Collections in Orionjs provide a type-safe interface to MongoDB collections with automatic schema validation and helpful query methods.

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Creating Collections

There are two main ways to create collections in Orionjs: The recommended approach is to use the repository pattern with proper typing: 
import {Repository} from '@orion-js/services'
import {createCollection, typedId, OptionalId} from '@orion-js/mongodb'
import {schemaWithName, InferSchemaType} from '@orion-js/schema'

const UserSchema = schemaWithName('UserSchema', {
  _id: {type: typedId('user')},
  name: {type: String},
  email: {type: String, optional: true}
})

type UserType = InferSchemaType<typeof UserSchema>

@Repository()
export class UserRepository {
  users = createCollection({
    name: 'users',
    schema: UserSchema,
    // Other options...
  })
  
  async findByEmail(email: string): Promise<UserType | null> {
    return await this.users.findOne({email})
  }
  
  async createUser(userData: OptionalId<UserType>): Promise<string> {
    return await this.users.insertOne(userData)
  }
}

​
Using createCollection Directly

You can also create collections directly: 
import {createCollection, typedId} from '@orion-js/mongodb'
import {schemaWithName, InferSchemaType} from '@orion-js/schema'

const UserSchema = schemaWithName('UserSchema', {
  _id: {type: typedId('user')},
  name: {type: String},
  email: {type: String, optional: true}
})

type UserType = InferSchemaType<typeof UserSchema>

const Users = createCollection({
  name: 'users',
  schema: UserSchema,
  // Other options...
})

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Configuration Options

The createCollection function accepts the following options: 
{
  // Required options
  name: string,             // Collection name in MongoDB
  schema: SchemaType,       // Schema for validation and typing

  // Optional options
  connectionName: string,   // Connection name (default: 'main')
  idGeneration: 'mongo' | 'random' | 'uuid', // ID generation method (default: 'mongo')
  indexes: Index[],         // Array of indexes to create
}

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ID Generation

Orionjs offers several options for generating document IDs: 
const Users = createCollection({
  name: 'users',
  schema: UserSchema,
  idGeneration: 'uuid' // Generate UUIDs for _id
})

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Basic ID Generation Options

  • 'mongo' (default): MongoDB ObjectId strings (time-based)
  • 'random': Random string IDs
  • 'uuid': UUID v7 strings

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Typed IDs

For TypeScript users, Orionjs provides powerful ways to create type-safe IDs using typedId: 
import {typedId} from '@orion-js/mongodb'
import {schemaWithName, InferSchemaType} from '@orion-js/schema'

const UserSchema = schemaWithName('UserSchema', {
  _id: {type: typedId('user')}, // Will create IDs like 'user-abc123'
  name: {type: String},
  email: {type: String}
})

type UserType = InferSchemaType<typeof UserSchema>
// UserType._id will be typed as `user-${string}`

const Users = createCollection({
  name: 'users',
  schema: UserSchema
})
The library will automatically detect typedId from the schema and use it to create prefixed IDs.

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Indexes

Define indexes to optimize queries: 
const Users = createCollection({
  name: 'users',
  schema: UserSchema,
  indexes: [
    {
      keys: { email: 1 },
      options: { unique: true }
    },
    {
      keys: { createdAt: -1 }
    }
  ]
})

​
Collection Types

When using TypeScript, properly type your collections: 
// Infer type from schema
type UserType = InferSchemaType<typeof UserSchema>

// For document creation (without _id)
type NewUserType = OptionalId<UserType>

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Getting a Collection Instance

If you need to access a collection outside a repository: 
import {getInstance} from '@orion-js/services'
import {UserRepository} from './UserRepository'

// Get the repository
const userRepo = getInstance(UserRepository)

// Use repository methods
const user = await userRepo.findByEmail('user@example.com')
Collections provide a solid foundation for working with MongoDB in Orionjs, with built-in type safety and schema validation to make your database operations more reliable.