Error Handling

This section explains how to manage business logic errors effectively. For example, if you perform a database call to fetch an item by its ID but the item isn't found, you can return an error message as a structured response.

To streamline this process, we introduced a Result component that simplifies handling success and failure responses.

Result.failure(error) accepts the error type defined in the .error method and sends an error response with a status code of 400.
For successful results, use Result.success(data).

This approach ensures consistency and clarity across your application.

Example

index.ts

import { SchemaValidator, endpoint } from "tarin";
 
// Server initialization
...
 
// Endpoint definition
const getItemByIdEndpoint = endpoint.get("/api/items/:id")
  .input({
    params: SchemaValidator.object({
      id: SchemaValidator.string(),
    }),
  })
  .output({
    body: SchemaValidator.object({
      id: SchemaValidator.string(),
      title: SchemaValidator.string(),
      description: SchemaValidator.string(),
    }),
  })
  .error(SchemaValidator.object({ message: SchemaValidator.string() }))
  .handleLogic((input) => {
    // Input type: { params: { id: string; } }
    // Error type: ({ message: string; }) => void
    // Provides autocompletion and type checking in IDEs like VSCode.
 
    const item = getItemById(input.params.id);
    if (!item) {
      return Result.failure({ message: "Item Not Found" });
    }
 
    // Return the expected type:
    // { body: { id: string; title: string; description: string; } }
    return Result.success({ body: item });
  });
 
tarin.addEndpoints(getItemByIdEndpoint);

Logic Handling API Documentation Generation