The data contract

Your contract is the file where you declare models, their fields and how they relate. Everything else — migrations, the client, its types — is generated from it.

A first contract

contract.strata.ts

import { model, id, text, email, timestamp, relation } from "@strata/contract";export const User = model("User", {  id: id(),  email: email().unique(),  name: text().optional(),  posts: relation.many(() => Post),});export const Post = model("Post", {  id: id(),  title: text(),  published: boolean().default(false),  author: relation.one(() => User),  createdAt: timestamp().defaultNow(),});

Field types

Builder	PostgreSQL	SQLite	TypeScript
`id()`	`uuid`	`text`	`string`
`text()`	`text`	`text`	`string`
`int()`	`integer`	`integer`	`number`
`boolean()`	`boolean`	`integer`	`boolean`
`timestamp()`	`timestamptz`	`text`	`Date`
`json()`	`jsonb`	`text`	`unknown`

Modifiers

.optional() makes the column nullable and the field T | null
.unique() adds a unique index
.default(value) and .defaultNow() set a database default
.map("column_name") keeps a legacy column name

Renaming a field without .map() drops the column and creates a new one. strata migrate dev warns you before it does; strata migrate deploy does not ask.

Updated Oct 12, 2026

Was this page helpful?

The data contract

Your contract is the file where you declare models, their fields and how they relate. Everything else — migrations, the client, its types — is generated from it.

A first contract

contract.strata.ts

import { model, id, text, email, timestamp, relation } from "@strata/contract";export const User = model("User", {  id: id(),  email: email().unique(),  name: text().optional(),  posts: relation.many(() => Post),});export const Post = model("Post", {  id: id(),  title: text(),  published: boolean().default(false),  author: relation.one(() => User),  createdAt: timestamp().defaultNow(),});

Field types

Builder	PostgreSQL	SQLite	TypeScript
`id()`	`uuid`	`text`	`string`
`text()`	`text`	`text`	`string`
`int()`	`integer`	`integer`	`number`
`boolean()`	`boolean`	`integer`	`boolean`
`timestamp()`	`timestamptz`	`text`	`Date`
`json()`	`jsonb`	`text`	`unknown`

Modifiers

.optional() makes the column nullable and the field T | null
.unique() adds a unique index
.default(value) and .defaultNow() set a database default
.map("column_name") keeps a legacy column name

Renaming a field without .map() drops the column and creates a new one. strata migrate dev warns you before it does; strata migrate deploy does not ask.

Updated Oct 12, 2026

Was this page helpful?