website/docs/guide/walkthrough/services.md

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:::tip This is version 3 api only!! :::

Services

:::tip TLDR: The direct upgrade to useContainer. if you set up a bot with create-bot, check dependencies.d.ts. Dependencies are the types that Services uses. :::

You need someway to use dependencies in your command module. Services to the rescue!

import { CoreDependencies, Singleton } from '@sern/handler'
import { Client } from 'discord.js'

interface Dependencies extends CoreDependencies { 
    '@sern/client': Singleton<Client>
}

Recall, some keys in Dependencies are special.

Special key dependency must implement its contracts.

• @sern/client: Your discord client. -> Emitter
• @sern/logger: Log data -> Logging
• @sern/errors: Handling errors and lifetime -> ErrorHandling
• @sern/modules: Managing all command modules -> ModuleManager
• @sern/emitter: is the key to emit events and occurences in a project -> Emitter

Lets try to access the client you provided.

import { Service } from '@sern/handler'

export default commandModule({ 
   // ...
    execute: (ctx) => {
        //Client!
        const client = Service('@sern/client');
    }
   // 
})

Safety

• Services cannot be called in other services while makeDependencies is forming.
• You will need to wire dependencies together.

import Tabs from '@theme/Tabs';import TabItem from '@theme/TabItem';

✅ A good example; ```ts title="index.ts" showLineNumbers // index.ts await makeDependencies(...pass you options here) ``` ```ts // commands/ping.ts // This is guaranteed to be defined if configured correctly import { Service } from '@sern/handler'; const client = Service('@sern/client'); ``` ❌ Don't do this ```ts title="commands/ping.ts" showLineNumbers import { Service, makeDependencies } from '@sern/handler'; /* DON'T USE SERVICES BEFORE CALLING makeDependencies */ const logger = Service('@sern/logger');

await makeDependencies()

</TabItem>
</Tabs>

- Services can only be used after sern has made dependencies. 
    - Calling a service before will crash your application. 
- Services can be safely used outside of commandModules. 
    - Be careful to not cause too many side effects.


## Related api
- use `Service` for single dependency.
- use `Services` for multiple dependencies.