vikunja-api/docs/content/doc/development/notifications.md

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---
date: 2021-02-07T19:26:34+02:00
title: "Notifications"
toc: true
draft: false
menu:
sidebar:
parent: "development"
---
# Notifications
Vikunjs provides a simple abstraction to send notifications per mail and in the database.
{{< table_of_contents >}}
## Definition
Each notification has to implement this interface:
```golang
type Notification interface {
ToMail() *Mail
ToDB() interface{}
Name() string
}
```
Both functions return the formatted messages for mail and database.
A notification will only be sent or recorded for those of the two methods which don't return `nil`.
For example, if your notification should not be recorded in the database but only sent out per mail, it is enough to let the `ToDB` function return `nil`.
### Mail notifications
A list of chainable functions is available to compose a mail:
```golang
mail := NewMail().
// The optional sender of the mail message.
From("test@example.com").
// The optional receipient of the mail message. Uses the mail address of the notifiable if omitted.
To("test@otherdomain.com").
// The subject of the mail to send.
Subject("Testmail").
// The greeting, or "intro" line of the mail.
Greeting("Hi there,").
// A line of text
Line("This is a line of text").
// An action can contain a title and a url. It gets rendered as a big button in the mail.
// Note that you can have only one action per mail.
// All lines added before an action will appearr in the mail before the button, all lines
// added afterwards will appear after it.
Action("The Action", "https://example.com").
// Another line of text.
Line("This should be an outro line").
```
If not provided, the `from` field of the mail contains the value configured in [`mailer.fromemail`](https://vikunja.io/docs/config-options/#fromemail).
### Database notifications
All data returned from the `ToDB()` method is serialized to json and saved into the database, along with the id of the
notifiable, the name of the notification and a time stamp.
If you don't use the database notification, the `Name()` function can return an empty string.
## Creating a new notification
The easiest way to generate a mail is by using the `mage dev:make-notification` command.
It takes the name of the notification and the package where the notification will be created.
## Notifiables
Notifiables can receive a notification.
A notifiable is defined with this interface:
```golang
type Notifiable interface {
// Should return the email address this notifiable has.
RouteForMail() string
// Should return the id of the notifiable entity
RouteForDB() int64
}
```
The `User` type from the `user` package implements this interface.
## Sending a notification
Sending a notification is done with the `Notify` method from the `notifications` package.
It takes a notifiable and a notification as input.
For example, the email confirm notification when a new user registers is sent like this:
```golang
n := &EmailConfirmNotification{
User: update.User,
IsNew: false,
}
err = notifications.Notify(update.User, n)
return
```
## Testing
The `mail` package provides a `Fake()` method which you should call in the `MainTest` functions of your package.
If it was called, no mails are being sent and you can instead assert they have been sent with the `AssertSent` method.
## Example
Take a look at the [pkg/user/notifications.go](https://code.vikunja.io/api/src/branch/master/pkg/user/notifications.go) file for a good example.