[Idea] Declaring an expected result for write-based Cypher queries

[Byron Ruth]

I am submitting Cypher queries over the HTTP transactional endpoint in batches and began using a pattern of adding an expected value as part of my query. For example, a query like this:

MATCH (s {foo: 1}),
      (e {bar: 1})
CREATE (s)-[:LINKS]->(e)
RETURN 1

would be submitted as:

{
    "statement": <query>,
    "parameters": null,
    "expected": 1
}

the Neo4j client I wrote inspects the result and determines in it matches the expected result. The reason this is necessary is because if either MATCH fails, the CREATE will not occur and nothing will be returned. Since an error is not raised, I use the RETURN 1 as a sentinel for determining whether the query completely executed.

I was curious if the Neo4j team had any plans for providing a return value for Cypher query execution. Or consider an approach like this in which an agent can declare an expected value.

[Michael Hunger]

You can return count(*)

which would be 0 for the case that it didn't match

and 1 for the cases it matched.

you could even do

with count(*) as c

return c = 1 as successful

Afaik there are no plans for providing expected results (esp, as those can grow gigantic).

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[Michael Hunger]

Just make sure to use labels with your property matches :)

[Byron Ruth]

Thanks Michael. The RETURN 1 approach has been working correctly for me and prevents needing to do a COUNT(*).

 

Afaik there are no plans for providing expected results (esp, as those can grow gigantic).

Yes of course :) As mentioned, I am only using this approach for write operations where no results are being returned.

[Michael Hunger]

Then you could also compare the results of the tx-endpoints in terms of nodes-created, properties-set, labels created etc.

if you provide the parameter as part of the statement { ..... "includeStats":true ... }

You get the statistics back.

HTH Michael

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[Byron Ruth]

Ah! I didn't realize includeStats was an option. That would come in handy. Thank you. 

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