PostgreSQL to Typescript Type Mapping

TypeScript has gained significant popularity due to its ability to add strong typing and compile-time error checking to JavaScript. When building applications that interact with databases, developers often face the challenge of mapping database types to TypeScript types. PostgreSQL, being a powerful and feature-rich open-source database, is widely used in many projects. In this article, we will explore how PostgreSQL to TypeScript Type Mapping, enabling seamless integration between the database and TypeScript applications.

Understanding PostgreSQL Types:

PostgreSQL provides a rich set of data types, including basic types like integers, strings, and booleans, as well as advanced types like arrays, JSON, and geometric types. When mapping these types to TypeScript, it’s essential to find suitable equivalents that preserve the semantic meaning and ensure type safety.

TypeScript Type Mapping:

1. Basic Types:

Let’s start with the basic types in PostgreSQL:

• integer and bigint: These can be mapped to TypeScript’s number
• text, varchar, and char: These can be mapped to TypeScript’s string
• boolean: This maps directly to TypeScript’s boolean
• numeric and decimal: These can be mapped to TypeScript’s number type or a custom TypeScript type that handles decimal precision, depending on the application’s requirements.
• timestamp and timestamptz: These can be mapped to TypeScript’s Date

2. Advanced Types:

• array: PostgreSQL supports arrays of any data type. TypeScript’s array notation ([]) can be used to represent arrays of basic types. For example, an integer[] in PostgreSQL can be mapped to number[] in TypeScript.
• json and jsonb: These types can be mapped to TypeScript’s object type or a custom TypeScript interface that represents the JSON structure.
• enum: In PostgreSQL, an enum type represents a predefined set of values. TypeScript provides support for enums, making it easy to map PostgreSQL enums to TypeScript enums.

3. Custom Types:

PostgreSQL allows defining custom types using the CREATE TYPE statement. When mapping custom types to TypeScript, developers can create corresponding TypeScript types or interfaces that mirror the structure and semantics of the custom types.

Mapping Strategies and Libraries:

While it is possible to manually define type mappings between PostgreSQL and TypeScript, using existing tools and libraries can significantly simplify the process. Here are a few options:

• TypeORM: TypeORM is a popular Object-Relational Mapping (ORM) library for TypeScript and JavaScript. It provides a powerful entity modeling system that automatically maps database tables and columns to TypeScript classes and properties. TypeORM supports PostgreSQL and offers various decorators and type annotations for defining type mappings.
• pgTyped: pgTyped is a TypeScript-first library that aims to provide type-safe query generation for PostgreSQL. It generates TypeScript types based on SQL queries, allowing developers to write type-safe queries directly in TypeScript code. pgTyped leverages TypeScript’s type inference capabilities and provides a seamless integration with PostgreSQL.

Mapping PostgreSQL types to TypeScript types is an essential aspect of building robust and type-safe database integrations in TypeScript applications. By understanding the semantics of PostgreSQL types and leveraging suitable mapping strategies and libraries like TypeORM and pgTyped, developers can simplify the process and ensure type safety throughout their applications. With the ability to seamlessly interact with PostgreSQL, TypeScript developers can build scalable and maintainable applications with confidence.