Metadata Cache

Under the hood, MikroORM uses ts-morph to read TypeScript source files of all entities to be able to detect all types. Thanks to this, defining the type is enough for runtime validation.

This process can be a bit slow, mainly because ts-morph will scan all your source files based on your tsconfig.json. You can speed up this process by whitelisting only the folders where your entities are via entitiesDirsTs option.

After the discovery process ends, all metadata will be cached. By default, FileCacheAdapter will be used to store the cache inside ./temp folder to JSON files.

Automatic Invalidation

Entity metadata are cached together with modified time of the source file, and every time the cache is requested, it first checks if the cache is not invalid. This way you can forgot about the caching mechanism most of the time.

One case where you can end up needing to wipe the cache manually is when you work withing a git branch where contents of entities folder differs.

Disabling Metadata Cache

You can disable caching via:

await MikroORM.init({
cache: { enabled: false },
// ...
});

Pretty Printing

By default, cached metadata will be one line JSON string. You can force pretty printing it:

await MikroORM.init({
cache: { pretty: true },
// ...
});

Using Different temp Folder

You can set the temp folder via:

await MikroORM.init({
cache: { options: { cacheDir: '...' } },
// ...
});

Providing Custom Cache Adapter

You can also implement your own cache adapter, for example to store the cache in redis. To do so, just implement simple CacheAdapter interface:

export interface CacheAdapter {
get(name: string): any;
set(name: string, data: any, origin: string): void;
}
export class RedisCacheAdapter implements CacheAdapter { ... }

And provide the implementation in cache.adapter option:

await MikroORM.init({
cache: { adapter: RedisCacheAdapter, options: { ... } },
// ...
});