Create entities if MATCH/WHERE is fulfilled

[Johnny Luu]

I have a user graph where different users have different read and write access.

If a user wants to create a new group I need to first look up if he is connected to the "Group" access node. If so, he will be able to create a new group node, else, he won't be able to do that.

Is it possible to create a new node only if a MATCH/WHERE is fulfilled (that is he is actually connected to the "Group" access node) or do I have to make two queries (one for checking and one for creating) and manage the whole IF logic in my application app?

Johnny

Sent from my iPad

[Peter Neubauer]

Johnnym
I guess you can do that with a with clause, see this snippet to insert
a value into a linked list:

CREATE zero={name:0,value:0}, two={value:2,name:2},
zero-[:LINK]->two-[:LINK]->zero
==== zero ====
MATCH zero-[:LINK*0..]->before,
after-[:LINK*0..]->zero,
before-[old:LINK]->after
WHERE before.value? <= 1 AND
1 <= after.value?
CREATE newValue={name:1,value : 1},
before-[:LINK]->newValue,
newValue-[:LINK]->after
DELETE old

Cheers,

/peter neubauer

G:  neubauer.peter
S:  peter.neubauer
P:  +46 704 106975
L:   http://www.linkedin.com/in/neubauer
T:   @peterneubauer

If you can write, you can code - @coderdojomalmo
If you can sketch, you can use a graph database - @neo4j

[Johnny Weng Luu]

That one was hard to get :)

Is an IF clause something that would be a good feature in Cypher you think so you could so something like:

START user = node(111), organization = node(112)

IF (user)-[:HAS_ACCESS]-(access {name: "Group"})

RELATE (organization)-[:HAS_GROUP]->(group {name: {name}})

Johnny

[Andres Taylor]

It was also uneccesarily complex.

The CREATE clause will run once per matching sub graph coming from the START/MATCH/WHERE before it. No matches - no create. 100 matches - 100 new nodes.

Check out this example.

Makes sense?

Andrés

[Johnny Luu]

Never knew about that.

So simple and powerful!!!

Thanks :D

Johnny

Sent from my iPad

[Johnny Luu]

And man, i really love the console.neo4j.org.

It's so simple and amazing to test things out now ^_^

Johnny

[Peter Neubauer]

Yeah,
that beast is starting to be really useful, especially with that
live-db endpoint Michael has been adding last night. Very cool!

Cheers,

/peter neubauer

G:  neubauer.peter
S:  peter.neubauer
P:  +46 704 106975
L:   http://www.linkedin.com/in/neubauer
T:   @peterneubauer

If you can write, you can code - @coderdojomalmo
If you can sketch, you can use a graph database - @neo4j

[Johnny Luu]

What's live db about?

Johnny

Sent from my iPad

[Peter Neubauer]

Oh,
it's for testing out stuff, and about an easy way to share setups and
problem descriptions. Nothing for production I fear but highly usable
even in scenarios like the manual, click on the "try this query live"
buttons in http://docs.neo4j.org/chunked/snapshot/query-where.html for
instance.

WDYT?

Cheers,

/peter neubauer

G:  neubauer.peter
S:  peter.neubauer
P:  +46 704 106975
L:   http://www.linkedin.com/in/neubauer
T:   @peterneubauer

If you can write, you can code - @coderdojomalmo
If you can sketch, you can use a graph database - @neo4j

[Michael Hunger]

What Peter means is that you can import your running, persistent neo4j db (only small ones) by using

http://console.neo4j.org?init=http://host:port/db/data/cypher

Michael

[Johnny Luu]

I just tried it and I have to say I love working with my dataset on the console.neo4j.org more than on data browser.

Hope it will be integrated soon into web admin so you can share your graph with others for collaboration and error reports.

Johnny

Sent from my iPad

[Michael Hunger]

Thanks for the feedback and all your great questions and suggestions. Really appreciated.

You can already share your graph on the console with one click as an URL.

It can also generate mutating cypher that you just have to paste into webadmin to re-create the graph in your persistent database.

And it can already import databases (as outlined below) from a running web-admin (actually by just executing a cypher statement and pulling all (or selected) nodes and rels).

I'm not really sure what else you're looking for?

Cheers

Michael

[Peter Neubauer]

Johnny,
If you feel like it, doing a short screencast ob how to use the console might be a great idea to shoe others? Loved your Node.js one :-)

Send from mobile.

[Gabriel Matei Toma]

Hey,

For a link like "http://console.neo4j.org/?init=http://127.0.0.1:7474/db/data/cypher", result is "Connection refused".

What/where do i need to setup to make it work?  

Thanks,

Gabi

[Michael Hunger]

Gabi,

it can only access publicly accessible IP's and your localhost isn't one of them :)

If you have an external IP and an open port (port forwarding) to your local machine then it works.

Alternatively you can just download rabbithole from the github project http://github.com/neo4j-contrib/rabbithole

and build and run it locally:

mvn package exec:java

it is then available at http://localhost:8080

so you can import your dataset with

http://localhost:8080?init=http://127.0.0.1:7474/db/data/cypher

Cheers

Michael

[Gabriel Matei Toma]

Thanks a lot, works like a charm!

I don't know why i thought it was more of a browser app...capable of accessing local data

[Michael Hunger]

Hmm, 

I'm not sure how far browser (javascript) apps can access local data. But actually the import is done on the server side anyway and that's out there at heroku :)

Cheers

Michael

[Gabriel Matei Toma]

Hmmm....is it possible to use local storage ? 

[Michael Hunger]

Most of the app is in server side java code as it uses a real Neo4j instance behind the scenes running cypher and other on the stored graph.

There's only a little javascript for the UI and rendering.

I assume you meant browser local storage?

Michael

[Johnny Luu]

I could absolutely do that.

I'll contact you in Skype and we can talk about it.

Johnny

Sent from my iPad

[Johnny Luu]

I feel that they are separated from each other and people don't know how to use them together. Eg there is no link from the web admin to fire up the database in the console.neo4j.org.

And what is the query for importing our database?

Johnny

Sent from my iPad

[Peter Neubauer]

Johnny,
I think the cypher query is trying to import everything form your
cypher endpoint, something like

start n = node(*) match n-[r]-() return n, r


We maybe should make that configurable, essentially turning Heroku and
console.neo4j.org into a graph view tool much like Gephi or QlikView
with cutom Cypher import?

Cheers,

/peter neubauer

G:  neubauer.peter
S:  peter.neubauer
P:  +46 704 106975
L:   http://www.linkedin.com/in/neubauer
T:   @peterneubauer

If you can write, you can code - @coderdojomalmo
If you can sketch, you can use a graph database - @neo4j