Dream Code for a Event Sourced DSL System

items.spec

context items

// Define commands and their respective events when they succeed.
// creatorId would be extracted from the context of the command
command CreateItem {
  title: String!
} -> ItemCreated {
  id: ID!
  title: String!
  creatorId: RefID!
  createdAt: Timestamp!
}

command DeleteItem {
  id: ID!
} -> ItemDeleted {
  id: ID!
  deletedAt: Timestamp!
}

command UpdateItem {
  id: ID!
  title: String
  note: String
} -> ItemUpdated {
  id: ID!
  title: String
  note: String
  updatedAt: Timestamp!  
}

// Define a view as its structure (array in this case) and what events feed into it
ItemCreated, ItemUpdated, ItemDeleted -> view Items [
  id: ID!
  title: String!
  note: String
  creatorId: RefID!
  categoryIds: [RefID]
  createdAt: Timestamp!
  updatedAt: Timestamp!
]

ItemCreated, ItemUpdated, ItemDeleted -> view Counts {
  deleted: Int!
  updated: Int!
  created: Int!
  currentCount: Int!
}

// members and admins can create items
allow CreateItem when $user.role = 'member' or $user.role = 'admin'

// allow members to update and delete only their own items
allow UpdateItem when $user.role = 'member' && Items[id].creatorId = $user.id
allow DeleteItem when $user.role = 'member' && Items[id].creatodId = $user.id


// allow admins to update and delete all items
allow UpdateItem when $user.role = 'admin'
allow DeleteItem when $user.role = 'admin'

// Allow everyone to read all items
allow Items

users.spec

context users

// Define commands and their respective events when they succeed.
command RegisterUser {
  email: Email!
  password: Password!
  passwordConfirm: Password!
} -> UserCreated {
  id: ID!
  email: Email!
  password: Password!
  createdAt: Timestamp!
}

command DeleteUser {
  id: ID!
} -> UserDeleted {
  id: ID!
  deletedAt: Timestamp!
}

command UpdateUser {
  id: ID!
  email: Email
  password: Password
  passwordCConfirm: Password
} -> UserUpdated {
  id: ID!
  email: Email
  password: Password
  updatedAt: Timestamp!  
}

// Define a view as its structure (array in this case) and what events feed into it
UserCreated, UserUpdated, UserDeleted -> view Users [
  id: ID!
  email: Email!
  // Note: password is not exposed here but can be used when filtering
  createdAt: Timestamp!
  updatedAt: Timestamp!
]

// guests and admins can create items
allow CreateUser when $user.role = 'guest' or $user.role = 'admin'

allow UpdateItem when $user.role = 'member' && Users[id].id = $user.id
allow DeleteItem when $user.role = 'member' && Users[id].id = $user.id

// allow admins to update and delete all items
allow UpdateItem when $user.role = 'admin'
allow DeleteItem when $user.role = 'admin'
  
  
// Allow members to read their own User
allow Users when id=$user.id && $user.role = 'member'

// Allow admins to read all users
allow Users when $user.role = 'admin'

// Guests can query for Users if they specify email and password in the filter. 
// The view handlers will perform the filtering internally and return matches
allow Users when $user.role = 'guest' && $filter.email && $filter.password