Hi everybody,
I am making a project for Group Chat which has following domain objects. What I want is that the orderId of CommentPK get auto incremented with respect to the groupId provided. If I use method like GenerationType.Table, pkColumnName="max_id_name", pkColumnValue="max_comment_id", valueColumnName="max_id" then the orderId will be globally unique which will also limit the maximum number of comments the system supports as the key "max_comment_id" is a constant. Instead I want to use a pkColumnValue which can be derived from the groupId supplied eg. say for group 1 the key is max_comment_group_1, for group 2 let the key be "max_comment_group_2". I want to use only JPA specs for this such that I can give variable value for pkColumnValue field in @TableGenerator. But any hibernate specific solution will also do.
Code:
@Entity
class Group
{
@Id @GeneratedValue(strategy=GenerationType.IDENTITY)
long id;
String name;
}
@Entity
class User
{
@TableGenerator(
name="max_ids_generator",
table="max_ids",
pkColumnName="max_id_name",
pkColumnValue="max_user_id",
valueColumnName="max_id",
initialValue=1,
allocationSize=1
)
@Id
@GeneratedValue(strategy=GenerationType.TABLE, generator="max_ids_generator")
long id;
long name;
}
@Embeddable
class CommentPK
{
long groupId;
long orderId; // this is the ordering of the comment, Eg. 1st comment, 2nd comment for the provided groupId.
}
@Entity
class Comment
{
@EmbeddedId
CommentPK commentId;
long userId;
String comment;
}
Thanks in advance.
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