Simple task model

Simple task model: A step by step creation

First the namespace:

create namespace tasks

TaskStatus

Status values are defined as an enum, one create the enum in the tasks namespace.

create enum task_status [ready, in_progress, finished] > tasks

Let's add some values to the enum

task_status.enum << [draft, in_analysis, cancelled]

TaskEvent

Create the TaskEvent entity in the tasks namespace scope.

create entity task_event > tasks

Let's define some basic attributes on the entity task_event scope only and not in the namespace or global scope. Mandatory field !, zero or one: ?.

create attribute event_date! date > task_event
create attribute comment? string > task_event
create attribute new_status? task_status > task_event

Attribute event_type is a nested enum within task_event:

create attribute event_type! [status_changed, comment_added] > task_event

Add a new event type, i.e. a new value to the event_type enum.

task_event.event_type.enum << [task_created]

Task

create entity task > tasks

Create an alias with multiple ($*) placeholder to help in attribute creation, think of it as macro.

alias ca = create attribute $* > task

ca title! string
ca description? string
ca status! task_status
ca tags+ string
ca history* task_event

Mandatory field !, zero or one: ?, one or more: +, zero or more: *

Update the denormalized status whenever the history is modified:

task.history.onchange = function (event) { 
  var entity = event.entity; 
  var last_event = entity.history.last;
  // not all event have the new_status attribute filled
  if(last_event.event_type == 'status_changed)
    entity.status = last_event.new_status
}

Note the ' to indicate the following is a symbol: 'status_changed denotes a value of the enum