java - How to create a model, in Spring, from json where the foreign key is referenced as a long attribute? -
one group has many users:
group
import com.fasterxml.jackson.annotation.jsonignore; import com.fasterxml.jackson.annotation.jsonmanagedreference; import javax.persistence.*; import java.util.collection; import java.util.list; @entity @table(name = "groups") public class group { @id @column(name = "id") private long id; @column(name = "name") private string name; //@jsonmanagedreference @onetomany(mappedby = "group" //, fetch = fetchtype.eager //, cascade = cascadetype.all ) private list<users> itsuser; //getters , setters omitted clarity } users
import com.fasterxml.jackson.annotation.jsonbackreference; import com.fasterxml.jackson.annotation.jsonignore; import com.fasterxml.jackson.annotation.jsonmanagedreference; import com.fasterxml.jackson.annotation.jsonproperty; import javax.persistence.*; import static javax.persistence.generationtype.sequence; @entity @table(name = "users") @sequencegenerator(name = "sequence_user_id", //my own name in java (unique) sequencename = "generator_sequence_users", //in database initialvalue = 1, allocationsize = 1) public class users { @jsonproperty(value = "id") //these play role when both reading or writing @id @column(name = "id") @generatedvalue(strategy=sequence, generator="sequence_user_id") private long id; @jsonproperty(value = "name") @column(name="name") private string name; @jsonproperty(value = "username") @column(name="username") private string username; @jsonproperty(value = "password") @column(name="password") private string password; @jsonproperty(value = "email") @column(name="email") private string email; @jsonproperty(value = "picture") //now works both mypic , picture json keys @column(name="picture") private string picture; //@column(name="group_id") //we have manytoone this, cannot repeat @jsonproperty(value = "groups_id") //to ignore in jpa (http://stackoverflow.com/questions/1281952/jpa-fastest-way-to-ignore-a-field-during-persistence) private long itsgroupid; @transient public long getitsgroupid() { if(itsgroupid == null) { this.itsgroupid = group.getid(); } else { //nop } return itsgroupid; } public void setitsgroupid(long itsgroupid) { this.itsgroupid = itsgroupid; } //@jsonignore //@jsonproperty(value = "groups_id") //@jsonbackreference @manytoone(optional = false, targetentity = group.class) @joincolumn( name = "group_id", //column name referencedcolumnname = "id" //reference name ) private group group; //getters , setters omitted clarity } we using spring spring-data , jackson things automagically cannot configure magic:
we trying stick on following constraints @ same time:
1) keep ability have reference groupid , manytoone relationship group.
easy achieved putting @transient annotation @ groupid because @column not allowed since have declared @manytoone annotation. have implement getgroupid method accordingly.
2) return json of users class contains groups_id.
can implemented setting @jsonproperty annotation.
3) create user class, , save in database, json. json contains groups_id has value integer foreign key.
not work because setting @transient above, system refuses save in database transient or @ least how interpret exception:
http status 500 - request processing failed; nested exception org.springframework.dao.dataintegrityviolationexception: not-null property references null or transient value: com.pligor.mvctest.models.users.group; nested exception org.hibernate.propertyvalueexception: not-null property references null or transient value: com.pligor.mvctest.models.users.group
on backend this:
group group = grouprepository.findbyid(userresource.getgroupid()); if (group != null) { user user = new user(userresource); user.setgroup(group); userrepository.save(); } the idea behind need fetch group db, able link newly created user
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