Unfetched attribute error when loading an instance name in case of entities hierarchy

[gorbunkov]

Environment

Jmix version: 2.1.3

Bug Description

Let's say that we have a Pet entity:

@JmixEntity
@Table(name = "PET")
@Entity
public class Pet {
    @JmixGeneratedValue
    @Column(name = "ID", nullable = false)
    @Id
    private UUID id;

    @Column(name = "NAME")
    private String name;

    @Column(name = "SECOND_NAME")
    private String secondName;

// getters and setters
 
    @InstanceName
    @DependsOnProperties({"name"})
    public String getInstanceName(MetadataTools metadataTools) {
        return metadataTools.format(name);
    }
}

It has a descendant class:

@JmixEntity
@Entity
public class Dog extends Pet {
    @Column(name = "DOG_NAME")
    private String dogName;

// getters and setters

    @InstanceName
    @DependsOnProperties({"dogName"})
    public String getInstanceName(MetadataTools metadataTools) {
        return metadataTools.format(dogName);
    }
}

Dog's instance name contains attribute that is not present in Pet.

The Appointment entity has a reference to Pet:

@JmixEntity
@Table(name = "APPOINTMENT", indexes = {
        @Index(name = "IDX_APPOINTMENT_PET", columnList = "PET_ID")
})
@Entity
public class Appointment {
    @JmixGeneratedValue
    @Column(name = "ID", nullable = false)
    @Id
    private UUID id;

    @Column(name = "DATE_")
    private LocalDate date;

    @JoinColumn(name = "PET_ID")
    @ManyToOne(fetch = FetchType.LAZY)
    private Pet pet;

// getters and setters
}

The problem is that when we load a list of appointments in the appointments list view the error appears:

IllegalStateException: Cannot get unfetched attribute [dogName] from detached object com.company.instancenameissue.entity.Dog-31fd51d1-b51f-1c7c-459e-a4fb4275a224 [detached].

Fetch plan for Appointment contains a Pet attribute (it doesn't contain a dogName flield that is used by dog instance name). But the screen tries to evaluate an actual instance name (for Dog) instead of evaluating instance name for Pet.

The solution may be to introduce a new method in the InstanceNameProvider that in addition to entity instance will accept the class that should be used for instance name evaluation (we would pass Pet.class there). This new method should be somehow used by Jmix dataGrids and other components.

Sample Project

instanceNameIssue.zip

[dtaimanov]

The same issue is also caused these problems: https://forum.jmix.io/t/missing-childfield-on-association/3043

Subclass instances loaded by reference with superclass type have unfetched local fields when BASE fetch plan used. Unfortunately the only workaround is to reload entities by ids because properties defined in subclasses neither loaded automatically, nor can be specified in fetch plan.

Suggested solution:
Rework fetch plan processing in order to allow fields from subclasses and/or translate standard fetch plans correctly covering all possible fields.