@auto-engineer/server-generator-apollo-emmett

Code generation that scaffolds event-sourced GraphQL servers using the Emmett framework.

---

Purpose

Without @auto-engineer/server-generator-apollo-emmett, you would have to manually write event sourcing boilerplate, create GraphQL resolvers, define command/event types, and set up projections for every slice in your server.

This package transforms narrative specifications into a complete Apollo GraphQL server with commands, events, projections, queries, and reactors following the Emmett event sourcing patterns.

---

Installation

``bash
pnpm add @auto-engineer/server-generator-apollo-emmett
`

Quick Start

Register the handler and generate a server:

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`typescript
import { COMMANDS } from '@auto-engineer/server-generator-apollo-emmett';
import { createMessageBus } from '@auto-engineer/message-bus';

const bus = createMessageBus();
COMMANDS.forEach(cmd => bus.registerCommand(cmd));
`

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`typescript
const result = await bus.dispatch({
type: 'GenerateServer',
data: {
modelPath: './.context/schema.json',
destination: '.',
},
requestId: 'req-123',
});

console.log(result);
// → { type: 'ServerGenerated', data: { serverDir: './server', destination: '.' } }
`

The command generates a complete server directory with Apollo, Emmett, and type-graphql.

---

How-to Guides

$3

`bash
auto generate:server --model-path=./.context/schema.json --destination=.
`

$3

`typescript
import { COMMANDS } from '@auto-engineer/server-generator-apollo-emmett';
import { createMessageBus } from '@auto-engineer/message-bus';

const bus = createMessageBus();
COMMANDS.forEach(handler => bus.register(handler));

await bus.send({
type: 'GenerateServer',
data: {
modelPath: './.context/schema.json',
destination: '.',
},
});
`

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`typescript
if (result.type === 'ServerGenerationFailed') {
console.error(result.data.error);
}
`

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`typescript
bus.on('SliceGenerated', (event) => {
console.log(Generated: ${event.data.flowName}/${event.data.sliceName});
});
`

---

API Reference

$3

`typescript
import { COMMANDS } from '@auto-engineer/server-generator-apollo-emmett';

import type {
GenerateServerCommand,
ServerGeneratedEvent,
ServerGenerationFailedEvent,
SliceGeneratedEvent,
} from '@auto-engineer/server-generator-apollo-emmett';
`

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| Command | CLI Alias | Description |
|---------|-----------|-------------|
| GenerateServer | generate:server | Generate event-sourced GraphQL server |

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`typescript
type GenerateServerCommand = Command<
'GenerateServer',
{
modelPath: string;
destination: string;
}
>;
`

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`typescript
type ServerGeneratedEvent = Event<
'ServerGenerated',
{
modelPath: string;
destination: string;
serverDir: string;
contextSchemaGraphQL?: string;
}
>;
`

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`typescript
type SliceGeneratedEvent = Event<
'SliceGenerated',
{
flowName: string;
sliceName: string;
sliceType: string;
schemaPath: string;
slicePath: string;
}
>;
`

---

Architecture

`
src/
├── index.ts
├── server.ts
├── commands/
│ └── generate-server.ts
├── codegen/
│ ├── scaffoldFromSchema.ts
│ ├── extract/
│ └── templates/
│ ├── command/
│ ├── query/
│ └── react/
├── domain/shared/
└── utils/
`

The following diagram shows the generation flow:

`mermaid
flowchart TB
A[GenerateServer] --> B[Load Model JSON]
B --> C[Extract Messages from Specs]
C --> D[Build GWT Mappings]
D --> E[Render EJS Templates]
E --> F[Write Files to Disk]
F --> G[ServerGeneratedEvent]
`

Flow: Command loads model, extracts commands/events, renders templates, writes generated server.

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`
server/
├── src/
│ ├── server.ts
│ ├── utils/
│ └── domain/
│ ├── shared/
│ └── flows/
│ └── {flow-name}/
│ └── {slice-name}/
│ ├── commands.ts
│ ├── events.ts
│ ├── state.ts
│ ├── decide.ts
│ ├── evolve.ts
│ └── mutation.resolver.ts
├── package.json
└── tsconfig.json
`

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| Type | Description |
|------|-------------|
| Command | Mutation resolvers with decide/evolve pattern |
| Query | Query resolvers backed by projections |
| React | Reactors responding to events with commands |

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| Package | Usage |
|---------|-------|
| @auto-engineer/narrative | Model type definitions |
| @auto-engineer/message-bus | Command/event infrastructure |
| @event-driven-io/emmett | Event sourcing framework |
| apollo-server | GraphQL server runtime |
| type-graphql | GraphQL schema decorators |
| ejs` | Template rendering |