- 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
When working with SQL databases, we can configure constraints to ensure our data does not get corrupted. In this article, we explore and implement different SQL constraints using PostgreSQL, NestJS, and the Drizzle ORM.
Not-null constraint
By default, SQL columns can hold nulls, representing an absence of value. We need the not-null constraint using the notNull() function to prevent that.
database-schema.ts
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export const articles = pgTable('articles', { id: serial('id').primaryKey(), title: text('title').notNull(), content: text('content').notNull(), authorId: integer('author_id') .references(() => users.id) .notNull(), }); // ... |
Not-null error handling
Thanks to adding the not-null constraint, the database now throws an error when we try to save a null value into the database. PostgreSQL uses the 23502 error code. To avoid having to remember it, let’s create an enum to store error codes.
postgres-error-code.enum.ts
1 2 3 |
export enum PostgresErrorCode { NotNullViolation = '23502', } |
In TypeScript, all caught errors are initially of the unknown type. Let’s create an interface and a type guard to deal with that.
database-error.ts
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import { PostgresErrorCode } from './postgres-error-code.enum'; import { isRecord } from '../utilities/is-record'; export interface DatabaseError { code: PostgresErrorCode; detail: string; table: string; column?: string; } export function isDatabaseError(value: unknown): value is DatabaseError { if (!isRecord(value)) { return false; } const { code, detail, table } = value; return Boolean(code && detail && table); } |
If you want to know more about type guards, check out Structural type system and polymorphism in TypeScript. Type guards with predicates
The isRecord function checks if a particular value is of the Record<string, unknown> type.
Using the isDatabaseError function, we can check if a particular error matches the DatabaseError interface.
articles.service.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 |
import { BadRequestException, Injectable, } from '@nestjs/common'; import { DrizzleService } from '../database/drizzle.service'; import { databaseSchema } from '../database/database-schema'; import { CreateArticleDto } from './dto/create-article.dto'; import { isDatabaseError } from '../database/databse-error'; import { PostgresErrorCode } from '../database/postgres-error-code.enum'; @Injectable() export class ArticlesService { constructor(private readonly drizzleService: DrizzleService) {} async create(article: CreateArticleDto, authorId: number) { try { const createdArticles = await this.drizzleService.db .insert(databaseSchema.articles) .values({ authorId, title: article.title, content: article.content, }) .returning(); return createdArticles.pop(); } catch (error) { if ( isDatabaseError(error) && error.code === PostgresErrorCode.NotNullViolation ) { throw new BadRequestException( `The value of ${error.column} can not be null`, ); } throw error; } } // ... } |
If we don’t recognize the error, we want to re-throw it to make sure the exception is properly propagated and not ignored.
Unique constraint
Using the unique constraint, we can ensure that all values in a certain column are unique across the entire table. A great example is the email column in the users table. Thanks to the unique constraint, we ensure that no users share the same email.
database-schema.ts
1 2 3 4 5 6 7 8 9 |
import { serial, text, pgTable } from 'drizzle-orm/pg-core'; export const users = pgTable('users', { id: serial('id').primaryKey(), email: text('email').unique().notNull(), // ... }); // ... |
Using the unique() function, we tell Drizzle ORM to add the unique constraint. Because of that, PostgreSQL will throw an error when we try to create two users with the same email.
Unique constraint error handling
To handle the violation of the unique constraint, we should start by adding the 23505 error code to our enum.
postgres-error-code.enum.ts
1 2 3 4 |
export enum PostgresErrorCode { UniqueViolation = '23505', NotNullViolation = '23502', } |
We can now use it in our service to respond with a custom exception if someone tries to use an occupied email address.
users.service.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 |
import { Injectable } from '@nestjs/common'; import { UserDto } from './user.dto'; import { DrizzleService } from '../database/drizzle.service'; import { databaseSchema } from '../database/database-schema'; import { PostgresErrorCode } from '../database/postgres-error-code.enum'; import { UserAlreadyExistsException } from './user-already-exists.exception'; import { isDatabaseError } from '../database/databse-error'; @Injectable() export class UsersService { constructor(private readonly drizzleService: DrizzleService) {} async create(user: UserDto) { try { const createdUsers = await this.drizzleService.db .insert(databaseSchema.users) .values(user) .returning(); return createdUsers.pop(); } catch (error) { if ( isDatabaseError(error) && error.code === PostgresErrorCode.UniqueViolation ) { throw new UserAlreadyExistsException(user.email); } throw error; } } // ... } |
Primary key constraint
When we add a primary key constraint, we choose a particular column to be a unique identifier for the rows in the table.
database-schema.ts
1 2 3 4 5 6 7 8 |
import { serial, pgTable } from 'drizzle-orm/pg-core'; export const addresses = pgTable('addresses', { id: serial('id').primaryKey(), // ... }); // ... |
Primary key constraint error handling
In most cases, we won’t have a chance to violate the primary key constraint because we usually let PostgreSQL generate the key for us. An example where that might not be the case is when dealing with many-to-many relationships.
Under the hood, the primary key constraint consists of the not-null and unique constraints. To implement error handling for the primary key constraint, you should look for the not-null and unique constraint violations.
Foreign key constraint
We use the foreign key constraint to define relationships. It ensures that a value in one table’s column matches a value in another table’s column.
database-schema.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 |
import { serial, text, integer, pgTable } from 'drizzle-orm/pg-core'; export const users = pgTable('users', { id: serial('id').primaryKey(), email: text('email').unique().notNull(), // ... }); export const articles = pgTable('articles', { id: serial('id').primaryKey(), title: text('title').notNull(), content: text('content').notNull(), authorId: integer('author_id') .references(() => users.id) .notNull(), }); // ... |
Foreign constraint error handling
A good example of when the above constraint might cause an error is when we try to delete a user who is the author of at least one article. To handle that, we first need to adjust our enum.
postgres-error-code.enum.ts
1 2 3 4 5 |
export enum PostgresErrorCode { UniqueViolation = '23505', NotNullViolation = '23502', ForeignKeyViolation = '23503', } |
We can now use it to handle the foreign constraint violation.
users.service.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 |
import { BadRequestException, Injectable, NotFoundException, } from '@nestjs/common'; import { DrizzleService } from '../database/drizzle.service'; import { databaseSchema } from '../database/database-schema'; import { eq } from 'drizzle-orm'; import { PostgresErrorCode } from '../database/postgres-error-code.enum'; import { isDatabaseError } from '../database/databse-error'; @Injectable() export class UsersService { constructor(private readonly drizzleService: DrizzleService) {} // ... async delete(userId: number) { try { const deletedUsers = await this.drizzleService.db .delete(databaseSchema.users) .where(eq(databaseSchema.users.id, userId)) .returning(); if (deletedUsers.length === 0) { throw new NotFoundException(); } } catch (error) { if ( isDatabaseError(error) && error.code === PostgresErrorCode.ForeignKeyViolation ) { throw new BadRequestException( 'Can not remove a user that is an author of an article', ); } throw error; } } } |
Check constraint
We can use the check constraint to specify a particular column’s requirements more generically. Unfortunately, Drizzle Kit does not support it out of the box yet. To add it, we need to create a custom migration.
1 |
npx drizzle-kit generate --custom --name add-articles-title-check |
Now, we need to write a SQL migration that adds the constraint manually. Let’s ensure that the title of each article is not an empty string.
0003_add-articles-title-check.sql
1 |
ALTER TABLE "articles" ADD CHECK(length(title) > 0); |
We can now apply it using the migrate command.
1 |
npx drizzle-kit migrate |
Check constraint error handling
Let’s start by adding the check constraint violation to our enum.
postgres-error-code.enum.ts
1 2 3 4 5 6 |
export enum PostgresErrorCode { UniqueViolation = '23505', NotNullViolation = '23502', ForeignKeyViolation = '23503', CheckViolation = '23514', } |
We can now use the enum to handle the check constraint violation.
articles.service.ts
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 |
import { BadRequestException, Injectable, } from '@nestjs/common'; import { DrizzleService } from '../database/drizzle.service'; import { databaseSchema } from '../database/database-schema'; import { CreateArticleDto } from './dto/create-article.dto'; import { isDatabaseError } from '../database/databse-error'; import { PostgresErrorCode } from '../database/postgres-error-code.enum'; @Injectable() export class ArticlesService { constructor(private readonly drizzleService: DrizzleService) {} async create(article: CreateArticleDto, authorId: number) { try { const createdArticles = await this.drizzleService.db .insert(databaseSchema.articles) .values({ authorId, title: article.title, content: article.content, }) .returning(); return createdArticles.pop(); } catch (error) { if (!isDatabaseError(error)) { throw error; } if (error.code === PostgresErrorCode.NotNullViolation) { throw new BadRequestException( `The value of ${error.column} can not be null`, ); } if (error.code === PostgresErrorCode.CheckViolation) { throw new BadRequestException('The title can not be an empty string'); } throw error; } } // ... } |
Summary
In this article, we’ve gone through various constraints PostgreSQL offers and implemented them using the Drizzle ORM. We also learned how to implement constraint violation handling in a NestJS application that uses Drizzle. Thanks to that, we can now better care for the integrity of the data in our database.