Spring Data Rest - resource becomes unavailable when subclassed - spring

Question

After having debugged my head off, I am out of ideas and would need some help. What really intrigues me badly is the simplicity of what I am trying to do and still the impossibility of achieving it...
I am trying to make a small demo of spring rest data, by creating some entities, exposing them as rest resources and persisting them in an in-memory h2 database.
The following code works:
#Entity
#Table(name="info")
#Inheritance(strategy = InheritanceType.SINGLE_TABLE)
#DiscriminatorColumn(name="INFO_TYPE", discriminatorType=DiscriminatorType.STRING)
public class ItemInfo {
#Id
#GeneratedValue(strategy = GenerationType.AUTO)
#Column(name = "id")
public long id;
public long getId() {
return id;
}
public void setId(long id) {
this.id = id;
}
}
#RepositoryRestResource(collectionResourceRel="itemInfos", path="itemInfos")
public interface ItemInfoRepository extends PagingAndSortingRepository<ItemInfo, Long> {
}
When I issue a curl request for curl http://localhost:8080/itemInfos I get the following correct response:
{
"_embedded" : {
"itemInfos" : [ ]
},
"_links" : {
"self" : {
"href" : "http://localhost:8080/itemInfos"
},
"profile" : {
"href" : "http://localhost:8080/profile/itemInfos"
}
},
"page" : {
"size" : 20,
"totalElements" : 0,
"totalPages" : 0,
"number" : 0
}
}
However, as soon as I add a subclass entity of ItemInfo, the /itemInfos resource will not be available anymore.
So adding the class:
#Entity
#Table(name="info")
#DiscriminatorValue(value="COMMENT")
public class UserComment extends ItemInfo {
private String from;
private String comment;
public String getFrom() {
return from;
}
public void setFrom(String from) {
this.from = from;
}
public String getComment() {
return comment;
}
public void setComment(String comment) {
this.comment = comment;
}
}
Will result in the same curl command as earlier to produce an error:
{"timestamp":1488282548770,"status":500,"error":"Internal Server Error","exception":"org.springframework.dao.InvalidDataAccessResourceUsageException","message":"could not prepare statement; SQL [select iteminfo0_.id as id2_0_, iteminfo0_.comment as comment3_0_, iteminfo0_.from as from4_0_, iteminfo0_.info_type as info_typ1_0_ from info iteminfo0_ limit ?]; nested exception is org.hibernate.exception.SQLGrammarException: could not prepare statement","path":"/itemInfos"}
Furthermore, trying to add a new itemInfo causes a similar error:
{"timestamp":1488282718547,"status":500,"error":"Internal Server Error","exception":"org.springframework.dao.InvalidDataAccessResourceUsageException","message":"could not prepare statement; SQL [insert into info (id, info_type) values (null, 'ItemInfo')]; nested exception is org.hibernate.exception.SQLGrammarException: could not prepare statement","path":"/itemInfos"}
Adding a UserCommentRepository also doesn't solve the problem in any way:
public interface UserCommentRepository extends PagingAndSortingRepository<UserComment, Long> { }
In this case, if i try to add a new user comment:
curl -i -X POST -H "Content-Type:application/json" -d "{ \"from\" : \"Ana\", \"comment\" : \"some comment\" }" http://localhost:8080/userComments
I get a further error:
{"timestamp":1488282968879,"status":500,"error":"Internal Server Error","exception":"org.springframework.dao.InvalidDataAccessResourceUsageException","message":"could not prepare statement; SQL [insert into info (id, comment, from, info_type) values (null, ?, ?, 'COMMENT')]; nested exception is org.hibernate.exception.SQLGrammarException: could not prepare statement","path":"/userComments"}
It seems that adding inheritance for my entities completely ruins my resources. Did anyone of you had a similar problem?!

Answer 1

Ok...I figured it out (mostly by mistake) and it is even more frustrating.
The problem was the use of the variable name "from". It seems that spring data rest uses this as a keyword. As soon as I refactored the name of this variable, everything worked as expected. Unfortunately the exceptions and error messages didn't help at all.
Hopefully others will not go through the same debugging hell...