A library for applying migrations to localstorage.
npm install localstorage-migratorThis is a library for handling migrations of local storage. It is similar to DbUp.
It uses rstolsmark-json-migrator for handling the migration logic.
``bash`
npm i localstorage-migrator
A migration is an object that consist of two items:
- name: This has to be unique
- up: a method that is called when applying the migration.
Example:
`typescript
import * as migrator from "localstorage-migrator";
const objectKey = "someKey";
const migrations = [
{
name: "delta1",
up: () => {
localStorage.setItem(
objectKey,
JSON.stringify({
name: "John Doe"
})
);
}
},
{
name: "delta2",
up: () => {
var object = JSON.parse(localStorage.getItem(objectKey) as string);
object.age = 2;
localStorage.setItem(objectKey, JSON.stringify(object));
}
},
{
name: "delta3",
up: () => {
var object = JSON.parse(localStorage.getItem(objectKey) as string);
object.age++;
localStorage.setItem(objectKey, JSON.stringify(object));
}
}
];
/* This would typically be called in some startup method
before local storage is accessed by other code. */
export function runMigrations(): void {
migrator.migrate(migrations);
}
``
An example project can be found on GitHub:
https://github.com/ragnarstolsmark/migratortest
The migrate method takes a an array of migrations, filters them by those who have already been applied and executes them in sequence. The applied migrations is then stored in local storage under a key called: "appliedMigrations".
#### getAppliedMigrations
This returns an array of those appliedMigrations that have been stored in local storage. They are returned in the order they was applied. An appliedMigration consist of:
- name: The name of the migration that has been applied
- dateApplied: The date the migration was applied
#### storeAppliedMigrations
This takes an array of appliedMigration objects and stores them in local storage. This can work like a reset method when calling it with an empty array.