CODEWITHSUNDEEP
neo4jcypher
netzstreuner
netzstreuner

Reputation: 35

neo4j: set different properties based on existing properties

I am trying to set new properties based on existing properties. The existing nodes have the following properties:

minTempC, maxTempC

New properties should be set if the following conditions are met:

minTempC < 0 set the property frosstag = true

maxTempC < 0 set the property eistag = true

maxTempC >= 30 set the property heissertag = true

The existing nodes can meet one, multiple or none of the conditions.

My cypher right now is:

//Eistag
MATCH (d:Data)
WHERE d.maxtempC < 0
SET d += {eistag:true}

//Frosttag
MATCH (d:Data)
WHERE d.mintempC < 0 
SET d += {frosttag:true}

//Heisser Tag
MATCH (d:Data)
WHERE d.maxtempC >= 30
SET d += {heisserTag:true}

Is there a way to combine these three? I have several other properties that have to be set and writing these SET clauses over and over again seems a little bit tedious. I thought of using a CASEexpression, but I am new to neo4j and must confess that I have no idea how to built such a expression.

Thank you in advance for yout tips.

Upvotes: 3

Views: 1429

Answers (1)

Stefan Armbruster
Stefan Armbruster

Reputation: 39925

You can use CASE WHEN in an expression, so the following should help:

MATCH (d:Data)
SET 
d.eistag = CASE WHEN d.minTempC < 0 THEN true END,
d.frosttag = CASE WHEN d.maxTempC < 0 THEN true END,
d.heisserTag = CASE WHEN d.maxTempC >= 0 THEN true END

Note that if the condition is false, a null is returned from CASE WHEN. Setting a property to a null value results in not setting this property.

Upvotes: 2

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