igniter-procedures

Igniter.js: Procedures and Context

This guide covers two core concepts in Igniter.js: the Context system for dependency injection and Procedures for creating reusable middleware.

1. The Context System

The Context is a type-safe dependency injection mechanism that makes global services and request-specific data available throughout your API layer.

1.1. Base Context

The base context defines services that are available in every request handler. It is defined once when you initialize the Igniter instance.

• File Location: src/igniter.context.ts
• Purpose: To provide singleton services like database clients, loggers, and other providers to your actions and procedures.

// src/igniter.context.ts
export function createContext() {
  return {
    database: prisma, // Prisma client instance
    // ... other global services
  };
}

export type IgniterAppContext = ReturnType<typeof createContext>;

// src/igniter.ts
export const igniter = Igniter
  .context<IgniterAppContext>()
  // ... rest of the configuration
  .create();

Inside any action handler, you can now access context.database in a fully type-safe way.

1.2. Dynamic Context Extension

The real power of the context comes from its ability to be dynamically extended on a per-request basis. Procedures are the mechanism for this.

When a procedure returns a value, that value is deeply merged into the context object, making it available to all subsequent procedures and the final action handler. This process is fully type-safe.

2. Procedures (igniter.procedure)

A Procedure is a piece of reusable logic that runs before your main action handler. It is the Igniter.js equivalent of middleware. Procedures are ideal for handling cross-cutting concerns like authentication, logging, or data transformation.

2.1. Creating a Simple Procedure

A procedure is a function that receives the handler context and can perform actions. If it returns an object, that object is merged into the main context.