- 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
One of the most important aspects of working with a database is ensuring the stored information is correct. One of the fundamental ways of doing that is by using the correct data types for the columns in our tables. Thanks to that, we can make sure that a particular column holds only numbers, for example. In this article, we learn to use constraints to have even more control over our data and reject it when it does not match our guidelines. Doing that on the database level can ensure the integrity of the data to a greater extent than doing that through our TypeScript code.
Primary key
A primary key is a unique identifier for rows in the table. Therefore, all values in the column marked as a primary key need to be unique. Also, they can’t be null.
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CREATE TABLE posts ( id integer PRIMARY KEY ) |
It is common to use the serial type when creating primary keys. Under the hood, PostgreSQL creates an integer column that auto increments every time we add a new row to the table.
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CREATE TABLE posts ( id serial PRIMARY KEY ) |
Right now it is recommended to use identity columns instead of the serial type with PostgreSQL. If you want to know more, check out this article.
Unfortunately, Prisma does not support that out of the box yet.
To achieve the above with Prisma, we need to create an integer property. By marking it with @id, we make it a primary key. To ensure PostgreSQL generates the value for the id automatically, we need to use @default(autoincrement()).
postSchema.prisma
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model Post { id Int @id @default(autoincrement()) // ... } |
Using multiple columns
While we usually use a single column as the primary key, it can consist of multiple columns.
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CREATE TABLE users ( first_name text, last_name text, PRIMARY KEY (first_name, last_name) ) |
In the above code, we create a primary key that consists of both the first_name and last_name. Since PostgreSQL enforces primary keys to be unique, we can’t have two users sharing the same combination of first and last names. Therefore, it would be better to use a separate id column.
Primary keys consisting of multiple columns are popular when working with many-to-many relationships. If you want to know more, check out API with NestJS #75. Many-to-many relationships using raw SQL queries
To create a composite primary key with Prisma, we need the @@id attribute.
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model User { firstName String secondName String @@id([firstName, secondName]) } |
Unique
By using the unique constraint, we can force the values in a particular column to be unique across all of the rows in a specific table.
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CREATE TABLE users ( id serial PRIMARY KEY, email text UNIQUE ) |
Thanks to the above, we require each user to have a unique email. To do that with Prisma, we need the @unique keyword.
userSchema.prisma
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model User { id Int @id @default(autoincrement()) email String @unique } |
We can also ensure that a group of columns have a unique value. To do that with SQL, we need a slightly different syntax.
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CREATE TABLE users ( id serial PRIMARY KEY, first_name text, last_name text, UNIQUE (first_name, last_name) ) |
Through the above code, we expect the users to have a unique combination of the first and last names. To achieve that with Prisma, we need the @@unique keyword.
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model User { id Int @id @default(autoincrement()) firstName String secondName String @@unique([firstName, secondName]) } |
Unique constraint violation
An essential part of defining constraints is handling the case when they are not complied with. Prisma has a set of codes that describe the error that occurred. Let’s start creating an enum that holds them.
prismaError.ts
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export enum PrismaError { RecordDoesNotExist = 'P2025', } |
We now need to use the try...catch statement whenever we perform an operation that might fail. We also should check if the error that occurred is an instance of the Prisma.PrismaClientKnownRequestError class.
authentication.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 { HttpException, HttpStatus, Injectable } from '@nestjs/common'; import { UsersService } from '../users/users.service'; import RegisterDto from './dto/register.dto'; import * as bcrypt from 'bcrypt'; import { PrismaError } from '../utils/prismaError'; import { Prisma } from '@prisma/client'; @Injectable() export class AuthenticationService { constructor(private readonly usersService: UsersService) {} public async register(registrationData: RegisterDto) { const hashedPassword = await bcrypt.hash(registrationData.password, 10); try { const createdUser = await this.usersService.create({ ...registrationData, password: hashedPassword, }); return { ...createdUser, password: undefined, }; } catch (error) { if ( error instanceof Prisma.PrismaClientKnownRequestError && error?.code === PrismaError.UniqueConstraintFailed ) { throw new HttpException( 'User with that email already exists', HttpStatus.BAD_REQUEST, ); } throw new HttpException( 'Something went wrong', HttpStatus.INTERNAL_SERVER_ERROR, ); } } // ... } |
Not null
With the not-null constraint, we enforce a column to have a value other than null.
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CREATE TABLE posts ( id serial PRIMARY KEY, title text NOT NULL ) |
The official PostgreSQL documentation states that in most database designs, most columns should be marked as non-nullable. Prisma embraces that approach by making all columns non-nullable by default.
If we want to make a particular column nullable with Prisma, we need to add the question mark.
postSchema.prisma.ts
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model Post { id Int @id @default(autoincrement()) title String scheduledDate DateTime? @db.Timestamptz } |
If you want to know how to handle dates with Prisma, check out API with NestJS #108. Date and time with Prisma and PostgreSQL
A reliable approach to avoiding the null constraint violation is validating the data provided by the users through our API. A common way of doing that with NestJS is using the class-validator library.
createPost.dto.ts
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import { IsString, IsNotEmpty, IsNumber, IsOptional, IsISO8601, } from 'class-validator'; export class CreatePostDto { @IsString() @IsNotEmpty() title: string; @IsString({ each: true }) @IsNotEmpty() paragraphs: string[]; @IsOptional() @IsNumber({}, { each: true }) categoryIds?: number[]; @IsISO8601({ strict: true, }) @IsOptional() scheduledDate?: string; } |
When using the above validation, it is also important to use the ValidationPipe provided by NestJS.
main.ts
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import { NestFactory } from '@nestjs/core'; import { AppModule } from './app.module'; import { ValidationPipe } from '@nestjs/common'; import * as cookieParser from 'cookie-parser'; async function bootstrap() { const app = await NestFactory.create(AppModule); app.use(cookieParser()); app.useGlobalPipes( new ValidationPipe({ transform: true, }), ); await app.listen(3000); } bootstrap(); |
Foreign key
By using the foreign key constraint, we ensure that the values from one column match values from another table. We use this when defining relationships.
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CREATE TABLE users ( id serial PRIMARY KEY ); CREATE TABLE posts ( id serial PRIMARY KEY, author_id integer REFERENCES users(id) ); |
By using the REFERENCES keyword, we define a foreign key. In the above example, each post needs to refer to an existing user.
Creating a relationship such as the one above using Prisma is straightforward.
userSchema.prisma
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model User { id Int @id @default(autoincrement()) email String @unique posts Post[] } |
postSchema.prisma
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model Post { id Int @id @default(autoincrement()) title String paragraphs String[] author User @relation(fields: [authorId], references: [id]) } |
However, relationships are a broad topic and deserve a separate article. To know more, check out API with NestJS #33. Managing PostgreSQL relationships with Prisma.
Check
The check constraint is the most constraint available in PostgreSQL. Using it, we can define the requirements for the value in a particular column.
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CREATE TABLE products ( id serial PRIMARY KEY, price numeric CHECK (price > 0) ) |
The check constraint can also use multiple columns.
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CREATE TABLE events ( id serial PRIMARY KEY, start_date timestamptz, end_date timestamptz, CHECK (start_date < end_date) ) |
Unfortunately, Prisma does not support check constraints currently. To deal with this problem, we can create a custom migration with raw SQL.
First, let’s add the price property to our Product schema.
product.prisma
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model Product { id Int @id @default(autoincrement()) name String properties Json? @db.JsonB price Int @default(0) } |
Now, let’s generate a migration.
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npx prisma migrate dev --name product-price |
Doing the above generated a new migration.
20230604193023_product_price/migration.sql
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-- AlterTable ALTER TABLE "Product" ADD COLUMN "price" INTEGER NOT NULL DEFAULT 0; |
Let’s modify the generated file to include the check constraint.
20230604193023_product_price/migration.sql
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-- AlterTable ALTER TABLE "Product" ADD COLUMN "price" INTEGER NOT NULL DEFAULT 0; ALTER TABLE "Product" ADD CHECK(price > 0); |
By doing the above, we add the check constraint even when Prisma does not support it yet.
Handling the check error violation
Since Prisma does not support the check constraint, it does not handle its violation very well, either. To catch this error, we need to use the Prisma.PrismaClientUnknownRequestError class.
products.service.ts
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import { BadRequestException, Injectable } from '@nestjs/common'; import CreateProductDto from './dto/createProduct.dto'; import { PrismaService } from '../prisma/prisma.service'; import { Prisma } from '@prisma/client'; @Injectable() export default class ProductsService { constructor(private readonly prismaService: PrismaService) {} async createProduct(product: CreateProductDto) { try { return await this.prismaService.product.create({ data: product, }); } catch (error) { if ( error instanceof Prisma.PrismaClientUnknownRequestError && error.message.includes('check constraint') ) { throw new BadRequestException(); } throw error; } } // ... } |
However, in our particular case, validating the price value through the class-validator library makes sense.
createProduct.dto.ts
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import { Prisma } from '@prisma/client'; import { IsString, IsNotEmpty, IsOptional, IsNumber, IsPositive } from 'class-validator'; import IsJsonObject from '../../utils/isJsonObject'; export class CreateProductDto { @IsString() @IsNotEmpty() name: string; @IsJsonObject() @IsOptional() properties?: Prisma.InputJsonObject; @IsNumber() @IsPositive() price: number; } export default CreateProductDto; |
Thanks to the above, trying to send a POST request would result in a “400 Bad Request” if the price is not a positive number.
Summary
In this article, we’ve gone through various constraints supported by PostgreSQL. We’ve learned how to use them both through raw SQL and Prisma. Learning SQL proves helpful, especially in the case of the check constraint that Prisma does not yet support. Fortunately, we managed to overcome this problem by writing a migration manually. Learning all of the above helped us have more control over the data saved in our database.