A Preference determines whether a given recipient (a user or an object) will receive a notification for a given workflow, channel, or workflow-channel pair.

In this guide we'll walk through how to set notification preferences for your recipients in Knock.

We'll start with a quick overview of the preferences model and how it ties into the rest of Knock, then we'll walk through how to set notification preferences for workflows, categories, and channels, as well as combinations of all three.

An overview of preferences

There are three different types of preferences we can set for our recipients in Knock: channel type preferences, workflow preferences, and workflow category preferences.

To see how they work let's start with a review of how Knock sends notifications to your recipients. You configure a workflow in Knock. When this workflow is called via a workflow trigger, it runs for every recipient sent in the triggering API call, sending them a notification on each channel configured in the workflow.

Preferences are per-recipient rules that tell Knock whether a notification should be delivered to a recipient based on its channel type, its workflow, and the workflow category that workflow belongs to (if any).

When the channel step executes in your workflow run, the recipient will only receive a notification if their preferences for the channel type, the workflow, and the workflow category all evaluate to true. To put this in inverse terms, if ANY preference related to a given channel step in a workflow evaluates to false, we will not send the recipient a notification. This makes sense, as receiving a notification you thought you opted out of is not a fun experience for recipients. 😁 (Note: if you do not set a preference for a given channel, workflow, or category, Knock defaults them to true.)

In the next section, we'll walk through this evaluation model in more detail and outline how to set preferences via the Knock preferences API.

The Knock preferences API

As mentioned in the previous section, there are three types of preferences you can set for your recipients: channel type, workflow, and workflow category. You can also use these preference types in combination with one another. We cover that below, too.

Channel type preferences

A channel type preference lets recipients opt out of notifications for an entire channel type. You can set preferences for all unique channel types configured within your account. (As an example, if I have three channels configured of type email, two channels configured of type push , and one channel configured of type in_app_feed , we can set channel preferences for email, push, and in_app_feed.)

Here's a JSON example of a given recipients's channel preferences.

In this example, the recipient wouldn't receive any notifications sent over email, as any email channel steps, regardless of their workflow or workflow category, would always evaluate to false. This makes channel preferences a good way to give your recipients a way to opt-out of ALL notifications sent across a given channel type, such as email or push. Once a recipient is opted into a channel type, you're relying on workflow and workflow category preferences to determine whether a given notification should be sent.

Workflow preferences

A workflow preference can be set for a specific workflow (e.g. a mention). When a recipient's preference for a given workflow is set to false, the recipient will not receive any notifications generated by that workflow across any channel type.

Here's a JSON example of a given recipient's workflow preferences.

In this example, the recipient would not receive any notifications from the new-reply workflow but would receive notifications from the new-comment workflow.

Workflow preferences are a great way to give your recipients a way to opt out of a given notification or type of notification across ALL channels.

Workflow category preferences

There are cases when you'll want to enable your recipients to set a preference for a category of workflows, for example, all of your workflows related to direct notifications. In these cases, rather than having to surface a preference control for each of those notification types, you can use categories to set the preference for multiple workflows at once.

To set a category for a given workflow, go to that workflow's page in the dashboard, click the "..." menu, and select "Manage workflow". From there you'll be able to add categories. (Note: A workflow can belong to multiple categories. In the instance that it does, and conflicting preferences are set across those categories, the workflow's preference will default to false.)

Here's an example of a given recipient's preferences for a set of workflow categories.

A note on category conflicts. If a workflow belongs to multiple categories, only one of those category preferences needs to evaluate to true for the notification to send.

Combining preferences

In many cases, you'll want to let recipients pick and choose which channels they want to be notified on about which workflows or workflow categories. This way they can opt into more disruptive channels (such as email and push) for notifications they deem important, and they can opt out of those channels on notifications they deem less important.

This is where you can combine preferences. When you want to enable a recipient to choose which channels they want to be notified on for a given workflow or category, you can specify a channel_types object within both the workflows and categories preferences.

Take an example of an app that wants to give per-channel preferences to its recipients on both its new-mention workflow and on its collaboration category. In the example below, the recipient has decided they want to receive mention notifications on all channels, but collaboration notifications on just the in-app channel.

Remember: in cases where a preference is set both for a workflow and for its parent category, Knock will only send a notification if all preference combinations that exist on the recipient evaluate to true. This means that in the case above, if the new-mention workflow belongs to the collaboration category, the recipient will not receive email notifications about new mentions, even though the preference is currently set to true.

Preference conditions

When working with preferences, you’ll sometimes run into advanced use cases where you need to provide even more granular preference options for your customers. For example: you may want to let a recipient mute notifications about a given resource in your product. That’s where preference conditions come into use in the Knock model: they provide a powerful way for you to add extra logic that’s computed during preference evaluation per recipient.

What is a condition?

A condition is one or more pieces of logic that are evaluated when computing the current state of a preference. Typically, preferences evaluate to boolean values representing if the recipient has opted in or out of receiving notifications on a given channel, workflow, or category. With preference conditions, you can add additional custom expressions to that set, where the notification is only sent if all preferences (including the preference condition statement) evaluate to true.

Note: multiple conditions are evaluated as ANDs.

Conditions can:

  • Reference data passed in your workflow trigger (the data payload)
  • Reference data stored on the recipient and actor
  • Evaluate against fixed values like booleans, strings, and integers
  • Evaluate against various types of operators, like ==, β‰ , IN, NOT IN and more

What can a condition be applied to?

A condition can be applied at different points in the preference set:

  • Inside workflows, categories, or channel_types preferences
  • Inside an individual workflows[workflow].channel_types preference
  • Inside an individual categories[category].channel_types preference

Available arguments and variables

You can use any of the following in arguments or variables:

  • recipient.* - target a property in the recipient
  • actor.* - target a property in the actor
  • data.* - target a property in the data payload
  • refs.* - target the result of a previous step
  • true / false / null
  • string / float

Available operators

You can use any of the following operators in condition comparisons:

containsargument in variable
not_containsargument not in variable
emptyvariable in ["", null, []]
not_emptyvariable not in ["", null, []]