- 1. API with NestJS #1. Controllers, routing and the module structure
- 2. API with NestJS #2. Setting up a PostgreSQL database with TypeORM
- 3. API with NestJS #3. Authenticating users with bcrypt, Passport, JWT, and cookies
- 4. API with NestJS #4. Error handling and data validation
- 5. API with NestJS #5. Serializing the response with interceptors
- 6. API with NestJS #6. Looking into dependency injection and modules
- 7. API with NestJS #7. Creating relationships with Postgres and TypeORM
- 8. API with NestJS #8. Writing unit tests
- 9. API with NestJS #9. Testing services and controllers with integration tests
- 10. API with NestJS #10. Uploading public files to Amazon S3
- 11. API with NestJS #11. Managing private files with Amazon S3
- 12. API with NestJS #12. Introduction to Elasticsearch
- 13. API with NestJS #13. Implementing refresh tokens using JWT
- 14. API with NestJS #14. Improving performance of our Postgres database with indexes
- 15. API with NestJS #15. Defining transactions with PostgreSQL and TypeORM
- 16. API with NestJS #16. Using the array data type with PostgreSQL and TypeORM
- 17. API with NestJS #17. Offset and keyset pagination with PostgreSQL and TypeORM
- 18. API with NestJS #18. Exploring the idea of microservices
- 19. API with NestJS #19. Using RabbitMQ to communicate with microservices
- 20. API with NestJS #20. Communicating with microservices using the gRPC framework
- 21. API with NestJS #21. An introduction to CQRS
- 22. API with NestJS #22. Storing JSON with PostgreSQL and TypeORM
- 23. API with NestJS #23. Implementing in-memory cache to increase the performance
- 24. API with NestJS #24. Cache with Redis. Running the app in a Node.js cluster
- 25. API with NestJS #25. Sending scheduled emails with cron and Nodemailer
- 26. API with NestJS #26. Real-time chat with WebSockets
- 27. API with NestJS #27. Introduction to GraphQL. Queries, mutations, and authentication
- 28. API with NestJS #28. Dealing in the N + 1 problem in GraphQL
- 29. API with NestJS #29. Real-time updates with GraphQL subscriptions
- 30. API with NestJS #30. Scalar types in GraphQL
- 31. API with NestJS #31. Two-factor authentication
- 32. API with NestJS #32. Introduction to Prisma with PostgreSQL
- 33. API with NestJS #33. Managing PostgreSQL relationships with Prisma
- 34. API with NestJS #34. Handling CPU-intensive tasks with queues
- 35. API with NestJS #35. Using server-side sessions instead of JSON Web Tokens
- 36. API with NestJS #36. Introduction to Stripe with React
- 37. API with NestJS #37. Using Stripe to save credit cards for future use
- 38. API with NestJS #38. Setting up recurring payments via subscriptions with Stripe
- 39. API with NestJS #39. Reacting to Stripe events with webhooks
- 40. API with NestJS #40. Confirming the email address
- 41. API with NestJS #41. Verifying phone numbers and sending SMS messages with Twilio
- 42. API with NestJS #42. Authenticating users with Google
- 43. API with NestJS #43. Introduction to MongoDB
- 44. API with NestJS #44. Implementing relationships with MongoDB
- 45. API with NestJS #45. Virtual properties with MongoDB and Mongoose
- 46. API with NestJS #46. Managing transactions with MongoDB and Mongoose
- 47. API with NestJS #47. Implementing pagination with MongoDB and Mongoose
- 48. API with NestJS #48. Definining indexes with MongoDB and Mongoose
- 49. API with NestJS #49. Updating with PUT and PATCH with MongoDB and Mongoose
- 50. API with NestJS #50. Introduction to logging with the built-in logger and TypeORM
- 51. API with NestJS #51. Health checks with Terminus and Datadog
- 52. API with NestJS #52. Generating documentation with Compodoc and JSDoc
- 53. API with NestJS #53. Implementing soft deletes with PostgreSQL and TypeORM
- 54. API with NestJS #54. Storing files inside a PostgreSQL database
- 55. API with NestJS #55. Uploading files to the server
- 56. API with NestJS #56. Authorization with roles and claims
- 57. API with NestJS #57. Composing classes with the mixin pattern
- 58. API with NestJS #58. Using ETag to implement cache and save bandwidth
- 59. API with NestJS #59. Introduction to a monorepo with Lerna and Yarn workspaces
- 60. API with NestJS #60. The OpenAPI specification and Swagger
- 61. API with NestJS #61. Dealing with circular dependencies
- 62. API with NestJS #62. Introduction to MikroORM with PostgreSQL
- 63. API with NestJS #63. Relationships with PostgreSQL and MikroORM
- 64. API with NestJS #64. Transactions with PostgreSQL and MikroORM
- 65. API with NestJS #65. Implementing soft deletes using MikroORM and filters
- 66. API with NestJS #66. Improving PostgreSQL performance with indexes using MikroORM
- 67. API with NestJS #67. Migrating to TypeORM 0.3
- 68. API with NestJS #68. Interacting with the application through REPL
- 69. API with NestJS #69. Database migrations with TypeORM
- 70. API with NestJS #70. Defining dynamic modules
- 71. API with NestJS #71. Introduction to feature flags
- 72. API with NestJS #72. Working with PostgreSQL using raw SQL queries
- 73. API with NestJS #73. One-to-one relationships with raw SQL queries
- 74. API with NestJS #74. Designing many-to-one relationships using raw SQL queries
- 75. API with NestJS #75. Many-to-many relationships using raw SQL queries
- 76. API with NestJS #76. Working with transactions using raw SQL queries
- 77. API with NestJS #77. Offset and keyset pagination with raw SQL queries
- 78. API with NestJS #78. Generating statistics using aggregate functions in raw SQL
- 79. API with NestJS #79. Implementing searching with pattern matching and raw SQL
- 80. API with NestJS #80. Updating entities with PUT and PATCH using raw SQL queries
- 81. API with NestJS #81. Soft deletes with raw SQL queries
- 82. API with NestJS #82. Introduction to indexes with raw SQL queries
- 83. API with NestJS #83. Text search with tsvector and raw SQL
- 84. API with NestJS #84. Implementing filtering using subqueries with raw SQL
- 85. API with NestJS #85. Defining constraints with raw SQL
- 86. API with NestJS #86. Logging with the built-in logger when using raw SQL
- 87. API with NestJS #87. Writing unit tests in a project with raw SQL
- 88. API with NestJS #88. Testing a project with raw SQL using integration tests
- 89. API with NestJS #89. Replacing Express with Fastify
- 90. API with NestJS #90. Using various types of SQL joins
- 91. API with NestJS #91. Dockerizing a NestJS API with Docker Compose
- 92. API with NestJS #92. Increasing the developer experience with Docker Compose
- 93. API with NestJS #93. Deploying a NestJS app with Amazon ECS and RDS
- 94. API with NestJS #94. Deploying multiple instances on AWS with a load balancer
- 95. API with NestJS #95. CI/CD with Amazon ECS and GitHub Actions
- 96. API with NestJS #96. Running unit tests with CI/CD and GitHub Actions
- 97. API with NestJS #97. Introduction to managing logs with Amazon CloudWatch
- 98. API with NestJS #98. Health checks with Terminus and Amazon ECS
- 99. API with NestJS #99. Scaling the number of application instances with Amazon ECS
- 100. API with NestJS #100. The HTTPS protocol with Route 53 and AWS Certificate Manager
- 101. API with NestJS #101. Managing sensitive data using the AWS Secrets Manager
- 102. API with NestJS #102. Writing unit tests with Prisma
- 103. API with NestJS #103. Integration tests with Prisma
- 104. API with NestJS #104. Writing transactions with Prisma
- 105. API with NestJS #105. Implementing soft deletes with Prisma and middleware
- 106. API with NestJS #106. Improving performance through indexes with Prisma
- 107. API with NestJS #107. Offset and keyset pagination with Prisma
- 108. API with NestJS #108. Date and time with Prisma and PostgreSQL
- 109. API with NestJS #109. Arrays with PostgreSQL and Prisma
- 110. API with NestJS #110. Managing JSON data with PostgreSQL and Prisma
- 111. API with NestJS #111. Constraints with PostgreSQL and Prisma
- 112. API with NestJS #112. Serializing the response with Prisma
- 113. API with NestJS #113. Logging with Prisma
- 114. API with NestJS #114. Modifying data using PUT and PATCH methods with Prisma
- 115. API with NestJS #115. Database migrations with Prisma
- 116. API with NestJS #116. REST API versioning
- 117. API with NestJS #117. CORS – Cross-Origin Resource Sharing
- 118. API with NestJS #118. Uploading and streaming videos
- 119. API with NestJS #119. Type-safe SQL queries with Kysely and PostgreSQL
- 120. API with NestJS #120. One-to-one relationships with the Kysely query builder
- 121. API with NestJS #121. Many-to-one relationships with PostgreSQL and Kysely
- 122. API with NestJS #122. Many-to-many relationships with Kysely and PostgreSQL
- 123. API with NestJS #123. SQL transactions with Kysely
- 124. API with NestJS #124. Handling SQL constraints with Kysely
- 125. API with NestJS #125. Offset and keyset pagination with Kysely
- 126. API with NestJS #126. Improving the database performance with indexes and Kysely
- 127. API with NestJS #127. Arrays with PostgreSQL and Kysely
- 128. API with NestJS #128. Managing JSON data with PostgreSQL and Kysely
- 129. API with NestJS #129. Implementing soft deletes with SQL and Kysely
- 130. API with NestJS #130. Avoiding storing sensitive information in API logs
- 131. API with NestJS #131. Unit tests with PostgreSQL and Kysely
- 132. API with NestJS #132. Handling date and time in PostgreSQL with Kysely
- 133. API with NestJS #133. Introducing database normalization with PostgreSQL and Prisma
- 134. API with NestJS #134. Aggregating statistics with PostgreSQL and Prisma
- 135. API with NestJS #135. Referential actions and foreign keys in PostgreSQL with Prisma
- 136. API with NestJS #136. Raw SQL queries with Prisma and PostgreSQL range types
- 137. API with NestJS #137. Recursive relationships with Prisma and PostgreSQL
- 138. API with NestJS #138. Filtering records with Prisma
- 139. API with NestJS #139. Using UUID as primary keys with Prisma and PostgreSQL
- 140. API with NestJS #140. Using multiple PostgreSQL schemas with Prisma
- 141. API with NestJS #141. Getting distinct records with Prisma and PostgreSQL
- 142. API with NestJS #142. A video chat with WebRTC and React
- 143. API with NestJS #143. Optimizing queries with views using PostgreSQL and Kysely
- 144. API with NestJS #144. Creating CLI applications with the Nest Commander
- 145. API with NestJS #145. Securing applications with Helmet
- 146. API with NestJS #146. Polymorphic associations with PostgreSQL and Prisma
- 147. API with NestJS #147. The data types to store money with PostgreSQL and Prisma
- 148. API with NestJS #148. Understanding the injection scopes
- 149. API with NestJS #149. Introduction to the Drizzle ORM with PostgreSQL
- 150. API with NestJS #150. One-to-one relationships with the Drizzle ORM
- 151. API with NestJS #151. Implementing many-to-one relationships with Drizzle ORM
- 152. API with NestJS #152. SQL constraints with the Drizzle ORM
- 153. API with NestJS #153. SQL transactions with the Drizzle ORM
- 154. API with NestJS #154. Many-to-many relationships with Drizzle ORM and PostgreSQL
- 155. API with NestJS #155. Offset and keyset pagination with the Drizzle ORM
- 156. API with NestJS #156. Arrays with PostgreSQL and the Drizzle ORM
- 157. API with NestJS #157. Handling JSON data with PostgreSQL and the Drizzle ORM
- 158. API with NestJS #158. Soft deletes with the Drizzle ORM
- 159. API with NestJS #159. Date and time with PostgreSQL and the Drizzle ORM
- 160. API with NestJS #160. Using views with the Drizzle ORM and PostgreSQL
- 161. API with NestJS #161. Generated columns with the Drizzle ORM and PostgreSQL
- 162. API with NestJS #162. Identity columns with the Drizzle ORM and PostgreSQL
- 163. API with NestJS #163. Full-text search with the Drizzle ORM and PostgreSQL
- 164. API with NestJS #164. Improving the performance with indexes using Drizzle ORM
- 165. API with NestJS #165. Time intervals with the Drizzle ORM and PostgreSQL
- 166. API with NestJS #166. Logging with the Drizzle ORM
- 167. API with NestJS #167. Unit tests with the Drizzle ORM
- 168. API with NestJS #168. Integration tests with the Drizzle ORM
- 169. API with NestJS #169. Unique IDs with UUIDs using Drizzle ORM and PostgreSQL
- 170. API with NestJS #170. Polymorphic associations with PostgreSQL and Drizzle ORM
- 171. API with NestJS #171. Recursive relationships with Drizzle ORM and PostgreSQL
- 172. API with NestJS #172. Database normalization with Drizzle ORM and PostgreSQL
- 173. API with NestJS #173. Storing money with Drizzle ORM and PostgreSQL
- 174. API with NestJS #174. Multiple PostgreSQL schemas with Drizzle ORM
- 175. API with NestJS #175. PUT and PATCH requests with PostgreSQL and Drizzle ORM
- 176. API with NestJS #176. Database migrations with the Drizzle ORM
- 177. API with NestJS #177. Response serialization with the Drizzle ORM
In SQL, generated columns automatically calculate their values using data from other fields in the same table. This can help ensure data consistency, improve query performance, and simplify our database design in general. The SQL standard contains two types of generated columns.
Virtual generated columns
With virtual generated columns, we avoid using additional disk storage. Instead, the database calculates their value on demand, for example, during a SELECT query. However, PostgreSQL currently lacks support for the virtual generated columns.
Stored generated columns
The stored generated columns use storage like regular ones. However, PostgreSQL updates their values only when the row is modified, not every time they’re requested.
To create a stored generated column with the Drizzle ORM, we must use the generatedAlwaysAs function. It makes a lot of sense to refer to other columns while defining a generated column.
However, a generated column can’t refer to other generated columns.
database-schema.ts
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import { serial, text, pgTable } from 'drizzle-orm/pg-core'; import { SQL, sql } from 'drizzle-orm'; // ... export const users = pgTable('users', { id: serial('id').primaryKey(), email: text('email').unique().notNull(), first_name: text('name').notNull(), last_name: text('name').notNull(), fullName: text('full_name').generatedAlwaysAs( (): SQL => sql`${users.first_name} || ' ' || ${users.last_name}`, ), }); export const databaseSchema = { users, // ... }; |
In the above example, we defined the full_name column as a combination of the first_name and the last_name. Let’s test it by inserting a row.
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INSERT INTO users( email, first_name, last_name ) VALUES ( 'marcin@wanago.io', 'Marcin', 'Wanago' ); |
As we can see above, PostgreSQL automatically filled the value of the full_name column.
Working with numbers
Besides operating on text, we can work with numbers as well.
database-schema.ts
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import { serial, pgTable, numeric } from 'drizzle-orm/pg-core'; import { SQL, sql } from 'drizzle-orm'; export const routes = pgTable('routes', { id: serial('id').primaryKey(), distanceInKilometers: numeric('distance_in_kilometers').notNull(), distanceInMiles: numeric('distance_in_miles').generatedAlwaysAs( (): SQL => sql`${routes.distanceInKilometers} / 1.609344`, ), }); // ... export const databaseSchema = { routes, }; |
Using SQL functions
We can also use SQL functions, but they need to be immutable. An immutable function does not modify the database and always returns the same result given the same arguments.
database-schema.ts
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import { serial, text, pgTable, numeric } from 'drizzle-orm/pg-core'; import { SQL, sql } from 'drizzle-orm'; export const articles = pgTable('articles', { id: serial('id').primaryKey(), title: text('title').notNull(), paragraphs: text('paragraphs').array().notNull(), paragraphs_number: numeric('paragraphs_number').generatedAlwaysAs( (): SQL => sql`array_length(${articles.paragraphs}, 1)`, ), }); // ... export const databaseSchema = { articles, // ... }; |
In the first example in this article, we combined the first_name and last_name columns using the || operator. Instead, we might think about using the concat function built into PostgreSQL.
database-schema.ts
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import { serial, text, pgTable } from 'drizzle-orm/pg-core'; import { SQL, sql } from 'drizzle-orm'; // ... export const users = pgTable('users', { id: serial('id').primaryKey(), email: text('email').unique().notNull(), first_name: text('name').notNull(), last_name: text('name').notNull(), fullName: text('full_name').generatedAlwaysAs( (): SQL => sql`concat(${users.first_name}, ' ', ${users.last_name})`, ), }); export const databaseSchema = { users, // ... }; |
Unfortunately, the concat function is not immutable. Surprisingly, it can give us different results based on the configuration of our database.
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SET TIME ZONE 'UTC'; -- Returns "Current time: 2021-11-25 22:08:00.041641" SELECT CONCAT('Current time: ', NOW()::TIMESTAMP); SET TIME ZONE 'UTC+1'; -- Returns "Current time: 2021-11-25 21:08:00.041641" SELECT CONCAT('Current time: ', NOW()::TIMESTAMP); |
If you want to know more about timezones, check outAPI with NestJS #159. Date and time with PostgreSQL and the Drizzle ORM
Type-safety in Drizzle ORM
Thanks to how Drizzle ORM is written, TypeScript stops us if we try to insert a row while providing an explicit value for a generated column.
users.service.ts
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import { Injectable } from '@nestjs/common'; import { UserDto } from './user.dto'; import { DrizzleService } from '../database/drizzle.service'; import { databaseSchema } from '../database/database-schema'; @Injectable() export class UsersService { constructor(private readonly drizzleService: DrizzleService) {} async create(user: UserDto) { const createdUsers = await this.drizzleService.db .insert(databaseSchema.users) .values({ firstName: user.firstName, lastName: user.lastName, email: user.email, password: user.password, fullName: `${user.firstName} ${user.lastName}`, }) .returning(); return createdUsers.pop(); } // ... } |
When we try the above code, we see the “No overload matches this call” error.
Simulating virtual generated columns
Although PostgreSQL does not natively support virtual generated columns, we can simulate this functionality in NestJS by serializing the data we send in our HTTP responses. One way to do that would be with the class-transformer library.
user-response.dto.ts
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import { Expose, Transform } from 'class-transformer'; export class UserResponseDto { id: number; firstName: string; lastName: string; @Expose() @Transform(({ obj }) => { return `${obj.firstName} ${obj.lastName}`; }) fullName: string; } |
The most straightforward way to create an instance of the UserResponseDto class is to use the @TransformPlainToInstance() decorator built into the class-transformer library.
users.controller.ts
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import { Body, Controller, HttpCode, Post, Res } from '@nestjs/common'; import { AuthenticationService } from './authentication.service'; import { LogInDto } from './dto/log-in.dto'; import { Response } from 'express'; import { TransformPlainToInstance } from 'class-transformer'; import { UserResponseDto } from '../users/user-response.dto'; @Controller('authentication') export class AuthenticationController { constructor(private readonly authenticationService: AuthenticationService) {} @HttpCode(200) @Post('log-in') @TransformPlainToInstance(UserResponseDto) async logIn( @Body() logInData: LogInDto, @Res({ passthrough: true }) response: Response, ) { const user = await this.authenticationService.getAuthenticatedUser(logInData); const cookie = this.authenticationService.getCookieWithJwtToken(user.id); response.setHeader('Set-Cookie', cookie); return user; } // ... } |
With this approach, the database does not store the fullName value in a column. Instead, it calculates it on the fly every time a user makes the HTTP request. We must remember, though, that PostgreSQL won’t know about the fullName field in this approach. Therefore, we can’t use it in any SQL queries.
Summary
Generated columns can be helpful if we frequently perform certain operations on our data. By storing the results ahead of time, we can improve our application’s performance. However, it’s important to note that this optimization can come at the expense of slower INSERT and UPDATE operations.
Generated columns can also be used when we refactor our database. If we need to modify some columns while maintaining backward compatibility, generated columns can help. All of the above make generated columns a feature worth knowing, particularly now that the Drizzle ORM has recently introduced support for them in PostgreSQL.