How can you map a property to a specific column of another table using JPA?

Question

I have two tables. One has the data I'm concerned about, "Thing". Thing schema:

• thing_id
• name
• thing_type_id
• ...metadata (including created and modified dates)

'thing_type_id' is a foreign key for another table, which is basically acting as an enum.

ThingType schema:

• thing_type_id
• name
• ...metadata

I have created classes for both, and I can easily join the two using

@ManyToOne() @JoinColumn(name = "thing_type_id") private ThingType thingType;

to associate a ThingType object with each Thing. However, the only relevant field is ThingType.name.

What I want to do is reference the string directly, like

@Column(table = "thing_type" name="name") private String thingType;

Approaches I've tried

• Using the @SecondaryTable annotation on the Thing class seems to only work for one-to-one mapping.
• @JsonIgnore on all irrelevant fields of ThingType leaves me with an object containing only one entry rather than just the value of that entry.
• Joining the whole object as above, @JsonIgnoring it, and create a getter to that field that somehow maps to the JSON output should work, but I'm not sure how to do that.

Thank you for your help!

Answer 1

Figured it out. The third approach works.

@JsonIgnore @ManyToOne() @JoinColumn(name = "thing_type_id") private ThingType thingType;

@JsonProperty("thingType") String getThingType() { return this.thingType.getName(); }