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Learnings

Types as sets of values

keyof with union (|) and intersection (&)

There are no keys that TypeScript can guarantee belong to a value in the union type, so keyof for the union must be the empty set (never). Or, more formally:

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REVOKE ALL ON DATABASE example_database FROM example_user;
GRANT CONNECT ON DATABASE example_database TO example_user;
GRANT SELECT ON ALL TABLES IN SCHEMA public TO example_user;
ALTER DEFAULT PRIVILEGES IN SCHEMA public GRANT SELECT ON TABLES TO example_user;

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import { PrismaClient } from '@prisma/client'

export const prisma = new PrismaClient()

export function createContext() {
  return { prisma }
}

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Useful linux commands

• List files recursively: find input/ -type f | wc -l

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http POST https://graphqlapi.now.sh query="query { feed { id title } }"

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select * from pg_stat_activity where datname = 'DB_NAME'

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# by default, the Ghost image will use SQLite (and thus requires no separate database container)
# we have used MySQL here merely for demonstration purposes (especially environment-variable-based configuration)

version: '3.1'

services:

  ghost:
    image: ghost:3-alpine
    restart: always

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import csv
import tweepy

# get credentials at developer.twitter.com
auth = tweepy.OAuthHandler('API Key', 'API Secret')
auth.set_access_token('Access Token', 'Access Token Secret')


api = tweepy.API(auth)

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# curl https://codeload.github.com/ORG/REPO/tar.gz/BRANCH
# tar -xz --strip=3 REPO-BRANCH/deployment-platforms/zeit-now/
curl https://codeload.github.com/prisma/prisma-examples/tar.gz/prisma2-deployment-zeit | tar -xz --strip=3 prisma-examples-prisma2-deployment-zeit/deployment-platforms/zeit-now/

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ORM Patterns

In practice there are two common ORM patterns:

• ActiveRecord: uses the model class to handle both business logic and database access.
• DataMapper: a more complex approach which separates the in-memory objects from the database. Uses two class types:
  • Mapper: handles database access and mapping entities
  • Entities: in-memory representation with business logic

Some ORMs, like TypeORM support both patterns. Others like Sequelize support only ActiveRecord.