rxdb-dynamic-defaults

Dynamic Defaults Plugin for RxDB.

What it does

RxDB's schema default values are static. This plugin lets you assign defaults that are computed at insert time — per field or for the whole document.

Install

npm install @kampfcaspar/rxdb-dynamic-defaults

RxDB ^17.3 is required as peer dependency. As it fixes a bug with composite primary keys being checked before pre-insert hooks are called.

Usage

Import and register the plugin once:

import { addRxPlugin } from 'rxdb';
import { DynamicDefaultsPlugin } from '@kampfcaspar/rxdb-dynamic-defaults';

addRxPlugin(DynamicDefaultsPlugin);

Then configure dynamicDefaults in your collection options:

Static defaults per field

collection: {
  schema: mySchema,
  options: {
    dynamicDefaults: {
      name: 'default name',
      age: 10
    }
  }
}

Dynamic defaults per field

collection: {
  schema: mySchema,
  options: {
    dynamicDefaults: {
      createdAt: () => new Date().toISOString(),
      fullName: (doc) => `${doc.firstName} ${doc.lastName}`,
      slug: (doc, collection, key) => doc.title.toLowerCase().replace(/\s+/g, '-')
    }
  }
}

Document-level default callback

collection: {
  schema: mySchema,
  options: {
    dynamicDefaults: (doc, collection) => {
      doc.createdAt ??= new Date().toISOString();
      doc.id ??= crypto.randomUUID();
    }
  }
}

Behavior

• Defaults are only applied when a field is absent or undefined.
• Schema default values run first; dynamicDefaults are applied afterwards.
• Callbacks receive the document being inserted, the collection, and (for field-level) the property key.

License

AGPL-3.0-or-later