Spring Boot Entity model member converter - spring

Question

Here my problem, I have to store serialized website's cookie information in DB, and I tried to write a simple PesistentConverter to it can be convert Map to String and vice-versa. But the IDE show a warning about this:
'Basic' attribute type should not be a map
Here my Entity:
#Entity
#Table(name = "website")
public class Website implements Serializable {
#Id
#Column(name = "name", length = 16, nullable = false)
#NotNull
private String name;
#Column(name = "serialized_cookie_map", nullable = false, length = 2048)
#Convert(converter = CookieMapPersistenceConverter.class)
#NotNull
private Map<String,String> serializedCookieMap;
...
}
CookieMapPersistenceConverter:
public class CookieMapPersistenceConverter implements AttributeConverter<Map<String, String>, String> {
#Override
public String convertToDatabaseColumn(Map<String, String> stringStringMap) {
return stringStringMap.toString();
}
#Override
public Map<String, String> convertToEntityAttribute(String s) {
ObjectMapper mapper = new ObjectMapper();
TypeFactory typeFactory = mapper.getTypeFactory();
MapType mapType = typeFactory.constructMapType(HashMap.class, String.class, String.class);
HashMap<String,String> convertedMap = null;
try {
convertedMap = mapper.readValue(s, mapType);
} catch (JsonProcessingException e) {
e.printStackTrace();
}
return convertedMap;
}
}
I'm using the 2.6.3 version of Spring Boot.
Many thanks your time!

Answer 1

According to this:
Any attributes that have no other annotations and do not reference
other entities will be automatically mapped as basic.
and according to the table from the above link map is not a basic type. so IDE is right about
'Basic' attribute type should not be a map
I suggest try the following approach to see it satisfies your requirements or not.
#Id
#Column(name = "id", length = 16, nullable = false)
#NotNull
private String id;
#ElementCollection
#MapKeyColumn(name="property")
#Column(name="value")
#CollectionTable(name="cookies", joinColumns=#JoinColumn(name="id"))
#NotNull
private Map<String,String> serializedCookieMap;
//setter and getter
and the code for repositry:
#Repository
public interface WebsiteRepository extends CrudRepository<Website, String> {}
code I did for test:
Website w = new Website();
w.setId("id");
Map<String, String> m = new HashMap<>();
m.put("key1", "value1");
m.put("key2", "value2");
m.put("key3", "value3");
w.setSerializedCookieMap(m);
repo.save(w);
which creates two table named WEBSITE and COOKIES and the content of each is like this:
WEBSITES:
ID
id
and:
COOKIES:
ID VALUE PROPERTY
id value1 key1
id value2 key2
id value3 key3
if you insist to store Serialized version of map take a look at this

Answer 2

I have tried same thing in my project (with same version of spring boot). I did not notice any warning.
But here are some suggestions...
The field you have annotated #convert not meant to be persisted in DB. So instead of #column try using #Transient.
You can also try using #Type( type = "json" ) instead of #convert.
Also this can be possibly issue with IDE, so just to ignore it as a
warning you can use #SuppressWarnings("JpaAttributeTypeInspection") annotation.