CODEWITHSUNDEEP
javahibernatepersistenceone-to-manysql-view
Виталик Бушаев
Виталик Бушаев

Reputation: 851

hibernate map view with one to many relations

I'm mapping sql view to entity class with hibernate @Subselect annotation. Basically, it looks somewhat like this:

@Subselect(
    "SELECT table1.*, table2.id as tid FROM " 
   + "table1 INNER JOIN table2 on table2.field = table1.field"
)
@Entity
@Immutable
class Entity {
    // fields
}

When the join works i may get something like the following

========================================
| table1.id | table1.field | table2.id |
========================================
|         1 |            1 |         1 |
========================================
|         1 |            1 |         2 |
========================================

So several records in table2 can join to one row in table1. This is fine, however in java Entity I want to map it as one to many relationship(one entity to many table2 enities), here's what I wrote, which worked for others kind of relationships: 

@Subselect(
    "SELECT table1.*, table2.id as tid FROM " 
   + "table1 INNER JOIN table2 on table2.field = table1.field"
)
@Entity
@Immutable
class Entity {
    @OneToMany
    @JoinColumn(name = "tid", updatable = false, insertable = false)
    private Set<Table2Entity> elements = new HashSet<>();
}

However, the set in the entity is always empty, why is that ? The above approach works for one to one and many to one relationships.

Upvotes: 3

Views: 3292

Answers (1)

Виталик Бушаев
Виталик Бушаев

Reputation: 851

Turns, it's not required to do join with sql, to bring one to many relationship for the view entity. I solved it like this:

Subselect(
    "SELECT * from table1" 
)
@Entity
@Immutable
class Entity {
    @OneToMany
    @JoinColumn(name = "field", updatable = false, insertable = false)
    private Set<Table2Entity> elements = new HashSet<>();
}

I only needed to put column name, on which tables needed to be joined.

Upvotes: 4

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