# Multi-tenancy

If you need to handle multi-tenancy in your new application, you can just reply with `yes` when you are being prompted about this topic at the beginning and voilà! Everything will be done for you.

This feature comes with a middleware function that identifies the tenant on every request using different strategies. 

By default it first looks for the *tenantId* in the query string ( `request.query.tenantId` ), if not there then we'll decode the token and try to extract it from there. 

You can use other strategies of tenant identification, we also included some you can choose from or you can define your own.

```javascript
const tenantIdentification = () => async (ctx, next) => {
    if (!ctx.tenant) {
        const tenantId = R.ifElse(
            getTenantIdFromQueryString,
            getTenantIdFromJwt
        )(ctx)

        ctx.tenant = await tenantFactory.getTenantFromId(tenantId);
    }
    await next();
}

const getTenantIdFromJwt = ({ token }) => {
    let tenantId = null;
    if (token) {
        const decoded = jsonwebtoken.decode(token.replace("Bearer ", ""));
        if (decoded) {
            tenantId = decoded.tid;
        }
    }
    return tenantId;
}
const getTenantIdFromQueryString = ({ request }) => request.query.tenantId

const getTenantIdFromHeaders = ctx => ctx.req.headers.tenantid

const getTenantIdFromHost = ctx => ctx.hostname

const getTenantIdFromRefererHost = async ctx => {
    if (!ctx.request.headers.referer) {
        return;
    }
    var url = new URL.parse(ctx.request.headers.referer);
    return url.hostname
};
```

In addition, when choosing this option, you will find a `src/features/tenant` folder. This contains the infrastructure (query, resolvers, dataLoaders and api functions) you can use to manage multi-tenancy in your front-end application. 

{% hint style="info" %}
This is the missing piece for the **Tenant Selector** component, a part of the [Webapp Rocket Generator -> Multi-tenancy](https://github.com/osstotalsoft/generator-webapp-rocket#multi-tenancy).
{% endhint %}

When generating a multi-tenant application you are prompted with the following database questions:

* Use shared database (yes/no). In case multiple tenants share the same database, the tables will be filtered by a 'tenant id' column
* Database connection name. The connection information (server, database, user, password, etc.) will found in the tenant configuration under this name