# @windychen/trans-form-middleware

Node.js ESM library that parses filter arrays emitted by `@windychen/trans-form-component` into structured conditions. **Does not generate SQL** — ORM adapters consume the output.

> 版本 0.1.0 — 首个可发布版本：`parseFilters` / `mapOperators` / `toTree` / `splitMultiValue`，零依赖，纯 ESM。

## Install

```bash
npm install @windychen/trans-form-middleware
```

## Usage

```js
import { parseFilters } from '@windychen/trans-form-middleware';

const componentOutput = [
  { field: 'name', value: 'xx', query: 'EQ' },
  { field: 'tags', value: 'a,b,c', query: 'IN', logic: 'OR' },
];

const filters = parseFilters(componentOutput, {
  allowedFields: ['name', 'tags', 'status'],
  mode: 'pass-through',
  unknownField: 'error',
  skipEmpty: false,
});
```

See `DESIGN.md` for the full protocol and grill-me decisions (Q1–Q61).

## API

| Export | Description |
|--------|-------------|
| `parseFilters(conditions, options)` | Main parser |
| `mapOperators(query, operatorMap?)` | Map EQ/GT/… to op symbols |
| `toTree(flat)` | Nest flat array by logic |
| `splitMultiValue(query, value)` | Parse comma-separated multi-values |
| `DEFAULT_OPERATOR_MAP` | Built-in operator mapping |

### parseOptions

| Option | Default | Description |
|--------|---------|-------------|
| `allowedFields` | *(required)* | Whitelist of field names |
| `mode` | `'pass-through'` | `'flat'` \| `'tree'` \| `'pass-through'` |
| `unknownField` | `'error'` | `'error'` \| `'skip'` |
| `strict` | `false` | Validate item shape |
| `operatorMap` | `{}` | Merge/override operator mapping |
| `skipFlags` | `['disabled','hidden']` | Skip items with these truthy flags |
| `skipEmpty` | `false` | Skip items with `empty: true` |

## Development

```bash
npm install
npm test
```

## License

MIT