Common Adapter Patterns

import { MongoDBService } from '@feathersjs/mongodb'
import type { Params } from '@feathersjs/feathers'

interface Article {
  _id: ObjectId
  title: string
  content: string
  createdAt: Date
  updatedAt: Date
}

class ArticleService extends MongoDBService<Article> {
  async create(data: Partial<Article>, params?: Params) {
    const articleData = {
      ...data,
      createdAt: new Date(),
      updatedAt: new Date()
    }
    return super.create(articleData, params)
  }

  async patch(id: any, data: Partial<Article>, params?: Params) {
    const patchData = {
      ...data,
      updatedAt: new Date()
    }
    return super.patch(id, patchData, params)
  }
}

import { MongoDBService } from '@feathersjs/mongodb'

class TenantService extends MongoDBService {
  async find(params?: Params) {
    const tenantId = params?.user?.tenantId
    if (!tenantId) {
      throw new Forbidden('No tenant context')
    }
    
    return super.find({
      ...params,
      query: {
        ...params?.query,
        tenantId
      }
    })
  }

  async create(data: any, params?: Params) {
    const tenantId = params?.user?.tenantId
    if (!tenantId) {
      throw new Forbidden('No tenant context')
    }
    
    return super.create({
      ...data,
      tenantId
    }, params)
  }

  async get(id: any, params?: Params) {
    const tenantId = params?.user?.tenantId
    return super.get(id, {
      ...params,
      query: {
        ...params?.query,
        tenantId
      }
    })
  }
}

// Find records in date range
const startDate = new Date('2024-01-01')
const endDate = new Date('2024-12-31')

const results = await app.service('orders').find({
  query: {
    createdAt: {
      $gte: startDate,
      $lte: endDate
    },
    status: 'completed'
  }
})

// Efficient pagination for large datasets
interface CursorParams extends Params {
  query?: {
    cursor?: string
    $limit?: number
  }
}

class CursorService extends MongoDBService {
  async find(params?: CursorParams) {
    const limit = params?.query?.$limit || 20
    const cursor = params?.query?.cursor
    
    const query: any = {}
    
    if (cursor) {
      // Decode cursor (in practice, use proper encoding)
      query._id = { $gt: new ObjectId(cursor) }
    }
    
    const results = await super.find({
      ...params,
      query: {
        ...params?.query,
        ...query,
        $limit: limit,
        $sort: { _id: 1 }
      },
      paginate: false
    })
    
    const hasMore = results.length === limit
    const nextCursor = hasMore
      ? results[results.length - 1]._id.toString()
      : null
    
    return {
      data: results,
      nextCursor,
      hasMore
    }
  }
}

// Only fetch needed fields
const users = await app.service('users').find({
  query: {
    status: 'active',
    $select: ['id', 'name', 'email']
    // Exclude large fields like 'bio', 'avatar', etc.
  }
})

import { HookContext } from '@feathersjs/feathers'

const cache = new Map()

const cacheResults = async (context: HookContext) => {
  const cacheKey = JSON.stringify(context.params.query)
  
  if (context.method === 'find') {
    const cached = cache.get(cacheKey)
    if (cached && Date.now() - cached.timestamp < 60000) {
      context.result = cached.data
      return context
    }
  }
  
  return context
}

const saveToCache = async (context: HookContext) => {
  if (context.method === 'find') {
    const cacheKey = JSON.stringify(context.params.query)
    cache.set(cacheKey, {
      data: context.result,
      timestamp: Date.now()
    })
  }
  return context
}

// Invalidate cache on mutations
const invalidateCache = async (context: HookContext) => {
  cache.clear()
  return context
}

app.service('users').hooks({
  before: {
    find: [cacheResults]
  },
  after: {
    find: [saveToCache],
    create: [invalidateCache],
    update: [invalidateCache],
    patch: [invalidateCache],
    remove: [invalidateCache]
  }
})

import { hooks, querySyntax, Ajv } from '@feathersjs/schema'

const userSchema = {
  $id: 'User',
  type: 'object',
  additionalProperties: false,
  required: ['email', 'name'],
  properties: {
    id: { type: 'number' },
    email: { type: 'string', format: 'email' },
    name: { type: 'string', minLength: 2 },
    age: { type: 'number', minimum: 0, maximum: 150 }
  }
}

const userValidator = new Ajv().compile(userSchema)

app.service('users').hooks({
  before: {
    create: [hooks.validateData(userValidator)],
    update: [hooks.validateData(userValidator)],
    patch: [hooks.validateData(userValidator)]
  }
})

import { Conflict, BadRequest } from '@feathersjs/errors'
import { HookContext } from '@feathersjs/feathers'

const handleMongoErrors = async (context: HookContext) => {
  const error = context.error as any
  
  if (error.code === 11000) {
    // Duplicate key error
    const field = Object.keys(error.keyPattern)[0]
    throw new Conflict(`Duplicate ${field}`, {
      field,
      value: error.keyValue[field]
    })
  }
  
  if (error.name === 'ValidationError') {
    throw new BadRequest('Validation failed', error.errors)
  }
  
  throw error
}

app.service('users').hooks({
  error: {
    all: [handleMongoErrors]
  }
})

import { MemoryService } from '@feathersjs/memory'
import assert from 'assert'

describe('User Service', () => {
  let service: MemoryService
  
  beforeEach(() => {
    service = new MemoryService({
      paginate: {
        default: 10,
        max: 50
      }
    })
  })
  
  it('creates a user', async () => {
    const user = await service.create({
      name: 'Test User',
      email: '[email protected]'
    })
    
    assert.strictEqual(user.name, 'Test User')
    assert.strictEqual(user.email, '[email protected]')
    assert.ok(user.id)
  })
  
  it('finds users with pagination', async () => {
    await service.create({ name: 'User 1' })
    await service.create({ name: 'User 2' })
    
    const results = await service.find({
      query: { $limit: 1 }
    })
    
    assert.strictEqual(results.total, 2)
    assert.strictEqual(results.data.length, 1)
  })
})