I want to add a Relationship between two already existing nodes in Neo4j - how to do that using Spring Data Neo4jRepository? - neo4j

Question

The cypher query to perform the above task would be as follows:
MATCH (a:Buyer), (b:Seller)
MERGE (a) -[:BUY {quantity: 150}]-> (b);
I want the equivalent Neo4jRepository function or some equivalent code that can serve the same above purpose. Please post the answer if you know some solution.
[Updates]
I have posted an answer below. But I am also expecting some other kind of solutions to this purpose. Please feel free to post alternative solutions as answers.

Answer 1

One Possible Way
If we have two Nodes/Entities as Buyer and Stock as POJO classes in SpringBoot Code, and if we are trying to add a relationship called [:HAS] between two such nodes then we can do the following.
#Node("Stock")
class Stock
{
#Id #GeneratedValue(...)
private Long id;
/* Other attributes here --- */
}
#Node("Buyer")
class Buyer
{
#Id #GeneratedValue(...)
private Long id;
/* Other Attribute Variables Here --- */
#Relationship(type="HAS")
private List<Stock> stockList;
public List<Stock> getStockList()
{
return stockList;
}
public void setStockList(List stockList)
{
this.stockList = stockList;
}
}
So we can do this to create the desired relationship.
buyer.getStockList().add(newStock);
buyerRepo.save(buyer);
Here buyerRepo is the object of a Repository that implements Neo4jRepository<Buyer, Long>