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Iterate over list of objects and create nodes by properties of objects

armensanoyan
Node Clone

hi! I have a list of objects, the objects have different properties.

array = [{name: 'Armen', age: 26}, {name: 'Alex', profession: 'Scientist'}]

I need to iterate over list and create nodes with properties provided by objects. Which is the easiest and best practice way to do it? Thanks in advance! I have tried to use unwind both for list and object keys like this

with array as nodes 
unwind nodes as node
unwind keys(node) as prop 
with node, prop
merge (man: Man {prop:node[prop]}) 
return man

but in this case I get one node for each property.

1 ACCEPTED SOLUTION

Cobra
Ninja
Ninja

So, you will need to use batches to load your nodes and relationships. A batch is a list of items and you can use a batch that is 1000 or 10,000 in size depending on the power of your computer.

First, you will have to create a UNIQUE CONSTRAINT on each node Label if you have unique identifer by label. Otherwise, you can create a unique constraint on a global Label like Node if all your labels share the same index.

Then, you can load your nodes like I showed you:

WITH [{id: 0, name: 'Armen', age: 26}, {id: 1, name: 'Alex', profession: 'Scientist'}] AS nodes 
UNWIND nodes AS node
MERGE (man:Man {id: node.id})
SET man += node 
RETURN man

If you want to specify the label, then you will have to use APOC:

WITH [{labels: ["Man"], id: 0, properties: {name: 'Armen', age: 26}}, {{labels: ["Man"], id: 1,  properties: {name: 'Alex', profession: 'Scientist'}}] AS batch
UNWIND batch AS n
CALL apoc.merge.node(n.labels, n.id, n.properties, {})
YIELD node
RETURN node

Regards,
Cobra

View solution in original post

9 REPLIES 9

Cobra
Ninja
Ninja

Hello @armensanoyan

You have create your nodes with this query:

WITH [{name: 'Armen', age: 26}, {name: 'Alex', profession: 'Scientist'}] AS nodes 
UNWIND nodes AS node
CREATE (man:Man)
SET man += node 
RETURN man

But if you want to use the MERGE clause, a good practice is to have a unique identifier for each node:

WITH [{id: 0, name: 'Armen', age: 26}, {id: 1, name: 'Alex', profession: 'Scientist'}] AS nodes 
UNWIND nodes AS node
MERGE (man:Man {id: node.id})
SET man += node 
RETURN man

Regards,
Cobra

Thank you this is exactly what I need! Since I have id in my object I will use the second one to create and update by one query!

Cobra
Ninja
Ninja

Be aware that this query is not optimized if you want to load a lot of nodes, but this is the basis

Actually my plan is to load big data too, in some cases it can be millions of nodes so what is your advice for that scenario ? Thank you for warning!

Cobra
Ninja
Ninja

Do you use CSV or data are coming from a script?

No it's inside nodejs script.

Cobra
Ninja
Ninja

So, you will need to use batches to load your nodes and relationships. A batch is a list of items and you can use a batch that is 1000 or 10,000 in size depending on the power of your computer.

First, you will have to create a UNIQUE CONSTRAINT on each node Label if you have unique identifer by label. Otherwise, you can create a unique constraint on a global Label like Node if all your labels share the same index.

Then, you can load your nodes like I showed you:

WITH [{id: 0, name: 'Armen', age: 26}, {id: 1, name: 'Alex', profession: 'Scientist'}] AS nodes 
UNWIND nodes AS node
MERGE (man:Man {id: node.id})
SET man += node 
RETURN man

If you want to specify the label, then you will have to use APOC:

WITH [{labels: ["Man"], id: 0, properties: {name: 'Armen', age: 26}}, {{labels: ["Man"], id: 1,  properties: {name: 'Alex', profession: 'Scientist'}}] AS batch
UNWIND batch AS n
CALL apoc.merge.node(n.labels, n.id, n.properties, {})
YIELD node
RETURN node

Regards,
Cobra

Hi! Could you please explain what are arguments of apoc.merge.node(). I know that first one is array of labels and I assume that second one should identify the node and its' value never should changed. The third one should be properties, which should be created or updated. From documentation I didn't get what onMatchProps is for? The problem is this works for creating nodes but for updating seems like I should add fourth argument with properties to update. Thank you!
Armen

Hello @armensanoyan

I answered in your first subject.

Regards,
Cobra