Node-Neo4j How to check if node exists(persistently)?

Question

I'm using Node-Neo4j client for my db. I want to create unique node, but I couldn't find how to do that in the documentation of Node-Neo4j. I used the logic below to check if a node exists or not:

person_param = {'name': namesurname, 'userid': userid };
person_node = db.createNode(person_param);

if (!person_node.exists){
   person_node.save(function(err, result){
       //if(err) and if(!err) stuff
   });
}

But, from what I understand, createNode creates a new node from scratch, and when I use exists on it, it just checks if the newly created node saved into database or not.

How can I check if a node with supplied properties already exists in db or not?

Thanks in advance.

score 1 · Accepted Answer · answered Apr 14 '14 at 11:40

The only solution I can think of, is the following:

Create your properties object
Query the Neo4J instance for those properties
- If a result is returned use that
- otherwise save it

In code:

var person_param = {'name': namesurname, 'userid': userid };
// Build a Cypher query
var query = [
  'MATCH (user: {name: {name}, id: {userid}})',
  'RETURN user'
].join('\n');
// use your params in the query
var params = person_param;

// Send the Cypher query
db.query(query, params, function (err, results) {
  if (err) throw err;
  // no node with such properties found
  if(!results.length){
    saveNode(params, callback)
  } else {
    // carry on with your code...
  }
});

function saveNode(person_param, callback){
  var person_node = db.createNode(person_param);
  person_node.save(function(err, result){
    //if(err) and if(!err) stuff
    // call the callback here
  });
}

The downside of this approach is that you need to build a Cypher query for each type of node you have, because there's no way (as far as I know) to pass both properties name and values to Cypher.

Node-Neo4j How to check if node exists(persistently)?

1 Answers1