Remult

# Remult > Remult is a TypeScript library for building full-stack apps without boilerplate. Define entities once and use them on the frontend, the backend, and in the database, with a single SSOT (Single Source of Truth) for schema, validation, permissions, and CRUD. ## Core Concepts - **Entity** - a TypeScript class decorated with `@Entity('key', options)` is your SSOT: schema, REST API, validation, permissions, and lifecycle in one place. - **Fields** - `@Fields.string()`, `.number()`, `.boolean()`, `.date()`, `.json()`, `.uuid()`, `.cuid()`, `.autoIncrement()`, plus `@Relations.toOne()` / `.toMany()` for entity links. - **Repository (`repo(Entity)`)** - universal CRUD: `.find()`, `.findFirst()`, `.findId()`, `.insert()`, `.update()`, `.delete()`, `.save()`, `.count()`, `.query()`, `.liveQuery()`. Same API on frontend and backend. - **Permissions** - entity-level `allowApiRead/Insert/Update/Delete/Crud` and per-field `allowApiUpdate`; values are boolean, role string, role array, or `(entity, remult) => boolean`. Use `apiPrefilter` / `backendPrefilter` for row-level filtering. - **Lifecycle hooks** - `validation`, `saving`, `saved`, `deleting`, `deleted` run on the server before/after persistence; `saving` mutates the entity in place. - **BackendMethod** - `@BackendMethod({ allowed })` exposes a server-only function callable from the client; runs in the server context with `remult.user` populated. - **Live queries** - `repo(X).liveQuery(options).subscribe(({ items, changes }) => ...)` pushes inserts/updates/deletes to all connected clients over SSE. - **Custom filters** - `Filter.createCustom` / `SqlDatabase.filterToRaw` to express complex queries that round-trip to the server safely. - **Validators** - built-ins under `Validators.*` (`required`, `min`, `max`, `email`, `url`, `unique`, `regex`, `enum`, ...) or `validate: (entity) => string | undefined` for custom logic. - **Admin UI** - turnkey `/api/admin` panel via `admin: true` (or `admin: { allow: 'admin' }`) in `remultApi()`. - **Stacks** - frameworks: React, Angular, Vue, SvelteKit, Next.js, SolidStart, Nuxt. Servers: Express, Fastify, Hono, Elysia, Hapi, Koa, NestJS. Databases: PostgreSQL, MySQL, MongoDB, SQLite (better/sqljs/bun), MSSQL, Turso, DuckDB, Oracle, Cloudflare D1, JSON files. ## Documentation ### Getting Started - [Introduction](https://remult.dev/docs/): Introduction - fullstack CRUD framework deriving REST API, type-safe client, and query builder from TS model classes. - [Creating a project](https://remult.dev/docs/creating-a-project): Scaffold a new project with npm init remult@latest - 180+ framework/server/DB/auth combinations. - [Quickstart](https://remult.dev/docs/quickstart): Install remult and wire remultApi middleware into Express, Fastify, Next.js, SvelteKit, and friends. - [Example Apps](https://remult.dev/docs/example-apps): Gallery of example apps - TodoMVC, CRM, shadcn/TanStack tables, ready-to-play sandboxes. ### Entities - [Entities](https://remult.dev/docs/entities): The SSOT class - schema, REST API, validation, and permissions in one @Entity decorator. - [Fields](https://remult.dev/docs/field-types): Built-in @Fields decorators - string, number, integer, boolean, date, dateOnly, json, object, literal. - [Relations](https://remult.dev/docs/entity-relations): @Relations.toOne / @Relations.toMany - define and navigate one-to-one, one-to-many, many-to-many associations. - [Filtering and Relations](https://remult.dev/docs/filtering-and-relations): Querying across one-to-many relations - inline where, nested filters, and reusable custom filters. - [Lifecycle Hooks](https://remult.dev/docs/lifecycle-hooks): Entity hooks - validation, saving, saved, deleting, deleted - for custom logic at persistence boundaries. - [Migrations](https://remult.dev/docs/migrations): Automatic ensureSchema sync vs. explicit migration files generated and applied via the migrations CLI. - [Generate from Existing DB](https://remult.dev/docs/entities-codegen-from- […gekürzt]