Readme

Upkeep

Upkeep is a function for lazily ensuring that data is migrated to the latest version.

Usage

import { upkeep } from "./object.upkeep";

/**
 * The data to migrate, if a value is passed in.
 */
const data = {
  /* your data object */
};

/**
 * The version to migrate from, if a value is passed in.
 */
const version = "1";

/**
 * The migrations to run, if a value is passed in.
 * A Map object where the key is the version and the value is a function that performs the migration on the data.
 */
const migrations = new Map<string, (data: any) => any>();
migrations.set("1", (data) => {
  /* migration logic for version 1 */
});
migrations.set("2", (data) => {
  /* migration logic for version 2 */
});

const [migratedData, migratedVersion] = upkeep({
  data,
  version,
  migrations,
});

API

upkeep

The upkeep function takes an object as its argument with the following properties:

• data (optional): The data to migrate, if a value is passed in.
• version (optional): The version to migrate from, if a value is passed in.
• migrations: The migrations to run, specified as a Map object where the key is the version and the value is a function that performs the migration on the data.

The upkeep function returns an array with two elements:

• migratedData: The migrated data after applying the necessary migrations.
• migratedVersion: The version of the data after migration.

Examples

Throws if no migrations are provided

import { upkeep } from "./object.upkeep";

try {
  upkeep({});
} catch (error) {
  console.error(error);
}

Returns defaults if only one migration given

import { upkeep } from "./object.upkeep";

const migrations = new Map();
migrations.set("1", () => ({ test: "test" }));

const [data, version] = upkeep({
  migrations,
});

console.log(data); // { test: "test" }
console.log(version); // "1"

Only applies first migration if version is missing

import { upkeep } from "./object.upkeep";

const migrations = new Map();
migrations.set("1", () => ({ test: "test" }));

const [data, version] = upkeep({
  migrations,
  version: "1",
  data: { test: "i've already been set!" },
});

console.log(data); // { test: "i've already been set!" }
console.log(version); // "1"

Throws if version is not in list of migrations

import { upkeep } from "./object.upkeep";

const migrations = new Map();
migrations.set("1", () => ({ test: "test" }));

try {
  upkeep({
    migrations,
    version: "2",
  });
} catch (error) {
  console.error(error);
}

Applies only needed migrations

import { upkeep } from "./object.upkeep";

const migrations = new Map();
migrations.set("1", () => ({ test: "test" }));
migrations.set("2", (data) => ({ ...data, test2: "test2" }));

const [data, version] = upkeep<{
  test: string;
  test2: string;
}>({
  migrations,
  version: "1",
  data: { test: "i've already been set!" },
});

console.log(data); // { test: "i've already been set!", test2: "test2" }
console.log(version); // "2"

License

This project is licensed under the MIT License - see the LICENSE file for details.