cassiusvm / mapstructcycle

Application about MapStruct mappings

MapStruct Cycle

In mapstruct-mapping-with-cycles the cycle stops at data access level but not at json level when you try to convert the dto to json because the dto's still have the dependencies on each other.

The main branch shows the use case.

The branch attempttosolve1 use the mapstruct-mapping-with-cycles strategy, it solves the cycle at data access level but not at json level. Try: http://localhost:8080/mother

The branch attempttosolve2 use the "Update 2" strategy from Prevent Cyclic references when converting with MapStruct, it solves the both the cycles at data access level and at json level.

Unfortunately, the "Update 2" strategy is some cumbersome when you have a more complex use case, for example: Father->Child->Pet.

I solved the cycle at json level on attempttosolve1 by using @AfterMapping ans setting the ofending dependencies to null.

mapstructcycle's Issues

Cycle still occurs at json level

Despite the solution by #2 the cycle still occurrs at json level.

s.e.ErrorMvcAutoConfiguration$StaticView : 
Cannot render error page for request [/mother] and exception 
[Could not write JSON: Infinite recursion (StackOverflowError); nested exception is 
com.fasterxml.jackson.databind.JsonMappingException: Infinite recursion (StackOverflowError) (through reference chain:
br.eti.cvm.mapstructcycle.dto.MotherDto["children"]->java.util.HashSet[0]->br.eti.cvm.mapstructcycle.dto.ChildDto["mother"]->
br.eti.cvm.mapstructcycle.dto.MotherDto["children"]->java.util.HashSet[0]->br.eti.cvm.mapstructcycle.dto.ChildDto["mother"]->

Application Failed to Start

org.springframework.beans.factory.BeanCurrentlyInCreationException: Error creating bean with name 'childMapperImpl': Requested bean is currently in creation: Is there an unresolvable circular reference?

***************************
APPLICATION FAILED TO START
***************************

Description:

The dependencies of some of the beans in the application context form a cycle:

   childController (field private br.eti.cvm.mapstructcycle.mapper.ChildMapper br.eti.cvm.mapstructcycle.controller.ChildController.childMapper)
┌─────┐
|  childMapperImpl (field private br.eti.cvm.mapstructcycle.mapper.MotherMapper br.eti.cvm.mapstructcycle.mapper.ChildMapperImpl.motherMapper)
↑     ↓
|  motherMapperImpl (field private br.eti.cvm.mapstructcycle.mapper.ChildMapper br.eti.cvm.mapstructcycle.mapper.MotherMapperImpl.childMapper)
└─────┘


Action:

Relying upon circular references is discouraged and they are prohibited by default. Update your application to remove the dependency cycle between beans. As a last resort, it may be possible to break the cycle automatically by setting spring.main.allow-circular-references to true.

Disconnected from the target VM, address: '127.0.0.1:52313', transport: 'socket'

Process finished with exit code 0

To add id and remove unnecessary object on main

To Solve cycle at json level on branch attempttosolve1

Using @AfterMapping is possible to set the offending dependency to null so avoiding the cycle.

Cycle at endpoint call

The application starts but when the endpoint /mother is called then the cycles occurs.

java.lang.StackOverflowError: null
	at java.base/java.util.HashMap.tableSizeFor(HashMap.java:378) ~[na:na]
	at java.base/java.util.HashMap.<init>(HashMap.java:451) ~[na:na]
	at java.base/java.util.HashMap.<init>(HashMap.java:462) ~[na:na]
	at java.base/java.util.HashSet.<init>(HashSet.java:146) ~[na:na]
	at br.eti.cvm.mapstructcycle.mapper.ChildMapperImpl.toDto(ChildMapperImpl.java:70) ~[classes/:na]
	at br.eti.cvm.mapstructcycle.mapper.MotherMapperImpl.toDto(MotherMapperImpl.java:45) ~[classes/:na]
	at br.eti.cvm.mapstructcycle.mapper.ChildMapperImpl.toDto(ChildMapperImpl.java:45) ~[classes/:na]

To add id and remove unnecessary object on attempttosolve1

To make attemptosolve1 branch json objects equals to ones on attempttosolve2 branch.