https://answers.axonivy.com/questions/1745/avoid-multiplebagfetchexception-when-referencing-multiple-collections-of-another-type<p>I know how to store a single list in a JPA class. but now everytime i try to add another list to any other entity class i get an ivy:error:persistence, with following error message:</p> <pre><code>IvyScriptRuntimeException: IvyScript Runtime Exception in Instruction: ivy.persistence.axsosUnit.findAll(teamprojekt.Job.class) Block: teamprojekt.showDashboard.showDashboardData out; out = in; in.data.closedJobs = ivy.persistence.axsosUnit.findAll(teamprojekt.Job.class); IvyScriptMethodInvocationException: Error calling method findAll(java.lang.Class) on an object of class ch.ivyteam.ivy.process.data.persistence.internal.IvyEntityManager. PersistenceUnitException: Failed to excecute operation "findAll" for persistence unit "axsosUnit". PersistenceUnitException: Could not create EntityManagerFactory of persistence unit'axsosUnit' PersistenceException: [PersistenceUnit: axsosUnit] Unable to build EntityManagerFactory MultipleBagFetchException: cannot simultaneously fetch multiple bags </code></pre> <p>I have read, that you cant use two lists in the same entity class, but i use them in different entity classes. maybe because they are nested?</p> <p>the structure is: institutionList is inside education which is inside application which has the other list.</p> <p>I have also read, the solution is to use a set instead of a list. can you explain how to do this? I've tried to change the list to a set from the entity class wizzard, but without success.</p> <p>can you show me how to do this?</p> <p>thank you very much</p>enMon, 25 Apr 2016 09:35:02 -0400https://answers.axonivy.com/questions/1745/avoid-multiplebagfetchexception-when-referencing-multiple-collections-of-another-type/1747<p>Just go into the dataclass editor and write the new set type into the column 'Type'. </p> <p>In my <a href="/upfiles/simpleJpa_51.iar">example project</a> it would be be <code>java.util.Set&lt;simpleJpa.Phone&gt;</code></p> <p><img alt="alt text" src="https://answers.axonivy.com/upfiles/jpaSetField.png"></p>Reguel WermelingerMon, 25 Apr 2016 09:35:02 -0400https://answers.axonivy.com/questions/1745/avoid-multiplebagfetchexception-when-referencing-multiple-collections-of-another-type/1747