A pubsub notifier extension

Table of Contents

• pub_sub
  • publish
  • publish_all

pub_sub

A section for configuring how resource actions are published over pubsub

• publish
• publish_all

Examples:

pub_sub do
  module MyEndpoint
  prefix "post"

  publish :destroy, ["foo", :id]
  publish :update, ["bar", :name] event: "name_change"
  publish_all :create, "created"
end

• :module - Required. The module to call broadcast/3 on e.g module.broadcast(topic, event, message).

• :prefix - A prefix for all pubsub messages, e.g users. A message with created would be published as users:created

publish

Configure a given action to publish its results over a given topic.

If you have multiple actions with the same name (only possible if they have different types), use the type option, to specify which type you are referring to. Otherwise the message will be broadcast for all actions with that name.

To include attribute values of the resource in the message, pass a list of strings and attribute names. They will ultimately be joined with :. For example:

prefix "user"

publish :create, ["created", :user_id]

This might publish a message to "user:created:1"" for example.

For updates, if the field in the template is being changed, a message is sent to both values. So if you change user 1 to user 2, the same message would be published to user:updated:1 and user:updated:2. If there are multiple attributes in the template, and they are all being changed, a message is sent for every combination of substitutions.

Template parts

Templates may contain lists, in which case all combinations of values in the list will be used. Add nil to the list if you want to produce a pattern where that entry is ommitted.

The atom :_tenant may be used. If the changeset has a tenant set on it, that value will be used, otherwise that combination of values is ignored. For example:

The atom :_skip may be used. It only makes sense to use it in the context of a list of alternatives, and adds a pattern where that part is skipped.

publish :updated, [[:team_id, :_tenant], "updated", [:id, nil]]

Would produce the following messages, given a team_id of 1, a tenant of org_1, and an id of 50:

"1:updated:50"
"1:updated"
"org_1:updated:50"
"org_1:updated"

Introspection Target:

Ash.Notifier.PubSub.Publication

Examples:

publish :create, "created"

publish :assign, "assigned"

• :action - Required. The name of the action that should be published

• :topic - Required. The topic to publish

• :event - The name of the event to publish. Defaults to the action name

publish_all

Works just like publish, except that it takes a type and publishes all actions of that type

Introspection Target:

Ash.Notifier.PubSub.Publication

Examples:

publish_all :create, "created"

• :type - In the case of multiple actions with the same name, you may need to provide the action type as well.

• :action - The name of the action that should be published

• :topic - Required. The topic to publish

• :event - The name of the event to publish. Defaults to the action name