I have a Patient entity which extends a base Resource object. Now Resource contains a uuid and a display, which I also want to include to the patients table, so I annotate like so:
public class Resource implements Serializable {
#ColumnInfo
protected String uuid;
#ColumnInfo
protected String display;
// getters and setters
}
And in my Patient entity, there are nested objects and they also extend from Resource (e.g. a PatientIdentifier and a Person object is embedded and has their own uuid and display):
#Entity(tableName = "patients")
public class Patient extends Resource implements Serializable {
#PrimaryKey
private Long id;
// ...
#Embedded
private PatientIdentifier identifier;
#Embedded
private Person person;
// other variables
}
this results in a column name conflict - as there is a "uuid" column for a Patient, the PatientIdentifier and the Person.
I want to rename the nested objects' uuid columns after their name (e.g. "person_uuid"), similar to the #ForeignKey annotation in entity relationships, so may I know how to do that?
You can specify the column name like that :
#ColumnInfo(name = "person_uuid")
Related
I have a general-purpose POJO:
public class Thing {
private String name;
private String etc;
public String getName() {
return name;
}
// other getters and setters
}
I'm using Spring 4.3.9 and Spring-data-mongodb 1.10.4. I want to store instances of this POJO in Mongodb, but I have some constraints:
I can't add Spring annotations to the base class (but I can subclass Thing and annotate that).
I want to use the name field as the Mongodb unique ID (mainly to avoid creating a separate unique index for it).
I want to (redundantly) store the name field as an actual field named "name", so that other consumers of the collection don't have to know that "name" is stored in the _id.
I started out trying this:
public class SpringThing extends Thing {
#Id
#Override
public String getName() {
return super.getName();
}
#Override
public void setName(String name) {
super.setName(name);
}
}
This causes spring to use the value of name for _id, but of course it doesn't store a field named "name" in Mongodb. The documentation says that spring will use a "property or field" named "id" or annotated with #Id. So I tried defining a redundant getter/setter which accesses the name field:
public class SpringThing extends Thing {
#Id
public String getId() {
return super.getName();
}
public void setId(String id) {
super.setName(id);
}
}
Unfortunately, spring ignores getId and setId here, and stores the object with an autogenerated ID. I also tried creating redundant getters/setters annotated with #Field("name"), but spring seems to ignore any getter/setter pair without an actual field.
Adding an actual ID field and storing a copy of the name there does work:
public class SpringThing extends Thing {
#Id
private String id;
#Override
public void setName(String id) {
this.id = id;
super.setName(id);
}
}
But it requires defining a pointless field named "id".
Is there a more reasonable way to get what I want? Is what I'm trying to do reasonable to begin with?
Thanks to a hint by #mp911de, I ended up creating a subclass of Thing that looks like this:
#TypeAlias("thing")
#Document(collection = "things")
public class SpringThing extends Thing {
#Id
#AccessType(Type.PROPERTY)
#JsonIgnore
public String getId() {
return super.getName();
}
public void setId(String taskName) {
super.setName(taskName);
}
}
The #TypeAlias annotation overrides the name which spring would use for the type, to cover up the fact that I've created a subclass just to add annotations.
#Id says that this is the getter for _id.
#AccessType says to access this field through the getter and setter rather than by directly accessing the field. This is what I needed; without it, spring looks for a private member variable named something like id.
#JsonIgnore is the Jackson (JSON library that we're using) annotation to prevent including the id field when serializing these objects to JSON.
Mongodb is a no-schema document database, but in spring data, it's necessary to define entity class and repository class, like following:
Entity class:
#Document(collection = "users")
public class User implements UserDetails {
#Id private String userId;
#NotNull #Indexed(unique = true) private String username;
#NotNull private String password;
#NotNull private String name;
#NotNull private String email;
}
Repository class:
public interface UserRepository extends MongoRepository<User, String> {
User findByUsername(String username);
}
Is there anyway to use map not class in spring data mongodb so that the server can accept any dynamic JSON data then store it in BSON without any pre-class define?
First, a few insightful links about schemaless data:
what does “schemaless” even mean anyway?
“schemaless” doesn't mean “schemafree”
Second... one may wonder if Spring, or Java, is the right solution for your problem - why not a more dynamic tool, such a Ruby, Python or the Mongoshell?
That being said, let's focus on the technical issue.
If your goal is only to store random data, you could basically just define your own controller and use the MongoDB Java Driver directly.
If you really insist on having no predefined schema for your domain object class, use this:
#Document(collection = "users")
public class User implements UserDetails {
#Id
private String id;
private Map<String, Object> schemalessData;
// getters/setters omitted
}
Basically it gives you a container in which you can put whatever you want, but watch out for serialization/deserialization issues (this may become tricky if you had ObjectIds and DBRefs in your nested document). Also, updating data may become nasty if your data hierarchy becomes too complex.
Still, at some point, you'll realize your data indeed has a schema that can be pinpointed and put into well-defined POJOs.
Update
A late update since people still happen to read this post in 2020: the Jackson annotations JsonAnyGetter and JsonAnySetter let you hide the root of the schemaless-data container so your unknown fields can be sent as top-level fields in your payload. They will still be stored nested in your MongoDB document, but will appear as top-level fields when the ressource is requested through Spring.
#Document(collection = "users")
public class User implements UserDetails {
#Id
private String id;
// add all other expected fields (getters/setters omitted)
private String foo;
private String bar;
// a container for all unexpected fields
private Map<String, Object> schemalessData;
#JsonAnySetter
public void add(String key, Object value) {
if (null == schemalessData) {
schemalessData = new HashMap<>();
}
schemalessData.put(key, value);
}
#JsonAnyGetter
public Map<String, Object> get() {
return schemalessData;
}
// getters/setters omitted
}
I am totally new at this, I am sorry if it is stupid question.
I am trying to design database model for Google App Engine in JPA, but I am unable to get it right. When I find the way I can't get annotations right or I am getting error about M:N not supported in Google App Engine.
I need entity user to have multiple groups and groups have multiple users and there are users who are also group admins.
My basic model was User -> usergroup(user; group; (bool)isAdmin) <-Group
Can somebody give a clean and simple example of how to define relationships?
Please try this.
#Entity
public class User {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Key id;
private String name;
#ManyToOne(fetch = FetchType.LAZY)
private UserGroup usergroup;
}
class userGroup
#Entity
public class UserGroup {
#Id
#GeneratedValue(strategy = GenerationType.IDENTITY)
private Key id;
private String name;
private boolean admin;
#OneToMany(mappedBy = "usergroup", cascade = CascadeType.ALL)
private List<User> users = new ArrayList<User>();
}
please be noticed GAE have limitation on JPA you can read more here
I don't know anything about Google App Engine, but I can help with JPA though.
The problem here is the "isAdmin" column, which prevents the data model to be a simple #ManyToMany relationship with a joiner table.
With the introduction of this field, in the data model you need a Map on the User entity with key=Group and value=isAdmin, similarly you need a corresponding Map in the Group entity in order to know if each User is an admin.
This is modeled with #ElementCollection in the following way:
#Entity
#Table(name="User")
public class User
{
#Id
#GeneratedValue(strategy= GenerationType.TABLE)
private int id;
private String name;
#ElementCollection
#CollectionTable(name="Users_Groups", joinColumns={#JoinColumn(name="userId")})
#MapKeyJoinColumn(name="groupId")
#Column(name="isAdmin")
private Map<Group, Boolean> groups;
}
#Entity
#Table(name="Group")
public class Group
{
#Id
#GeneratedValue(strategy= GenerationType.TABLE)
private int id;
private String name;
#ElementCollection
#CollectionTable(name="Users_Groups", joinColumns={#JoinColumn(name="groupId")})
#MapKeyJoinColumn(name="userId", insertable=false, updatable=false)
#Column(name="isAdmin", insertable=false, updatable=false)
private Map<User, Boolean> users;
}
The important annotation is #ElementCollection, the other annotations are just to name the specific columns of the collection table and make sure they match from both entities: #CollectionTable gives the name of the table and the name of the column representing the id in the current entity. #MapKeyJoinColumn gives the name of the column representing the id of the "key" element in the Map, and #Column gives the name of the "value" element in the map.
I'm not sure if the insertable=false and updatable=false are needed in one of the entities, might avoid adding duplicate rows due to the cyclic dependency between User and Group.
Also you need to manually create the collection table, because at least EclipseLink tries to create it with two "groupId" and "isAdmin" columns. You might consider reviewing the design if it is absolutely needed a cyclic dependency between User and Group.
I am using JPA annotations and when i have relation OneToMany - ManyToOne, when i see my entity in the ManyToOne, the joinColumn is always with null value.
Next i will show my example, i have Product:
#Entity
#Table(name = "PC_PRODUCT")
public class Product extends LaunchEntity {
private static final long serialVersionUID = 1L;
#XmlElement(name = "Product_Name", required = true)
protected String productName;
#XmlElement(name = "Product_Description")
protected String productDescription;
#XmlElement(name = "Product_To_Charge")
#OneToMany(mappedBy = "product", cascade=CascadeType.MERGE)
protected List<ChargeRelation> productToCharge;
And, this is my ChargeRelation class:
#Entity
#Table(name="PC_CHARGE_RELATION")
public class ChargeRelation
extends RelationEntity
{
private static final long serialVersionUID = 1L;
#XmlElement(name = "Charge", required = true)
#OneToOne(cascade = CascadeType.MERGE)
protected Charge charge;
#XmlTransient
#ManyToOne(cascade=CascadeType.MERGE)
#JoinColumn(name="PRODUCT_ID")
protected Product product;
I am reading a xml file, convert data for a string, make unmarshall for my root object and persist this object.
The problem is when i found a charge relation in my string, the values are inserted on the charge relation table but the column with the product_id is always null.
I have all setters and getters defined. How i can force this to make the manual insert? thanks
Note: I'm the EclipseLink JAXB (MOXy) lead and a member of the JAXB 2 (JSR-222) expert group.
EclipseLink JAXB (MOXy) has an extension called #XmlInverseReference that allows you to map the back-pointer.
Product
#Entity
#Table(name = "PC_PRODUCT")
public class Product extends LaunchEntity {
#XmlElement(name = "Product_To_Charge")
#OneToMany(mappedBy = "product", cascade=CascadeType.MERGE)
protected List<ChargeRelation> productToCharge;
}
ChargeRelation
The #XmlInverseReference annotation is used where you previously had #XmlTransient. #XmlInverseReference acts like #XmlTransient during the marshal operation, and will populate the back-pointer during an unmarshal operation.
#Entity
#Table(name="PC_CHARGE_RELATION")
public class ChargeRelation extends RelationEntity {
#XmlInverseReference(mappedBy = "productToCharge")
#ManyToOne(cascade=CascadeType.MERGE)
#JoinColumn(name="PRODUCT_ID")
protected Product product;
}
For More Information
http://blog.bdoughan.com/2010/07/jpa-entities-to-xml-bidirectional.html
http://blog.bdoughan.com/2011/05/specifying-eclipselink-moxy-as-your.html
Note that JPA provider reflects the state of many-to-one side of relationship when saving it to the database.
However, JAXB only populates one-to-many side during XML unmarshalling, therefore you need to populate many-to-one side manually after unmarshalling.
first post here, hoping someone could perhaps shed some light on an issue I've been trying to juggle...
As a part of a school project we're attempting to build a interface to display points on a map and paths on a map.
For our first sprint I managed to work out storing/retrieving items using Objectify - it went great!
Now we're trying to extend the functionality for our next spring. Having problems now trying to store an object of type MapPath (note MapPath and MapData, our two data types, both extend class Data). Brief code snippets as follows :
#Entity
public class Data extends JavaScriptObject
{
#Id
Long id;
private String name;
private String dataSet;
...getters and setters
}
#Subclass
public class MapData extends Data implements Serializable{
{
private String name;
private String address;
private String dataSet;
#Embedded
private Coordinate location;
....constructors, getters/setters
}
#Subclass
public class PathData extends Data implements Serializable{
private String name;
private String address;
private String dataSet;
#Embedded
private Coordinate[] path;
...etc
}
Now hopefully I haven't lost you yet. I have a DataService class that basically handles all transactions. I have the following unit test :
#Test
public void storeOnePath(){
PathData pd = new PathData();
pd.setName("hi");
DataService.storeSingleton(pd);
Data d = DataService.getSingleton("hi");
assertEquals(pd,d);
}
The implementation of getSingleton is as follows :
public static void storeSingleton(Data d){
Objectify obj = ObjectifyService.begin();
obj.put(d);
}
JUnit complains:
java.lang.ExceptionInInitializerError
at com.teamrawket.tests.DataTest.storeOnePath(DataTest.java:59)
...<taken out>
Caused by: java.lang.IllegalStateException: Attempting to create multiple associations on class com.teamrawket.server.MapData for name
at com.googlecode.objectify.impl.Transmog$Visitor.addRootSetter(Transmog.java:298)
at com.googlecode.objectify.impl.Transmog$Visitor.visitField(Transmog.java:231)
at com.googlecode.objectify.impl.Transmog$Visitor.visitClass(Transmog.java:134)
at com.googlecode.objectify.impl.Transmog.<init>(Transmog.java:319)
at com.googlecode.objectify.impl.ConcreteEntityMetadata.<init>(ConcreteEntityMetadata.java:75)
at com.googlecode.objectify.impl.Registrar.registerPolymorphicHierarchy(Registrar.java:128)
at com.googlecode.objectify.impl.Registrar.register(Registrar.java:62)
at com.googlecode.objectify.ObjectifyFactory.register(ObjectifyFactory.java:209)
at com.googlecode.objectify.ObjectifyService.register(ObjectifyService.java:38)
at com.teamrawket.server.DataService.<clinit>(DataService.java:20)
... 27 more
What exactly does "attempting to create multiple associations on class ... for name" imply?
Sorry for the long post and any formatting issues that may arise.
You have repeated field names in your subclasses. You should not declare 'name' and 'dataSet' in both superclasses and subclasses; remove these fields from MapData and PathData and you should be fine.
com.teamrawket.server.MapData refers to the fullPath name for your MapData file. The name at the end refers to the field String name in your MapData class. This whole exception tries to tell you that it already contains a reference for that specific fullPath.
I would say there is another object with the same fullPath already registered. It would be helpful to know where line 59 is exactly as that is where the error occured.