No converter found capable of converting from type [java.time.LocalDate] to type [@org.springframewo-CodePudding

I have a springboot project with mysql and jpa and in there I have a model/domain class

class MyClass {
    private long id;
    private String name;
    private LocalDate date;
    private String data1;
    private Integer data2;
}

and I also have repository interface that extends JpaRepository where I want to add a custom query to pick rows with latest date by name - the code is as follows:

interface MyClassRepository extends JpaRepository<MyClass, Long> {
    @Query(value = "select m.name, max(date) from MyClass m group by m.name")
    List<String> selectLatest();
}

When the call of that query is executed I get the error message as in the title

No converter found capable of converting from type [java.time.LocalDate] to type [@org.springframework.data.jpa.repository.Query java.lang.String]

I have found similar questions but each was more specific to a class and more complex than mine, I think it's the java.util.LocalDate that's the problem here?

CodePudding user response：

You select two columns which is not a string. Your message returns an Object[]:

interface MyClassRepository extends JpaRepository<MyClass, Long> {
    @Query(value = "select m.name, max(date) from MyClass m group by m.name")
    List<Object[]> selectLatest();
}

Where the index zero contains the name and the index 1 contains the Date.

But for me a better solution is to create an Object with two attributes and select this:

public class MyLatestClass {
   private String name;
   private LocalDate date;
   
   public MyLatestClass(String name, LocalDate date){
     this.name=name;
     this.date=date;
   }
   //getter 
   ....
}

interface MyClassRepository extends JpaRepository<MyClass, Long> {
    @Query(value = "select new MyLatestClass(name, max(date)) from MyClass m group by m.name")
    List<MyLatestClass> selectLatest();
}