Nested Maps and Collections in Neo4j 2

Question

I understand that node and relationship properties are limited to primitive types or arrays of primitive types. The "Maps" section of the Neo4j 2.1 Reference Card mentions that:

{name:'Alice', age:38, address:{city:'London', residential:true}}

Literal maps are declared in curly braces much like property maps. Nested maps and collections are supported.

Of course something like:

CREATE (alice {name:'Alice', age:38, address:{city:'London', residential:true}})

throws an exception:

Error: Property values can only be of primitive types or arrays thereof Neo.ClientError.Statement.InvalidType

In what context does Neo4j support nested maps and collections?

Thirty

Answer 1

(Edited)

The reference card is a bit too subtle. The most important word is "literal". In other words, you can only use arbitrarily nested maps and arrays in literals, but you cannot store such things in a node or relationship.

For example, this works:

WITH {name:'Alice', age:38, address:[{city:'London', residential:true}, {city: 'Paris', residential: false} ]} AS x
RETURN x;

But this fails:

CREATE (x {name:'Alice', age:38, address:[{city:'London', residential:true}, {city: 'Paris', residential: false} ]})
RETURN x;

Protasis

so how to store them? – Fusionism

Answer 2

There is a way to do this by converting nested maps to json string. Answered here

Butane

Answer 3

There is also a trick You can do to put a map of properties in the node like this

CREATE (x {
    `properties.name`: 'Alice', `properties.city`: 'London', `properties.residential`: true }
  )

Then in Your entity use the @CompositeProperty:

@CompositeProperty(converter = PropertiesToMapConverter.class)
    private Map<String, Object> properties;

and a converter that will convert needed types to those stored at graph DB.

Lodie