How to add unique data to a neo4j graph database - neo4j

Question

I am adding iteratively data to my neo4j database but I am stuck with how to overwrite or update existing data and to check whether the data does not already exist in there.
Basically I have a set of movies with their corresponding id's, e.g.:
[
{id: 'gameofthrones', genre: 'fantasy', release: '2017'},
{id: 'inception', genre: 'scifi', release: '2010'},
...
]
I can add the movies as follows:
CREATE
(m1:Movie {id: 'gameofthrones', genre: 'fantasy', release: '2017'}),
(m2:Movie {id: 'inception', genre: 'scifi', release: '2010'})
However, when I run the script two times, then it creates 4 nodes instead of keeping it at two nodes.
So my question is, how can I make sure that it checks whether the node id is already present, and if so overwrite it instead of creating a new node?
I tried (but only the properties get added)
// data
attributes['id'] = 'gameofthrones';
attributes['genre'] = 'fantasy';
...
// query
MERGE ( s:Movie {attributes}.id)
ON CREATE SET ( s:Movie {attributes} )
which I call in NodeJS as follows:
executeQuery(queryStr, {"attributes": attributes})
// cypher (nodejs)
function executeQuery(queryStr, params) {
var qq = Q.defer();
db.cypher({
query: queryStr,
params: params,
}, function (error, results) {
if (error) {
qq.reject(error);
} else {
if (results.length != 0) {
qq.resolve(true);
} else {
qq.resolve(false);
}
};
});
return qq.promise;
};

Answer 1

you must change your query to this
MERGE ( s:Movie {attributes}.id)
ON CREATE SET s += {attributes}
ON MATCH SET s += {attributes} // optional
this should work, but you should use apoc.map.clean() so you do not set the id twice, which can cause some problems.
MERGE ( s:Movie {attributes}.id)
ON CREATE SET s += apoc.map.clean({attributes},['id'],[])

Answer 2

You can achieve this with MERGE clause as follows
MERGE (m1:Movie {id: 'gameofthrones'})
ON CREATE SET m1.genre = 'fantasy', m1.release = '2017'
MERGE (m2:Movie {id: 'inception'})
ON CREATE SET m2.genre: 'scifi', m2.release = '2010'
Ideally you want to create queries with parameters instead of literal strings. You can achieve this if you user apoc.load.json
with "file:///home/sample.json" as url // can be also http://url/sample.json
CALL apoc.load.json(url) yield value
UNWIND value as item
MERGE (m1:Movie {id: item.id})
ON CREATE SET m1.genre = item.genre, m1.release = item.release
example for dynamic properties with apoc functions:
with "file:///home/sample.json" as url // can be also http://url/sample.json
CALL apoc.load.json(url) yield value
UNWIND value as item
MERGE (m1:Movie {id: item.id})
ON CREATE SET m1 += apoc.map.clean(item,['id'],[])
or if you do not have apoc plugin:
with "file:///home/sample.json" as url // can be also http://url/sample.json
CALL apoc.load.json(url) yield value
UNWIND value as item
MERGE (m1:Movie {id: item.id})
ON CREATE SET m1 += item
note that id will first be merged and later updated with ON CREATE SET and you want to avoid writing a single property twice, using apoc and above query we can achieve that