# sequelize-sync-diff

> Uses Sequelize.sync() but generates ALTER statements instead of DROP+CREATE

Latest version **0.2.3** (published 2016-05-28) · MIT license · 0 weekly downloads

## Install

```sh
npm install sequelize-sync-diff
pnpm add sequelize-sync-diff
yarn add sequelize-sync-diff
bun add sequelize-sync-diff
```

## Health

**Score 15/100 (F)** — status: abandoned.

Positive: no vulnerabilities.

Warnings: low downloads; no types; no esm support; pre 1.0.

Negative: abandoned; low maintenance score.

## Facts

| | |
|---|---|
| Version | 0.2.3 |
| Published | 2016-05-28 |
| First published | 2016-01-06 |
| Weekly downloads | 0 |
| License | MIT |
| TypeScript types | none |
| Module format | CommonJS |
| Dependencies | 1 |
| Known vulnerabilities | 0 |
| Install scripts | no |
| Author | Alberto Gimeno |
| Maintainers | gimenete |
| Keywords | sequelize, sync, alter |

## Links

- npm: https://www.npmjs.com/package/sequelize-sync-diff
- Repository: https://github.com/gimenete/sequelize-sync-diff
- Homepage: https://github.com/gimenete/sequelize-sync-diff#readme
- Issues: https://github.com/gimenete/sequelize-sync-diff/issues
- npm.io page: https://npm.io/package/sequelize-sync-diff

## Dependencies (1)

- [dbdiff](https://npm.io/package/dbdiff.md) ^0.4.2

## Recent versions

- 0.2.3 (latest) — 2016-05-28
- 0.2.2 — 2016-05-28
- 0.2.1 — 2016-05-23
- 0.2.0 — 2016-05-17
- 0.1.1 — 2016-02-03
- 0.1.0 — 2016-01-06

## README

# sequelize-sync-diff

Uses `Sequelize.sync()` but generates ALTER statements instead of DROP+CREATE.

**Only works for postgres right now**. Please open an issue if you need support for other databases.

## How it works

`sequelize-sync-diff` syncs your schema with your database using `sequelize.sync({ force: false })` and you need to provide a _dummy_ database where it will recreate the same schema you have and will call `.sync()` but this time with `{ force: true }`. So at this point you have your working database not fully up to date since `sync()` has its limitations but you have a _dummy_ empty database but with the full schema your data models need. Then, internally, [https://github.com/gimenete/dbdiff](dbdiff) is used to compare both databases and you get the SQL required to execute in your working database to be up to date with your data model changes.

## Installing

```
npm install sequelize-sync-diff
```

## Usage

```javascript
// Before defining anything in your data model you need this code:
var Sequelize = require('sequelize')
require('sequelize-sync-diff')(Sequelize)
// At this point Sequelize has the new syncDiff() method injected
// and some code has been injected for introspecting the data model


// Use Sequelize as you always do
var sequelize = new Sequelize('postgres://user:pass@localhost/database', {})

var User = sequelize.define('User', {/* ... */})
var Project = sequelize.define('Project', {/* ... */})
Project.hasOne(User)

// Now is time to use .syncDiff()
sequelize.sync()
  .then(() => sequelize.syncDiff('postgres://aro:aro@localhost/database_dummy'))
  .then(function(sql) {
    // Here we have the ALTER statemetns
    console.log(sql)
  })
```

## Caveats

The SQL statements are returned to you and they are not executed for a good reason: there are scenarios on which this will cause data loss (e.g. dropping a column). Also some statements could fail depending on the data you have in your working database (e.g. changing the data type of a column or setting it to NOT NULL). For more information please check [dbdiff caveats](https://github.com/gimenete/dbdiff#caveats).

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