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Layerfig Layerfig

Custom Parser

The library provides abstractions to support common configuration file extensions. However, you may need to parse a file type that isn’t supported out-of-the-box.

To do so, you can write a custom parser using the defineConfigParser utility function.

Its API is minimal and straightforward:

./path/to/custom-parser.ts
import { defineConfigParser } from "@layerfig/config";


export const customParser = defineConfigParser({
  acceptedFileExtensions: ["ini"],
  parse: (fileContent) => {
    // Logic to fetch, read, and parse the content
  },
});

The parse function must return an object that conforms to the Result type:

const successResult = {
  ok: true,
  data: {}, // The object containing your parsed configuration
};


const errorResult = {
  ok: false,
  error: new Error("Some error"), // The error that occurred
};

Then, use your custom parser by passing it to the ConfigBuilder:

import { ConfigBuilder } from "@layerfig/config";
import { customParser } from "./path/to/custom-parser";


export const config = new ConfigBuilder({
  validate: (finalConfig, z) => {
    const schema = z.object({
      appURL: z.url(),
      port: z.number(),
    });


    return schema.parse(finalConfig)
  },
  parser: customParser,
})
  .addSource("base.ini")
  .addSource("live.ini")
  .build();