Neo4j Connection Problem: API Error

[Mtmmmmm]

I can build up the connection between Neo4j and R. However, I got an error message when I call the API. Below is an example of the error when I tried to run a Cypher query pulling data.

> library(neo4r)
> library(magrittr)
> con <- neo4j_api$new(url = "http://localhost:7474", 
+                      user = "xxx", password = "xxx")
> 
> con$ping()
[1] 401
> 
> 'MATCH (p:Person) -[r:ACTED_IN] -> (m:Movie) RETURN *;' %>%
+   call_neo4j(con, output = "json")
Error: API error

Thanks in advance.

[ColinFay]

Hey,

It seems that the API returns an error when you ping it (https://neo4j.com/docs/http-api/current/http-api/security/#http-api-missing-authorization)

Are you sure you're providing the right auth elements?

[Mtmmmmm]

Hi Colin,

Thanks for your quickly reply. I confirmed that the error was due to the wrong auth, sorry for the confusion.

As I am new to neo4j, I have 2 questions would like to ask:

1. Now I have the connection built up, however, I still have error messages when querying data from Neo4j API. I am using Movie dataset in Neo4j and below is the code and error.

> res1 <- 'MATCH (p:Person) -[r:ACTED_IN] -> (m:Movie) RETURN p.name, m.title;' %>% 
+   call_neo4j(con)
Error in names(object) <- nm : 
  'names' attribute [2] must be the same length as the vector [1]
> 
> res2 <- 'MATCH (p:Person) -[r:ACTED_IN] -> (m:Movie) RETURN *;' %>% 
+   call_neo4j(con)
Error in cbind_all(x) : Argument 6 must be length 1, not 3
> 
> res3 <- 'MATCH (p:Person) -[r:ACTED_IN] -> (m:Movie) WHERE p.name = "Tom Hanks" RETURN *;' %>% 
+   call_neo4j(con)
Error in cbind_all(x) : Argument 6 must be length 1, not 6

As above, I tried to extract data in 3 different ways that I will be using for my ongoing project, they all have error messages. I assume that is because different types of nodes have different number of records (eg. 1 movie can contain multiple actors, this leads the error in res1)

The only way worked for me was to specify type = "graph" when calling the API.

2. I know we can create new elements in Neo4j by sending cypher query back using PASTE/SEND_ CYPHER, I am a bit stuck on the syntax by following the examples in neo4r document. I am wondering how can I create new nodes and merge them with existing nodes by creating new relationships in R. Ideally, I would like to create those new elements by specifying constraints, labels and properties in R statement and have them automatically writing back to Neo4j database.

Thank you so much!