I'm using spring data mongo. I have a collection within a document that when I add an item to it I would like to assign a new automatically generated unique identifier to it e.g. (someGeneratedId)
#Document(collection = "questionnaire")
public class Questionnaire {
#Id
private String id;
#Field("answers")
private List<Answer> answers;
}
public class Answer {
private String someGeneratedId;
private String text;
}
I am aware I could use UUID.randomUUID() (wrapped in some kind of service) and set the value, I was just wondering if there was anything out of the box that can handle this? From here #Id seems to be specific to _id field in mongo:
The #Id annotation tells the mapper which property you want to use for
the MongoDB _id property
TIA
No there is no out of the box solution for generating ids for properties on embedded documents.
If you want to keep this away from your business-logic you could implement a BeforeConvertCallback which generates the id's for your embedded objects.
#Component
class BeforeConvertQuestionnaireCallback implements BeforeConvertCallback<Questionnaire> {
#Override
public Questionnaire onBeforeConvert(#NonNull Questionnaire entity, #NonNull String collection) {
for (var answer : entity.getAnswers()) {
if (answer.getId() == null) {
answer.setId(new ObjectId().toString());
}
}
return entity;
}
}
You could also implement this in a more generic manner:
Create a new annotation: #AutogeneratedId.
Then listen to all BeforeConvertCallback's of all entities and iterate through the properties with reflection. Each property annotated with the new annotation gets a unique id if null.
Related
Hi I have implemented a mock solution to my problem and I'm pretty sure something better already exist.
Here's that I want to achieve :
I have created a point to load categories with or without subCategories
/api/categories/1?fields=subCategories
returns
{
"id":"1",
"name":"test",
"subCategories":[{
"id":"1",
"name":"test123"
}]
}
/api/categories/1
returns
{
"id":"1",
"name":"test"
}
My entities
#Entity
class Category{
#Id
private String id;
private String name;
private Set<SubCategory> subCategories;
}
#Entity
class SubCategory{
#Id
private String id;
private String name;
}
I have removed services since this is not the point.
I've created CategoryDTO and SubCategoryDTO classes with the same fields as Category and SubCategory
The converter
class CategoryDTOConverter{
CategoryDTO convert(Category category,String fields){
CategoryDTO dto=new CategoryDTO();
dto.setName(category.getName());
if(StringUtils.isNotBlank(fields) && fields.contains("subCategories"){
category.getSubCategories().forEach(s->{
dto.getSubcategories().add(SubCategoryDTOConverter.convert(s));
}
}
}
}
I used com.cosium.spring.data.jpa.entity.graph.repository to create an EntityGraph from a list of attribute path
#Repository
interface CategoryRepository extends EntityGraphJpaRepository<Category, String>{
Optional<T> findById(String id,EntityGraph entityGraph);
}
Controller
#RestController
#CrossOrigin
#RequestMapping("/categories")
public class CategoryController {
#GetMapping(value = "/{id}")
public ResponseEntity<CategoryDTO> get(#PathVariable("id") String id, #RequestParam(value="fields",required=false) String fields ) throws Exception {
Optional<Category> categOpt=repository.findById(id,fields!=null?EntityGraphUtils.fromAttributePaths(fields):null);
if(categOpt.isEmpty())
throws new NotFoundException();
return ResponseEntity.ok(categoryDTOConverter.convert(categOpt.get(),fields);
}
}
This is a simple example to illustrate what I need to do
I don't want to load fields that clients doesn't want to use
How could I do this in a better way ?
Take a look at GraphQL since it is a perfect match for your use case. With GraphQL it is the client that decides which attributes it wants to receive by providing in the POST request body exactly which attributes are needed to be included in the response. This is way more manageable than trying to handle all this on your own.
Spring Boot recently added its own Spring GraphQL library, so it is quite simple to integrate it in your Spring Boot app.
I am using Spring Data's Rest Repositories from spring-boot-starter-data-rest, with Couchbase being used as the underlining DBMS.
My Pojo for the object is setup as so.
#Document
public class Item{
#Id #GeneratedValue(strategy = UNIQUE)
private String id;
#NotNull
private String name;
//other items and getters and setters here
}
And say the Item has an id of "xxx-xxx-xxx-xxx" and name of "testItem".
Problem is, that when I want to access the item, I need to be accessible by /items/testItem, but instead it is accessible by /items/xxx-xxx-xxx-xxx.
How do I get use its name instead of its generated id, to get the data.
I found out the answer to my own question.
I just need to override the config for the EntityLookup.
#Component
public class SpringDataRestCustomization extends RepositoryRestConfigurerAdapter {
#Override
public void configureRepositoryRestConfiguration(RepositoryRestConfiguration config) {
config.withEntityLookup().forRepository(UserRepository.class).
withIdMapping(User::getUsername).
withLookup(UserRepository::findByUsername);
}
}
Found the info here, though the method name changed slightly.
https://github.com/spring-projects/spring-data-examples/tree/master/rest/uri-customization
If you want query the item by name and want it perform as querying by id,you should make sure the name is unique too.You cant identify a explicit object by name if all objects have a same name,right?
With jpa you could do it like:
#NotNull
#Column(name="name",nullable=false,unique=true)
private String name;
I've the following domain and needs to return selected field in response to client. How can I achieve that using Spring?
public class Vehicle {
private String vehicleId;
private Long dateCreated;
private String ownerId;
private String colourCode;
private String engineNumber;
private String transmission;
//getters & setters
}
My objective is to return only colourCode and transmission fields to client request. I've read about DTO and seems like I can achieve my objective with DTO but I don't find any good example how to implement it. Is DTO is the correct way to achieve my objective ?
Basically you just create VehicleDTO class with parameters you need
public class VehicleDTO {
private String colourCode;
private String transmission;
//getters and setters
}
and then in your code you construct VehicleDTO from your Vehicle class. Fortunately, we have BeansUtils class from Spring, that uses reflection to copy properties of one object to another, because you do not want to repeat logic for copying properties for every object. So it would be something like:
BeanUtils.copyProperties(v1, dto);
At the end your return VehicleDTO in your response instead of Vehicle
You can return IVehicle interface which exposes your properties of choice
public interface IVehicle {
String getTransmission();
String getColourCode();
}
and your Vehicle implents it
public class Vehicle implements IVehicle{ }
There are various ways you can achieve what you want.
You can add relevant usecase / APi specific DTO for the resource.
e.g. If your API return the vehical general details you may want to expose some level of details,
public class VehicleDetailsDTO {
private String colourCode;
private String transmission;
private String engineNumber; //more
//getters and setters
}
You can then either use BeanUtils or Dozzer to convert your Vehical resource to transportable object like your DTO.
BeanUtils : http://commons.apache.org/proper/commons-beanutils/
Dozzer : http://dozer.sourceforge.net/documentation/mappings.html
Assuming you use JSON as output format and Jackson as serialization engine (default in Spring MVC), you can tell Jackson to not serialize null properties. Now you just need to populate the properties you need and can return the original business object.
I have been working in Spring Boot with the Spring Data MongoDB project and I am seeing behavior I am not clear on. I understand that the id field will go to _id in the Mongo repository per http://docs.spring.io/spring-data/mongodb/docs/current/reference/html/#mapping.conventions.id-field. My problem is that it also seems to be happening for child entities which does not seem correct.
For example I have these classes (leaving out setters and getters for brevity) :
public class MessageBuild {
#Id
private String id;
private String name;
private TopLevelMessage.MessageType messageType;
private TopLevelMessage message;
}
public interface TopLevelMessage {
public enum MessageType {
MapData
}
}
public class MapData implements TopLevelMessage {
private String layerType;
private Vector<Intersection> intersections;
private Vector<RoadSegment> roadSegments;
}
public class RoadSegment {
private int id;
private String name;
private Double laneWidth;
}
and I create an object graph using this I use the appropriate MongoRepository class to save I end up with an example document like this (with _class left out):
{
"_id" : ObjectId("57c0c05568a6c4941830a626"),
"_class" : "com.etranssystems.coreobjects.persistable.MessageBuild",
"name" : "TestMessage",
"messageType" : "MapData",
"message" : {
"layerType" : "IntersectionData",
"roadSegments" : [
{
"_id" : 2001,
"name" : "Road Segment 1",
"laneWidth" : 3.3
}
]
}
}
In this case a child object with a field named id has its mapping converted to _id in the MongoDB repository. Not the end of the world although not expected. The biggest problem is now that this is exposed by REST MVC the _id fields are not returned from a query. I have tried to set the exposeIdsFor in my RepositoryRestConfigurerAdapter for this class and it exposes the id for the top level document but not the child ones.
So circling around the 2 questions/issues I have are:
Why are child object fields mapped to _id? My understanding is that this should only happen on the top level since things underneath are not really documents in their own right.
Shouldn't the configuration to expose id fields work for child objects in a document if it is mapping the field names?
Am I wrong to think that RoadSegment does not contain a getId() ? From Spring's documentation:
A property or field without an annotation but named id will be mapped
to the _id field.
I believe Spring Data does this even to nested classes, when it finds an id field. You may either add a getId(), so that the field is named id or annotate it with #Field:
public class RoadSegment {
#Field("id")
private int id;
private String name;
private Double laneWidth;
}
I agree this automatic conversion of id/_id should only be done at the top level in my opinion.
However, the way Spring Data Mongo conversion is coded, all java ojects go through the exact same code to be converted into json (both top and nested objects):
public class MappingMongoConverter {
...
protected void writeInternal(Object obj, final DBObject dbo, MongoPersistentEntity<?> entity) {
...
if (!dbo.containsField("_id") && null != idProperty) {
try {
Object id = accessor.getProperty(idProperty);
dbo.put("_id", idMapper.convertId(id));
} catch (ConversionException ignored) {}
}
...
if (!conversions.isSimpleType(propertyObj.getClass())) {
// The following line recursively calls writeInternal with the nested object
writePropertyInternal(propertyObj, dbo, prop);
} else {
writeSimpleInternal(propertyObj, dbo, prop);
}
}
writeInternal is called on the top level object, and then recalled recursively for each subobjects (aka SimpleTypes). So they both go through the same logic of adding _id.
Perhaps this is how we should read Spring's documentation:
Mongo's restrictions on Mongo Documents:
MongoDB requires that you have an _id field for all documents. If you
don’t provide one the driver will assign a ObjectId with a generated
value.
Spring Data's restrictions on java classes:
If no field or property specified above is present in the Java class
then an implicit _id file will be generated by the driver but not
mapped to a property or field of the Java class.
I am trying to utilize a NamedEntityGraph to limit the return data for specific queries. Mainly I do not want to return full object details when listing the object. A very simple class example is below.
#Entity
#Table(name="playerreport",schema="dbo")
#NamedEntityGraphs({
#NamedEntityGraph(name = "report.simple",
attributeNodes =
{#NamedAttributeNode(value="intId")
}
)
})
public class PlayerReportEntity {
#Id
#Column(name="intid",columnDefinition="uniqueidentifier")
private String intId;
#Column(name="plyid",columnDefinition="uniqueidentifier")
#Basic(fetch=FetchType.LAZY)
private String plyId;
#ManyToOne(fetch=FetchType.LAZY)
#JoinColumn(name = "plyid", insertable=false,updatable=false)
private PlayerEntity player;
No matter what I do to plyId and player are always returned. Is there any way to only return the requested columns (intId) ?
As for the collection Hibernate does not do the join for the player object but it still returns player as null. So that part is working to an extent.
I am using a JPARepository below to generate Crud Statements for me
public interface PlayerReportRepository extends JpaRepository<PlayerReportEntity, String> {
#EntityGraph(value="report.simple")
List<PlayerIntelEntity> findByPlyId(#Param(value = "playerId") String playerId);
#Override
#EntityGraph(value="report.simple")
public PlayerIntelEntity findOne(String id);
}
A chunk of text from here - "Hence it seems that the #NamedEntityGraph only affects fields that are Collections, but fields that are not a Collection are always loaded." from JIRA
Please use the Example 47 on this page and use repositories accordingly.
In essence, hibernate is right now loading all the feilds in the class and for collections it will work if you follow the example stated above.
Thanks.