43 lines
1.1 KiB
Markdown
43 lines
1.1 KiB
Markdown
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# Dependency Injection
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When scaling up your bot to multiple files, you may find it useful to inject dependencies
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into the children dispatchers instead of having to pass them around manually.
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`@mtcute/dispatcher` provides a simple service locator that you can use to inject dependencies:
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```ts
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// for typescript, you need to declare the dependencies
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declare module '@mtcute/dispatcher' {
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interface DispatcherDependencies {
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db: Database
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}
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}
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// create a root dispatcher
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const dp = Dispatcher.for(tg)
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// inject the database
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dp.inject('db', new Database())
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// or
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dp.inject({ db: new Database() })
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// and then add a child dispatcher
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import { childDispatcher } from './file2'
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dp.addChild(childDispatcher)
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// file2.ts
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const dp = Dispatcher.child()
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dp.onNewMessage(async (ctx) => {
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// the dependencies are available in dp.deps
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const db = dp.deps.db
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await db.saveMessage(ctx.message)
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})
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export const childDispatcher = dp
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```
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::: info
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You can only inject dependencies into the root dispatcher (the one created with `Dispatcher.for`),
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and they will be available in *all* children dispatchers.
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:::
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