Context:

Need to standardize business object mapping.

Decision:

Use three types of mappers: Client Side, Backend side for ServiceLayer <-> Domain, and Domain <-> PersistenceLayer.

Pros:

• Separation of concerns.
• Promotes long-term flexibility.

Cons:

• None

Status: Accepted -> In use

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Additional Content

UML

Client - ViewModel <-> ConnectorLayer

header Case 1
title Rule: Mapping between View Model (VM) and DTO in the VM Layer 

group addItem() action
	group prepare item to send to service
		cli.pre.vm -> cli.app.mapdto : toDto(vm)
		cli.app.mapdto -> cli.pre.vm : return dto
	end
	
	group action - request
		cli.pre.vm -> connectors.service : save(dto)
		connectors.service -> cli.pre.vm : dto getItem(int)
	end
	
	group prepare item to receive by view model layer
		cli.pre.vm -> cli.app.mapdto : toVm(dto)
		cli.app.mapdto -> cli.pre.vm : return vm
	end
end

Backend - ServiceLayer <-> Domain

header Case 2
title  Passing DTO to the Domain Layer

group addSomeItem(dto)
	group pass value - mapping to domain
		serviceLayer -> service.mapper : toDomain(dto)
		service.mapper -> serviceLayer : return domainObj
	end
	
	group action - pass to domain layer
		serviceLayer -> domainLayer : save(domainObj)
		domainLayer -> serviceLayer : domainObj getItem(int)
	end
	
	group return value - mapping to dto
		serviceLayer -> service.mapper : toDto(domainObj)
		service.mapper -> serviceLayer : return dto
	end
end

Backend - Domain <-> PersistenceLayer

header Case 3
title  Persisting Domain object

group save(entity)
	group pass value - mapping domain to entity
		domainLayer -> repo.mapper : toRepo(entity)
		repo.mapper -> domainLayer : return domainObj
	end
	
	group action - pass to repository layer
		domainLayer -> persistanceLayer : save(entity)
		persistanceLayer -> domainLayer : entity getItem(int)
	end
	
	group return value - mapping entity to domain
		domainLayer -> repo.mapper : toDomain(entity)
		repo.mapper -> domainLayer : return domainObj
	end
end