Why lazy init entity is null when assigned to DTO inside transaction boundary? - spring

Question

I am porting my legacy code to spring boot + angular application, which was spring + angular js earlier. My pojo has #ManyToOne relationship in it which is lazy.
When i try to create a DTO object from original object, the child object inside orginal object is null, when sent to client. In my legacy application same code works perfectly.
If i make it eager or i call sysout on that child element before creating DTO then it works, probably because getters of child object is called internally.
Parent object
public class ComponentInfo implements Serializable{
private static final long serialVersionUID = -1135710750835719391L;
#Id
#Column(name="TAGGING_KEY")
private String taggingKey;
#ManyToOne(fetch = FetchType.LAZY)
#JoinColumn(name = "COMPONENT_CONFIG_ID",nullable = true)
private ReportComponentConfig componentConfig;
#Column(name = "DESCRIPTION", length = 200)
private String description;
#Column(name = "ORIGINAL_FILE_NAME",length=50)
private String originalFileName;
#Column(name = "OVERRIDE_DOCUMENT")
private Boolean overrideDocument = false;
#Column(name = "START_DATE")
private Date startDate;
#OneToMany(mappedBy="componentInfo",cascade=CascadeType.ALL,orphanRemoval=true)
private List<TransactionComponentInfo> transactionComponentInfo = new ArrayList<>(0);
#Column(name = "SHOW_GLOBAL")
private Boolean showGlobal = false;
}
Child Object
public class ReportComponentConfig {
#Id
#TableGenerator(name = "COMPONENT_CONFIG_ID", table = "ID_GENERATOR", pkColumnName = "GEN_KEY", valueColumnName = "GEN_VALUE", pkColumnValue = "COMPONENT_CONFIG_ID", allocationSize = 1, initialValue = 1)
#GeneratedValue(strategy = GenerationType.TABLE, generator = "COMPONENT_CONFIG_ID")
#Column(name = "COMPONENT_CONFIG_ID", unique = true, nullable = false)
private int id;
#Column(name = "NAME", nullable = false, length = 200)
private String name;
#Column(name = "TAG", nullable = false, length = 200)
private String tag;
#Column(name = "COMP_CONFIG", nullable = false, columnDefinition = "VARCHAR(MAX)")
private String config;
#Column(name = "PUBLISHED_CONFIG", columnDefinition = "VARCHAR(MAX)")
private String publishedConfig;
#Column(name = "IS_PUBLISHED")
private boolean published = false;
#ManyToOne
#JoinColumn(name = "COMPONENT_ID", nullable = false)
private Component component;
#ElementCollection(fetch = FetchType.EAGER)
#CollectionTable(name = "CONFIG_REPORT_MAPPING", joinColumns = #JoinColumn(name = "COMPONENT_CONFIG_ID"))
#Column(name = "REPORT_ID")
private Set<Long> reports = new HashSet<>(0);
#ElementCollection(fetch = FetchType.LAZY)
#CollectionTable(name = "CONFIG_TRANSACTION_MAPPING", joinColumns = #JoinColumn(name = "COMPONENT_CONFIG_ID"))
#Column(name = "TRANSACTION_ID")
private Set<Long> transactions = new HashSet<>(0);
#Column(name = "VIEWS", columnDefinition = "VARCHAR(MAX)")
private String views;
}
DTO
public class ComponentInfoDTO implements Cloneable {
private ReportComponentConfig componentConfig;
private String taggingKey;
private String description;
private String originalFileName;
private Date startDate;
private Boolean overrideDocument;
private Boolean showGlobal;
private ComponentInfoDTO parentComponentInfo;
public ComponentInfoDTO() {
}
public ComponentInfoDTO(ComponentInfo ci, TransactionComponentInfo transactionComponentInfo) {
this.componentConfig = ci.getComponentConfig();//this is object is null
this.taggingKey = ci.getTaggingKey();
this.description = ci.getDescription();
this.originalFileName = ci.getOriginalFileName();
this.startDate = ci.getStartDate();
this.overrideDocument = ci.getOverrideDocument();
this.showGlobal = ci.getShowGlobal();
if (transactionComponentInfo != null) {
this.parentComponentInfo = this.clone();
this.startDate = transactionComponentInfo.getStartDate();
this.overrideDocument = transactionComponentInfo.getOverrideDocument();
this.description = transactionComponentInfo.getDescription();
this.originalFileName = transactionComponentInfo.getOriginalFileName();
this.showGlobal = true;
}
}
}
New Code image
Old Code image
Edit:
Both are same but in older case i get the child object on client side and in new case i get null.
This is the data i'm getting in my older application with lazy init
[ {
"componentConfig" : {
"id" : 3,
"name" : "Monthly Origination By Region",
"tag" : "CHART_monthlyOriginationByRegion",
"config" : "xyz",
"published" : true,
"component" : {
"id" : "CHART",
"name" : "Chart",
"defaultConfig" : null,
"htmlTag" : "<chart></chart>",
"filePath" : "chart/chart.component.js",
"dependentScriptsSrc" : [ ],
"dependencies" : null
},
"reports" : [ 3 ],
"transactions" : [ 2 ],
"views" : "{\"monthlyOriginationByRegion\": {\"key\": \"MONTHLY_ORIGINATION_BY_REGION\"}}"
},
"taggingKey" : "3",
"description" : "asdfasd\nasdfadf",
"originalFileName" : "Citi Tape - 2141 - GEBL0501 - 2019 Oct 04.xlsm",
"startDate" : "2019-10-28T18:30:00.000+0000",
"overrideDocument" : true,
"showGlobal" : true,
"parentComponentInfo" : null
} ]
This is the data in new application
[ {
"componentConfig" : null,
"taggingKey" : "3",
"description" : "asdfasd\nasdfadf",
"originalFileName" : "Citi Tape - 2141 - GEBL0501 - 2019 Oct 04.xlsm",
"startDate" : "2019-10-28T18:30:00.000+0000",
"overrideDocument" : true,
"showGlobal" : true,
"parentComponentInfo" : null
} ]
Component config should not be null, if make it eager fetch it works in new app but in my older application, it is working with lazy fetch.

Answer 1

What you see in the debugger window is a HibernateProxy. The fields of that proxy are never initialized! The getters are intercepted and delegated to the loaded entity which is located somewhere inside the proxy.
This means you have to never call fields directly, as you don’t know if the object is a proxy or your loaded entity. You always need to work on the getters.
How are you mapping the entity to the DTO? Most likely you use field access, while you should use the getters.