Examples

Pet management

Five workflows across owner, pet, and pet-type contexts.

state_changestate_view

The rendered canvas

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The source

Source file: examples/pet-management-detailed.em.hcl.

# Pet-management model using bounded-context-owned events and reusable field types. actor "clinic_staff" { title = "Clinic staff" auth_required = true } bounded_context "owner_management" { title = "Owner Management" aggregate "owner" { } field_type "owner_id" { type = "Int" id_attribute = true example = 42 } field_type "owner_name" { type = "String" pii = true example = "Darcy" } field_type "owner_email" { type = "String" optional = true pii = true example = "darcy@example.test" } event "owner_registered" { title = "Owner Registered" field "owner_id" { type = field_type.owner_id } field "owner_name" { type = field_type.owner_name } field "owner_email" { type = field_type.owner_email } } } bounded_context "pet_management" { title = "Pet Management" aggregate "pet" { } field_type "pet_id" { type = "Int" id_attribute = true example = 5 } field_type "pet_name" { type = "String" pii = true example = "Mochi" } field_type "birth_date" { type = "Date" optional = true example = "2020-01-12" } field_type "pet_type" { type = "String" example = "Cat" } field_type "owner_pets" { cardinality = "List" type = "Custom" example = [{ id = 5 name = "Mochi" birthDate = "2020-01-12" type = "Cat" }] subfield "id" { type = "Int" id_attribute = true } subfield "name" { type = "String" } subfield "birth_date" { type = "Date" } subfield "type" { type = "String" } } event "pet_added" { title = "Pet Added" aggregate = aggregate.pet aggregate_dependencies = [aggregate.owner_management.owner] field "pet_id" { type = field_type.pet_id } field "pet_name" { type = field_type.pet_name } field "birth_date" { type = field_type.birth_date } field "pet_type" { type = field_type.pet_type } field "owner_id" { type = field_type.owner_management.owner_id } } event "pet_details_updated" { title = "Pet Details Updated" aggregate = aggregate.pet field "pet_id" { type = field_type.pet_id } field "owner_id" { type = field_type.owner_management.owner_id } field "pet_name" { type = field_type.pet_name } field "birth_date" { type = field_type.birth_date } field "pet_type" { type = field_type.pet_type } } } bounded_context "pet_type_catalog" { title = "Pet Type Catalog" aggregate "pet_type" { } field_type "pet_type_id" { type = "Int" id_attribute = true example = 1 } field_type "pet_type_name" { type = "String" example = "Cat" } event "pet_type_added" { title = "Pet Type Added" aggregate = aggregate.pet_type field "pet_type_id" { type = field_type.pet_type_id } field "pet_type_name" { type = field_type.pet_type_name } } } state_view "list_pet_types" { title = "List Pet Types" description = "Display catalogued pet types before a clinician adds a pet." readmodel "pet_type_list" { title = "Pet Type List" question = "Which pet types can be selected?" from = [event.pet_type_catalog.pet_type_added] to = [screen.pet_type_picker] field "types" { cardinality = "List" type = "Custom" example = [{ id = 1 name = "Cat" }] subfield "id" { type = "Int" id_attribute = true } subfield "name" { type = "String" } } } screen "pet_type_picker" { title = "Pet Type Picker" actor = actor.clinic_staff } scenario "pet_types_available" { title = "Pet types are available" given { title = "Pet Type Added" event = event.pet_type_catalog.pet_type_added } then { title = "Pet Type List" readmodel = readmodel.pet_type_list } } } state_change "add_pet" { title = "Add Pet" description = "Register a new pet for an existing owner with validation." screen "add_pet_form" { title = "Add Pet Form" actor = actor.clinic_staff to = [command.add_pet_command] } command "add_pet_command" { title = "Add Pet" aggregate = aggregate.pet_management.pet aggregate_dependencies = [aggregate.owner_management.owner] api_endpoint = "POST /owners/{ownerId}/pets" creates_aggregate = true to = [event.pet_management.pet_added] field "owner_id" { type = field_type.owner_management.owner_id } field "pet_name" { type = field_type.pet_management.pet_name } field "birth_date" { type = field_type.pet_management.birth_date } field "pet_type" { type = field_type.pet_management.pet_type } } scenario "add_pet_success" { title = "Add pet successfully" given { title = "Owner exists" event = event.owner_management.owner_registered field "owner_id" { type = field_type.owner_management.owner_id } } when { title = "Add Pet" command = command.add_pet_command field "pet_name" { type = field_type.pet_management.pet_name } field "birth_date" { type = field_type.pet_management.birth_date } field "pet_type" { type = field_type.pet_management.pet_type } } then { title = "Pet Added" event = event.pet_management.pet_added field "pet_id" { type = field_type.pet_management.pet_id } field "pet_name" { type = field_type.pet_management.pet_name } } } scenario "add_pet_validation_error" { title = "Reject missing pet name" when { title = "Add Pet without a name" command = command.add_pet_command } then { title = "Validation Error" expect_empty_list = true error = "Pet name is required" } comment { description = "A pet must have a name before it can be registered." } } } state_view "load_pet_details" { title = "Load Pet Details" description = "Load the current pet details before a clinician edits the pet." readmodel "pet_details" { title = "Pet Details" question = "What are the current details of this pet?" from = [event.pet_management.pet_added] to = [screen.pet_details_screen] field "pet_id" { type = field_type.pet_management.pet_id } field "pet_name" { type = field_type.pet_management.pet_name } field "birth_date" { type = field_type.pet_management.birth_date } field "pet_type" { type = field_type.pet_management.pet_type } } screen "pet_details_screen" { title = "Pet Details Screen" actor = actor.clinic_staff } scenario "pet_details_loaded" { title = "Pet details are loaded" given { title = "Pet Added" event = event.pet_management.pet_added } then { title = "Pet Details" readmodel = readmodel.pet_details field "pet_id" { type = field_type.pet_management.pet_id } } } } state_change "edit_pet" { title = "Edit Pet" description = "Modify existing pet details with validation." screen "edit_pet_form" { title = "Edit Pet Form" actor = actor.clinic_staff to = [command.edit_pet_command] } command "edit_pet_command" { title = "Edit Pet" aggregate = aggregate.pet_management.pet to = [event.pet_management.pet_details_updated] field "pet_id" { type = field_type.pet_management.pet_id } field "pet_name" { type = field_type.pet_management.pet_name } field "birth_date" { type = field_type.pet_management.birth_date } field "pet_type" { type = field_type.pet_management.pet_type } } scenario "edit_pet_success" { title = "Edit pet successfully" given { title = "Pet exists" event = event.pet_management.pet_added field "pet_id" { type = field_type.pet_management.pet_id } } when { title = "Edit Pet" command = command.edit_pet_command field "pet_name" { type = field_type.pet_management.pet_name } } then { title = "Pet Details Updated" event = event.pet_management.pet_details_updated field "pet_id" { type = field_type.pet_management.pet_id } } } } state_view "show_owner_details" { title = "Show Owner Details" description = "Display owner information and the current registered pet list after owner and pet changes." readmodel "owner_details" { title = "Owner Details" question = "What are the owner's details and registered pets?" from = [ event.owner_management.owner_registered, event.pet_management.pet_added, event.pet_management.pet_details_updated, ] to = [screen.owner_details_screen] field "owner_id" { type = field_type.owner_management.owner_id } field "owner_name" { type = field_type.owner_management.owner_name } field "owner_email" { type = field_type.owner_management.owner_email } field "owner_pets" { type = field_type.pet_management.owner_pets } } screen "owner_details_screen" { title = "Owner Details Screen" actor = actor.clinic_staff } scenario "owner_details_updated" { title = "Owner details reflect a pet update" given { title = "Pet Details Updated" event = event.pet_management.pet_details_updated } then { title = "Owner Details" readmodel = readmodel.owner_details field "owner_id" { type = field_type.owner_management.owner_id } field "owner_pets" { type = field_type.pet_management.owner_pets } } } }