# Migrating SDN 4.0 to SDN 6.0: Difficulties mapping @RelationshipEntity and @StartNode, @EndNode

**URL:** <https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943>\
**Category:** Spring Data Neo4j & Neo4j-OGM\
**Tags:** relationship, sdn\
**Created:** [March 26, 2021, 10:20pm UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943 "2021-03-26T22:20:37Z")\
**Posts on this page:** 5\
**Page:** 1

<div class="post-metadata">

**Author:** ![gviteri](https://sea1.discourse-cdn.com/flex021/user_avatar/community.neo4j.com/gviteri/32/7266_2.png) [@gviteri](https://community.neo4j.com/u/gviteri)\
**Post date:** [March 26, 2021, 10:20pm UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943/1 "2021-03-26T22:20:37Z")

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Hi all,  
I am having some trouble trying to migrate from SDN 4.1 to 6.0.x. We heavily use `@RelationshipEntity` with `@StartNode` and `@EndNode`, from the OGM. I have seem in the documentation and other posts that the way to go is `@RelationshipProterties` and `@TargetNode`.

I am going to put some code here and any help, advice will be extremely welcome!

OGM Implementation

```auto
@RelationshipEntity(type = "hasCandidate")
public class HasCandidate implements Comparable<HasCandidate> {
    @Id private Long id;
    @StartNode private EntitySet entitySet;
    @EndNode private PhysicalEntity physicalEntity;
    private Integer stoichiometry = 1;
    private int order;
    // getter and setters

```

Now, the class that takes the Relationship, still using the OGM implementation

```auto
@NodeEntity
public class CandidateSet extends EntitySet {
    @Relationship(type = "hasCandidate")
    private SortedSet<HasCandidate> hasCandidate;
    // any other code
}

```

Our modelling comes from a legacy code and can't be changed. So, a `CandidateSet` extends `EntitySet` and an `EntitySet` extends `PhysicalEntity`.

Now the way I am thinking with the new approach `@RelationshipProperties`

```auto
@RelationshipProperties
public class HasCandidate implements Comparable<HasCandidate> {
    @Id private Long id;
    @TargetNode private PhysicalEntity physicalEntity;
    private Integer stoichiometry = 1;
    private int order;

```

... and the class that uses `HasCandidate` relationship

```auto
@Node
public class CandidateSet extends EntitySet {

    @Relationship(type = "hasCandidate")
    private SortedSet<HasCandidate> hasCandidate;

```

and also the `@TargetNode` class has an attribute for this Relationship in the `Physical Entity` class.

```auto
@Node
public class PhysicalEntity extends DatabaseObject {
    ...
    @Relationship(type = "hasComponent", direction = Relationship.Direction.INCOMING)
    private SortedSet<HasCandidate> hasCandidate;

```

I am not so sure if this is the correct way, taking into account that `PhysicalEntity` is the `@TargetNode` and it also the superclass for `CandidateSet` and `EntitySet` ( as `@StartNode` in the previous implementation.

According to the example I need to add `Relationship.Direction.INCOMING`

Questions:

1. Is the code above correct ?
2. How do I set the name as I was doing before ?`@RelationshipEntity(type = "hasCandidate")`

Unfortunately, due to all the updates and refactoring I am doing at the moment, I can't test it, but I was wondering if this is correct and make sense.

Thanks everyone, Cheers.

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<div class="post-metadata">

**Author:** ![gerrit.meier](https://sea1.discourse-cdn.com/flex021/user_avatar/community.neo4j.com/gerrit.meier/32/27374_2.png) [@gerrit.meier](https://community.neo4j.com/u/gerrit.meier)\
**Post date:** [March 29, 2021, 5:30am UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943/2 "2021-03-29T05:30:18Z")

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There are a few adjustments left to do:

1. The `INCOMING` definition is not needed and would also wrong, if I understand your use-case correctly, because in that case a `PhysicalEntity` would have an incoming relationship to a `PhysicalEntity` and not the `CandidateSet`.
2. If you want to mimic the previous definition of the `HasCandidate`, you could also pull up the relationship definition from `CandidateSet` to `EntitySet`. In this case every derived class from `EntitySet` would have the relationship.

For the second question: the name/type is already defined correctly in the `CandidateSet` via the `@Relationship` definition. There is no need to define the type twice in SDN 6.

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<div class="post-metadata">

**Author:** ![gviteri](https://sea1.discourse-cdn.com/flex021/user_avatar/community.neo4j.com/gviteri/32/7266_2.png) [@gviteri](https://community.neo4j.com/u/gviteri)\
**Post date:** [March 29, 2021, 10:58am UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943/3 "2021-03-29T10:58:12Z")

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Thanks for your prompt reply!

1. Right, biologically speaking, a PhysicalEntity (PE) is a "roughly" a protein and we can combine them, put them together. In certain cases, a PE has to behave like a CandidateSet which contains a collection that stores all the PEs that are the candidates.

Note: In the datamodel `PhysicalEntity` is the superclass for `CandidateSet` and `EntitySet`

```auto
Ex. We have 7 PEs Nodes ( a,b,c,d,e,f,g)
For PE-a the hasCandidate list contains ( PE-b, PE-g)
For PE-f the hasCandidate list contains ( PE-b, PE-d, PE-e)

```

That's how we have the data for these relationships.

> because in that case a `PhysicalEntity` would have an incoming relationship to a `PhysicalEntity` and not the `CandidateSet` .  
> Not sure if I understood this as a `CandidateSet.hasCandidates` attribute will target `PhysicalEntity` as a node for the Relationship, am I seeing it correctly based on the new approach ?

1. OK. Yes, I got that! In our use case a `CandidateSet` has candidates (as one relationship) and the `EntitySet` which is another an superclass has members (as a relationship).  
We are following the data-model of our legacy application , which is like that,

Great. Perfect.  
Thanks

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<div class="post-metadata">

**Author:** ![gviteri](https://sea1.discourse-cdn.com/flex021/user_avatar/community.neo4j.com/gviteri/32/7266_2.png) [@gviteri](https://community.neo4j.com/u/gviteri)\
**Post date:** [March 30, 2021, 2:00pm UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943/4 "2021-03-30T14:00:04Z")

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Hey @gerrit.meier

I ran the BatchInserter (we convert a MySQL db into graph) and looks like the Relationship is working. I haven't test on the SDN repository yet but I've been doing some complex cypher that we use and they are producing the same results as before.

Thanks for your help.

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<div class="post-metadata">

**Author:** ![raviteja.bommineni](https://sea1.discourse-cdn.com/flex021/user_avatar/community.neo4j.com/raviteja.bommineni/32/28708_2.png) [@raviteja.bommineni](https://community.neo4j.com/u/raviteja.bommineni)\
**Post date:** [May 18, 2023, 5:10pm UTC](https://community.neo4j.com/t/migrating-sdn-4-0-to-sdn-6-0-difficulties-mapping-relationshipentity-and-startnode-endnode/35943/5 "2023-05-18T17:10:07Z")

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Hi @gerrit.meier,

I am also trying to migrate from SDN 4.0 to SDN 6.0.  
I heard that some annotations are removed. How to replace them with updated code with out effecting existing functionality?  
Ex annotations: Index,  
Session,  
QueryResult  
How to use properly TargetNode and RelationshipProperties in place of startNode, EndNode and RelationshipEntity.  
Could you please help me?  
Advance Thanks.