Hey everyone I am fairly new to Neo4j and am having an issue querying my repositories.
Repository is the follow:
public interface NodeOneRepository extends GraphRepository<NodeOne> {
List<NodeOne> findByNodeTwoNodeThreeAndActiveTrue(NodeThree nodeThree);
}
My entities are the following:
#NodeEntity(label = "NodeOne")
public class NodeOne {
#GraphId
private Long id;
private Boolean active = TRUE;
#Relationship(type = "IS_ON")
private NodeTwo nodeTwo;
}
#NodeEntity(label = "NodeTwo")
public class NodeTwo {
#GraphId
private Long id;
#Relationship(type = "CONTAINS", direction = "INCOMING")
private NodeThree nodeThree;
#Relationship(type = "IS_ON", direction = "INCOMING")
private List<NodeOne> nodeOnes = new ArrayList<>();
}
#NodeEntity(label = "NodeThree")
public class NodeThree {
#GraphId
private Long id;
#Relationship(type = "CONTAINS")
private List<NodeTwo> nodeTwos = new ArrayList<>();
}
Getters & Setters omitted. When I call the method I get an empty list. Is there something I am doing incorrectly?
You didn't describe exactly what you wanted to achieve, but I can see two problems:
Problem 1:
The current version of Spring Data Neo4j and OGM only allow nested finders, that is, finders that specify a relationship property, to one depth.
Supported
findByNodeTwoSomePropertyAndActiveTrue(String relatedNodePropertyValue)
Not Supported
findByNodeTwoNodeThree //Nesting relationships in finders is not supported
Problem 2:
Derived Finders Allow Matching Properties and Nested Properties. Not a whole instance of that class.
You can probably achieve what you would like using a custom query.
#Query("custom query here")
List<NodeOne> findByNodeTwoNodeThreeAndActiveTrue(NodeThree nodeThree);
If you need help to write a custom query, you can post another question or join the neo4j-users public slack channel.
Related
I am trying to input few graph nodes in neo4j db using spring-data-neo4j.
Nodes are having the following relationship.
Project -> Cluster -> Entity -> Methods and Entity node has relationship with its ownn, making it bidirectinoal relationship.
Entity class is defined as follows.
#JsonIdentityInfo(generator = ObjectIdGenerators.PropertyGenerator.class,
property = "id")
#NodeEntity
public class Entity {
public int id;
public String type;
public String name;
public String entityId;
Public String projectId;
#Relationship(type = "CONNECTS_TO", direction = Relationship.INCOMING)
private Set<Entity> entityIdr;
}
Below error is thrown while trying to insert Cluster and Entity nodes, what could be possible resolution to avoid following ?
com.fasterxml.jackson.databind.JsonMappingException: Infinite
recursion (StackOverflowError) (through reference chain:
I assume that you try to serialize the data and expose it on the web layer or similar, right?
The jackson serialization needs to get more informations on how to break the cycles the Java data model describes.
So either you ignore a property with #JsonIgnore like
#JsonIgnore
#Relationship(type = "CONNECTS_TO", direction = Relationship.INCOMING)
private Set<Entity> entityIdr;
, but that seems at least for the first level like a loss of information,
or
#JsonIgnoreProperties("entityIdr")
#Relationship(type = "CONNECTS_TO", direction = Relationship.INCOMING)
private Set<Entity> entityIdr;
We wrote this up in the documentation for Neo4j-OGM: https://neo4j.com/docs/ogm-manual/current/reference/#_a_note_on_json_serialization
I'd like to find all Offer documents by Offer.ProductProperties.brand:
#Document(collection = "offers")
public class Offer {
#Id
private String id;
#NotNull
#DBRef
private ProductProperties properties;
ProductProperties:
#Document(collection = "product_properties")
public class ProductProperties {
#Id
private String id;
#NotNull
#NotEmpty
private String brand;
Service:
Flux<ProductProperties> all = productPropertiesRepository.findAllByBrand(brand);
List<String> productPropIds = all.toStream()
.map(ProductProperties::getId)
.collect(Collectors.toList());
Flux<Offer> byProperties = offerRepository.findAllByProperties_Id(productPropIds);
But unfortunately byProperties is empty. Why?
My repository:
public interface OfferRepository extends ReactiveMongoRepository<Offer, String> {
Flux<Offer> findAllByProperties_Id(List<String> productPropertiesIds);
}
How to find all Offers by ProductProperties.brand?
Thanks!
After reading some documentation found out that You cannot query with #DBRef. Hence the message
Invalid path reference properties.brand! Associations can only be
pointed to directly or via their id property
If you remove DBRef from the field, you should be able to query by findAllByProperties_BrandAndProperties_Capacity.
So the only ways is how you are doing. i.e. Fetch id's and query by id.
As I said in the comment, the reason it is not working is because return type of findAllByProperties_Id is a Flux. So unless u execute a terminal operation, you wont have any result. Try
byProperties.collectList().block()
I have a database service using Spring Boot 1.5.1 and Spring Data Rest. I am storing my entities in a MySQL database, and accessing them over REST using Spring's PagingAndSortingRepository. I found this which states that sorting by nested parameters is supported, but I cannot find a way to sort by nested fields.
I have these classes:
#Entity(name = "Person")
#Table(name = "PERSON")
public class Person {
#ManyToOne
protected Address address;
#ManyToOne(targetEntity = Name.class, cascade = {
CascadeType.ALL
})
#JoinColumn(name = "NAME_PERSON_ID")
protected Name name;
#Id
protected Long id;
// Setter, getters, etc.
}
#Entity(name = "Name")
#Table(name = "NAME")
public class Name{
protected String firstName;
protected String lastName;
#Id
protected Long id;
// Setter, getters, etc.
}
For example, when using the method:
Page<Person> findByAddress_Id(#Param("id") String id, Pageable pageable);
And calling the URI http://localhost:8080/people/search/findByAddress_Id?id=1&sort=name_lastName,desc, the sort parameter is completely ignored by Spring.
The parameters sort=name.lastName and sort=nameLastName did not work either.
Am I forming the Rest request wrong, or missing some configuration?
Thank you!
The workaround I found is to create an extra read-only property for sorting purposes only. Building on the example above:
#Entity(name = "Person")
#Table(name = "PERSON")
public class Person {
// read only, for sorting purposes only
// #JsonIgnore // we can hide it from the clients, if needed
#RestResource(exported=false) // read only so we can map 2 fields to the same database column
#ManyToOne
#JoinColumn(name = "address_id", insertable = false, updatable = false)
private Address address;
// We still want the linkable association created to work as before so we manually override the relation and path
#RestResource(exported=true, rel="address", path="address")
#ManyToOne
private Address addressLink;
...
}
The drawback for the proposed workaround is that we now have to explicitly duplicate all the properties for which we want to support nested sorting.
LATER EDIT: another drawback is that we cannot hide the embedded property from the clients. In my original answer, I was suggesting we can add #JsonIgnore, but apparently that breaks the sort.
I debugged through that and it looks like the issue that Alan mentioned.
I found workaround that could help:
Create own controller, inject your repo and optionally projection factory (if you need projections). Implement get method to delegate call to your repository
#RestController
#RequestMapping("/people")
public class PeopleController {
#Autowired
PersonRepository repository;
//#Autowired
//PagedResourcesAssembler<MyDTO> resourceAssembler;
#GetMapping("/by-address/{addressId}")
public Page<Person> getByAddress(#PathVariable("addressId") Long addressId, Pageable page) {
// spring doesn't spoil your sort here ...
Page<Person> page = repository.findByAddress_Id(addressId, page)
// optionally, apply projection
// to return DTO/specifically loaded Entity objects ...
// return type would be then PagedResources<Resource<MyDTO>>
// return resourceAssembler.toResource(page.map(...))
return page;
}
}
This works for me with 2.6.8.RELEASE; the issue seems to be in all versions.
From Spring Data REST documentation:
Sorting by linkable associations (that is, links to top-level resources) is not supported.
https://docs.spring.io/spring-data/rest/docs/current/reference/html/#paging-and-sorting.sorting
An alternative that I found was use #ResResource(exported=false).
This is not valid (expecially for legacy Spring Data REST projects) because avoid that the resource/entity will be loaded HTTP links:
JacksonBinder
BeanDeserializerBuilder updateBuilder throws
com.fasterxml.jackson.databind.exc.MismatchedInputException: Cannot construct instance of ' com...' no String-argument constructor/factory method to deserialize from String value
I tried activate sort by linkable associations with help of annotations but without success because we need always need override the mappPropertyPath method of JacksonMappingAwareSortTranslator.SortTranslator detect the annotation:
if (associations.isLinkableAssociation(persistentProperty)) {
if(!persistentProperty.isAnnotationPresent(SortByLinkableAssociation.class)) {
return Collections.emptyList();
}
}
Annotation
#Retention(RetentionPolicy.RUNTIME)
#Target(ElementType.FIELD)
public #interface SortByLinkableAssociation {
}
At project mark association as #SortByLinkableAssociation:
#ManyToOne
#SortByLinkableAssociation
private Name name;
Really I didn't find a clear and success solution to this issue but decide to expose it to let think about it or even Spring team take in consideration to include at nexts releases.
Please see https://stackoverflow.com/a/66135148/6673169 for possible workaround/hack, when we wanted sorting by linked entity.
is it possible to have a projection with nested collection with Spring JPA?
I have the following 2 simple entity (to explain the problem)
#Entity
#Table(name = "person")
public class Person implements Serializable {
private Integer id;
private String name;
#OneToMany
private List<Address> addressList = new ArrayList<>();
}
#Entity
#Table(name = "address")
public class Address implements Serializable {
private Integer id;
private String city;
private String street;
}
Is it possible to have a projection of Person with following attributes filled in ? {person.name, address.city}
I might be wrong in semantics of word Projection. but the problem is what i need to achieve. Maybe it is not possible with Projection, but is there another way to achieve the end goal? Named Entity graph perhaps ?
P.S. please suggest a solution for Spring JPA not Spring Jpa REST
thanks in advance
You're right, Entity Graphs serve this exact purpose - control field loading.
Create entity graphs dynamically from the code or annotate target entities with Named Entity Graphs and then just use their name.
Here is how to modify your Person class to use Named Entity Graphs:
#Entity
#Table(name = "person")
#NamedEntityGraph(name = "persion.name.with.city",
attributeNodes = #NamedAttributeNode(value = "addressList", subgraph = "addresses.city"),
subgraphs = #NamedSubgraph(name = "addresses.city", attributeNodes = #NamedAttributeNode("city")))
public class Person implements Serializable {
private Integer id;
private String name;
#OneToMany
private List<Address> addressList;
}
And then when loading your person:
EntityGraph graph = em.getEntityGraph("person.name.with.city");
Map hints = new HashMap();
hints.put("javax.persistence.fetchgraph", graph);
return em.find(Person.class, personId, hints);
The same applies for queries, not only em.find method.
Look this tutorial for more details.
I think that that's not usual scenario of Data JPA usage. But you can achieve your goal with pure JPQL:
SELECT a.street, a.person.name FROM Address a WHERE …
This solution has 2 drawbacks:
It forces you to have bidirectional relationship Address ←→ Person
It returns List
Another solution (and that's preferred JPA way) is to create DTO like this:
class MyPersonDTO {
private String personName;
private List<String> cities;
public MyPersonDTO(String personName, List<Address> adresses) {
this.personName = personName;
cities = adresses
.stream()
.map(Address::getCity)
.collect(Collectors.toList());
}
}
And the execute JPQL query like this:
SELECT NEW package.MyPersonDTO(p.name, p.addressList) FROM Person p WHERE …
Return type will be List<MyPersonDTO> in that case.
Of course you can use any of this solutions inside #Query annotation and it should work.
I am trying to create a query using hibernate following the example given in section 9.2 of chapter 9
The difference with my attempt is I am using spring MVC 3.0. Here is my Address class along with the method i created.
#RooJavaBean
#RooToString
#RooEntity
#RooJson
public class Address {
#NotNull
#Size(min = 1)
private String street1;
#Size(max = 100)
private String street2;
private String postalcode;
private String zipcode;
#NotNull
#ManyToOne
private City city;
#NotNull
#ManyToOne
private Country country;
#ManyToOne
private AddressType addressType;
#Transient
public static List<Tuple> jqgridAddresses(Long pID){
CriteriaBuilder builder = Address.entityManager().getCriteriaBuilder();
CriteriaQuery<Tuple> criteria = builder.createTupleQuery();
Root<Address> addressRoot = criteria.from( Address.class );
criteria.multiselect(addressRoot.get("id"), addressRoot.get("street1"), addressRoot.get("street2"));
criteria.where(builder.equal(addressRoot.<Set<Long>>get("id"), pID));
return Address.entityManager().createQuery( criteria ).getResultList();
}
}
The method called jqgridAddresses above is the focus. I opted not to use the "Path" because when I say something like Path idPath = addressRoot.get( Address_.id ); as in section 9.2 of the documentation, the PathAddress_.id stuff produces a compilation error.
The method above returns an empty list of type Tuple as its size is zero even when it should contain something. This suggests that the query failed. Can someone please advise me.
OK so i made some minor adjustments to my logic which is specific to my project, however, the following approach worked perfectly. Hope it hepls someone in need !
#Transient
public static List<Tuple> jqgridPersons(Boolean isStudent, String column, String orderType, int limitStart, int limitAmount){
CriteriaBuilder builder = Person.entityManager().getCriteriaBuilder();
CriteriaQuery<Tuple> criteria = builder.createTupleQuery();
Root<Person> personRoot = criteria.from(Person.class );
criteria.select(builder.tuple(personRoot.get("id"), personRoot.get("firstName"), personRoot.get("lastName"), personRoot.get("dateOfBirth"), personRoot.get("gender"), personRoot.get("maritalStatus")));
criteria.where(builder.equal( personRoot.get("isStudent"), true));
if(orderType.equals("desc")){
criteria.orderBy(builder.desc(personRoot.get(column)));
}else{
criteria.orderBy(builder.asc(personRoot.get(column)));
}
return Address.entityManager().createQuery( criteria ).setFirstResult(limitStart).setMaxResults(limitAmount).getResultList();
}