Query working in Neo4j Browser but not in Python Driver

Drivers & Stacks Python
1

Hi everyone, I am working on a recommender system. I am trying first some basic queries. I am stuck with the following query that works on the Neo4j Browser but it does not in Python:

"MATCH (client:Client{id:$client_id})-[:SELLS]-(product:Product{id:$product_id})"
                    "MATCH (product)-[:IN_CATEGORY]->(:Category)<-[:IN_CATEGORY]-(rec:Product)<-[i:INCLUDES]-()"
                    "WITH sum(i.quantity) AS quantity, rec.name AS recommendation"
                    "RETURN recommendation, quantity  ORDER BY quantity DESC"

Python gives me the following error message:

{code: Neo.ClientError.Statement.SyntaxError} {message: Invalid input 'c': expected 'm/M' or 't/T' (line 1, column 239 (offset: 238))

This query is inside a function where I declare both parameters. It is quite similar to a category recommendation with almost the same structure.

This is the query that works on Neo4j browser:

MATCH (client:Client{id:$clientId})-[:SELLS]-(product:Product{id:$productId})
MATCH (product)-[:IN_CATEGORY]->(:Category)<-[:IN_CATEGORY]-(rec:Product)<-[i:INCLUDES]-(order:Order)
WITH sum(i.quantity) AS quantity, rec.name AS recommendation
RETURN recommendation, quantity  ORDER BY quantity DESC

I cannot understand why the Neo4j Browser can execute the query but Python can't.

2

Hello @samsitta :slight_smile:

Did you try to write the query on one line instead of 4? Just to check if it's from the syntax or the query itself.

Regards,
Cobra

3

No, I wrote the query on 4 lines as well.

4

How are your parameters defined in Python? I would expect the syntax to be something like shown in the answer here, rather than using $:

5

Hello @samsitta

  • $var is the right way to define arguments in a query
  • are you using the Neo4j Python driver or py2neo?
  • can you try to write the query on one line?
  • if you still want to use several lines, you should put spaces at the end of the first three lines:
"MATCH (client:Client{id:$client_id})-[:SELLS]-(product:Product{id:$product_id}) "
"MATCH (product)-[:IN_CATEGORY]->(:Category)<-[:IN_CATEGORY]-(rec:Product)<-[i:INCLUDES]-() "
"WITH sum(i.quantity) AS quantity, rec.name AS recommendation "
"RETURN recommendation, quantity  ORDER BY quantity DESC"

Regards,
Cobra

6

I am using Neo4j Python Driver. I actually have already used two very similar queries and had not problem at all. I will try your suggestion to use your suggestion to use one line instead. I am using spaces at the end of the first three lines already.

8

Thank you, I tried your suggestion and it worked with writing the query on one line. Do you have any idea why it is failing when I try to write it as four lines?

9

No problem :slight_smile: could I see the Python function?

10

Sure, this is the one that finally worked:

def best_sellers(tx, client_id, product_id):
    recommendations = []
    result = tx.run("MATCH (client:Client{id:$client_id})-[:SELLS]->(product:Product{id:$product_id}) MATCH (product)-[:IN_CATEGORY]->(:Category)<-[:IN_CATEGORY]-(rec:Product)<-[i:INCLUDES]-() WITH sum(i.quantity) AS quantity, rec.name AS recommendation RETURN recommendation ORDER BY quantity DESC", client_id = client_id, product_id = product_id)
    for item in result:
        recommendations.append(item["recommendation"])
    return recommendations

with driver.session() as session:
    recommendations = session.read_transaction(best_sellers, client_id, product_id)
    for recommendation in recommendations:
        print(recommendation)```
11

Normally, these formats should work:

  • put the query on one line;
  • put the query on several lines with the triple """ at the beginning and at the end of the query;
  • put the query on several lines with one " at the beginning and at the end of each line without forgetting to put a space at the end of each line (not mandatory for the last line) like in the example of the doc.

Which version of the driver are you using?

12

For example, I am using this function and it is working just fine:

def same_category_recommendation(tx, client_id, product_id):
    recommendations = []
    result = tx.run("MATCH (client:Client{id:$client_id})-[:SELLS]-(product:Product{id:$product_id})"
                    "MATCH (product)-[:IN_CATEGORY]->(:Category)<-[:IN_CATEGORY]-(rec:Product)"
                    "RETURN rec.name AS recommendation", client_id = client_id, product_id = product_id)
    for item in result:
        recommendations.append(item["recommendation"])
    return recommendations

with driver.session() as session:
    recommendations = session.read_transaction(same_category_recommendation, client_id, product_id)
    for recommendation in recommendations:
         print(recommendation)

I am using neo4j==4.1.1

13

Indeed, that's weird, I have no more ideas but at least you have a solution when it doesn't work.

You can still create the string query before and put your query in and after call it in tx.run() :slight_smile:

14

Thx! I might do that :smiley: