Using conditional value on create statement

Neo4j Graph Platform
1

How to use conditional value something like?

CREATE (n: Nodename {
  myprop: somevalue IS NULL THEN 'abc' ELSE somevalue
})

The preceding code throws me an error:

Invalid input 'T': expected whitespace, comment, "=~", IN, STARTS, ENDS, CONTAINS, IS, '^', '*', '/', '%', '+', '-', '=', '~', "<>", "!=", '<', '>', "<=", ">=", AND, XOR, OR, ',' or '}'

I also tried like:

somevalue if somevalue else 'abc'
2

Probably best to use the coalesce function. This will return the first non-null value in a list of values provided.

CREATE
  (n:Node)
SET 
  n.myprop = coalesce(somevalue, 'abc')
3

Can we achieve something like this?

Let's say somevalue is 0:

Then it should be just 'abc'.

When somevalue is 5:
Then it should be 'abc6':

This doesn't work in this case:
coalesce('abc'+somevalue+1,'abc') // I know it's not the way

Any idea?

4

You may also look in this post what I'm trying to do for several days but not able to achieve what I wanted.

5

You want to use CASE statements here. These are used for exactly this, different expressions depending on conditionals (they can't be used for conditional Cypher execution, that's a different thing).

... // assume someValue is an integer in scope
CREATE
  (n:Node)
SET 
  n.myprop = CASE somevalue WHEN 0 THEN 'abc' WHEN 5 THEN 'abc6' END 
```

From the linked docs you can also see that it supports ELSE for a fallback, as well as a slightly more complex version where multiple separate boolean conditionals can be evaluated instead of just doing a single conditional evaluation like above.
1 Like