Why is my converted column marked by JpaAttributeTypeInspection with the error message "'Basic' attribute type should not be a map"?

Question

I was trying to store some JSON as a string in a column via JPA and Spring and was following a baeldung tutorial. My code like this:

    @Column
    @Convert(converter = MyEntityExtentionConverter.class)
    private Map<String, Object> myEntityExtention;

MyEntityExtentionConverter is an implementation of javax.persistence.AttributeConverter<Map<String, Object>, String> that converts the string back and forth using the Jackson ObjectMapper.

According to mentioned tutorial this should have been it, however now I get an Error that

'Basic' attribute type should not be a map

Theoretically I could disable it by adding @SuppressWarnings("JpaAttributeTypeInspection") to the annotations, but that feels like ignoring rather than solving the error. What am I doing wrong here?

Answer 1

Look like this is an issue from IntelliJ IDEA:

https://youtrack.jetbrains.com/issue/IDEA-270687

We can use workaround by this way: Using the @SuppressWarnings("JpaAttributeTypeInspection") annotation removes the warning.

Answer 2

You have to annotate prop "myEntityExtention" with @Type but is not possible to add both @Type and @Convert..

as you can see in this tutorial you have to define the json type on the top of your entity:

@Entity
@Table(name = "some_table_name")
@TypeDef(name = "json", typeClass = JsonStringType.class)
public class CustomEntity {

then add @Type annotation instead @Convert:

@Type( type = "json" )
private Map<String, Object> myEntityExtention;

be sure to add all the right dependencies/versions.

I.E. i'm using hibernate 5.4 so my dependencies are:

<!-- Hibernate ORM core version 5.4.21.Final (inherited from spring-boot 2.3.4)-->
<parent>
        <groupId>org.springframework.boot</groupId>
        <artifactId>spring-boot-starter-parent</artifactId>
        <version>2.3.4.RELEASE</version>        
 </parent>
<dependencies>
    <dependency>
        <groupId>com.fasterxml.jackson.datatype</groupId>
        <artifactId>jackson-datatype-hibernate5</artifactId>
        <version>2.8.4</version>
    </dependency>
    <dependency>
            <groupId>com.vladmihalcea</groupId>
            <artifactId>hibernate-types-52</artifactId>
            <!--for hibernate >= 5.2-->
            <version>2.10.2</version>
    </dependency>
</dependencies>

Answer 3

That field is not meant to be persisted. Remove the @Column annotation and use @Transient. You are supposed to persist it as a JSON which will be done in the customerAttributeJSON, when reading from the database the customerAttributes will be populated and you can use it with DTOs.

@Entity
@Table(name = "Customers")
public class Customer {
 
    @Id
    private int id;
 
    private String firstName;
 
    private String lastName;
 
    private String customerAttributeJSON;
 
    @Transient
    @Convert(converter = HashMapConverter.class)
    private Map<String, Object> customerAttributes;
}