This document discusses test driven development with graph databases. It introduces the speaker as a developer and blogger interested in graph databases. It defines what a graph database is, using the labeled property graph data model. It provides an example graph about wines and discusses when graph databases are advantageous, such as for modeling highly connected data. It then presents a code kata involving creating a graph database with wine region, subregion and grape nodes and relationships to retrieve related nodes through services.

1. Test driven development with
graph databases
@SandorDargo
05/10/2017, Soiree du Test Logiciel
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2. _Father of one
_Developer at Amadeus
_Blogger – http://sandordargo.com
_Amateur of graph databases
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Who am I?

3. _Not a store of excel charts
_Not a data visualization tool
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What is not a graph database?

4. _Type of NoSQL database
_Based on the concepts introduced by Leonhard Euler
_Collections of nodes and relationships
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What is a graph(-oriented) database?

5. _Graph = Nodes + Relationships
_Property Graph = Graph + key-value
attributes/properties
_Labelled Property Graph = Property Graph + Tags/Labels
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Labelled Property Graph Data Model

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A sample graph about wines

7. _Topologies
_Social data
_Page ranking
_Analyse highly connected data (Panama papers)
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When to use a graph (i.e. advantages of a graph)?
“If you can whiteboard it, you can graph it”

8. _Graph database with three different node types
• Wine regions (e.g. Provence)
• Wine subregions (e.g. Bandol)
• Grapes (e.g. Mourvedre)
_Develop services to retrieve the nodes by name and the
related nodes
_Use Java or Python (Java 8 tonight)
_Start code for Java at:
https://github.com/sandordargo/neo-wine-
services/tree/starting-code
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Code Kata

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Creating test data with Cypher
CREATE (eger:WineRegion {name:'Eger'})-[:CONTAINS]
->(eger_subregion:WineSubRegion {name:'Eger'}),
(eger)-[:CONTAINS]->(matra:WineSubRegion {name:'Mátra'}),
(eger)-[:CONTAINS]->(bukk:WineSubRegion {name:'Bükk'}),
(eger_subregion)<-[:GROWS_AT]-(merlot:Grape {name:'Merlot'}),
(eger_subregion)<-[:GROWS_AT]-(pinot_noir:Grape {name:'Pinot Noir'}),
(eger_subregion)<-[:GROWS_AT]-(cabernet_franc:Grape {name:'Cabernet Franc'})

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Simple query with Cypher
MATCH (eger:WineRegion {name:'Eger'})-
[relationship:CONTAINS] ->
(subregion:WineSubRegion)
RETURN eger, relationship, subregion

11. _Ideal when a relationship is OPTIONAL
_Will use null for missing part of a pattern
_Example:
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OPTIONAL MATCH
MATCH (wr:WineRegion)-[:CONTAINS]→
(wsr:WineSubRegion {name:{subregionName}})
OPTIONAL MATCH (wsr)<-[:GROWS_AT]-(grape:Grape)
RETURN wr, wsr, grape

12. Thank you!
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