false
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}
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}
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```
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### Conditions
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Conditions use expression strings that are evaluated against the data context:
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```json
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{
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"condition": "data.newTodo.length > 0"
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}
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```
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Supported condition patterns:
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- `data.field > 0`
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- `data.field.length > 0`
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- `data.field === 'value'`
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- `data.field != null`
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## Legacy Compute Functions (Removed)
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Schemas should no longer reference function names in `compute`, `transform`, or string-based
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condition fields. Use `expression` and `valueTemplate` instead.
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