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I'm working on neo4j graph with the following labels: Store, User, Product

the relationships are: (store)-[:OF]->(user), (product)-[:OF]->(user), (store)-[:SELL]->(product)

when adding or updating a store, products can be added, updated, attached or removed from the store. update can be done only if the product has no attachment to other store.

I have the following adding Store query which is working:

OPTIONAL MATCH (user: User {id: $userId} )
CREATE (store:Store)-[:OF]->(user)
SET store = $store
WITH store, user
OPTIONAL MATCH (p: Product {id: "hu1"})-[:OF]->(user)  
WITH store, p,  
CASE WHEN NOT (:Store)-[:SELL]->(p) OR                 
(:Store {id: '12asd'})-[:SELL]->(p) THEN [1]      
ELSE [] END as array              
FOREACH(
    x in array |              
    MERGE (p)-[:OF]->(user)          
    ON MATCH SET p += $product1         
    ON CREATE SET p = $product1         
    MERGE (store)-[:SELL]->(p)         
) 
RETURN store, p

(it might seem weird that one of my condition is checking the store id, when i just created it, but this query in the code handles more situations when it is needed, and i don't wont to trouble with the whole code)

the modification needed is moving the creation of the store to the FOREACH statement because, i don't wont to create the store if one of the products didn't pass one of the CASE conditions.

i tried moving the store creation inside the FOREACH statement using MERGE -

OPTIONAL MATCH (user: User {id: $userId} ) 
WITH user
OPTIONAL MATCH (p: Product {id: "1"})-[:OF]->(user)  
WITH p,  
CASE WHEN NOT (:Store)-[:ON]->(p) OR                 
(:Store {id: 'st'})-[:ON]->(p) 
THEN [1]      
ELSE [] END as array              
FOREACH(
    x in array |              
    MERGE (p)-[:OF]->(user)          
    ON MATCH SET p += $product1         
    ON CREATE SET p = $product1         
    MERGE (store:Store {id: 'st'})
    ON MATCH SET store += $store         
    ON CREATE SET store = $store         
    MERGE (store)-[:ON]->(p)         
) 
RETURN store, p

but i got this error:

Neo4jError: Variable store not defined

pointing on the store variable in the RETURN statement.

i tried adding another WITH statement between the FOREACH and the RETURN but i got the same error only pointing on the store variable in the WITH clause.

how can i declare a variable out side of the FOREACH clause so i could create node for it in the FOREACH and also use it in the RETURN ?

4

1 回答 1

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尝试在语句之外声明您的参数FOREACH：

OPTIONAL MATCH (user: User {id: $userId} ) 
WITH user
OPTIONAL MATCH (p: Product {id: "1"})-[:OF]->(user)  
WITH p,  
     CASE WHEN NOT (:Store)-[:ON]->(p) OR                 
                   (:Store {id: 'st'})-[:ON]->(p) 
                   THEN [1] ELSE [] END as array,
     $store as store,
     $product1 as product1              
FOREACH(
    x in array |              
    MERGE (p)-[:OF]->(user)          
    ON MATCH SET p += product1         
    ON CREATE SET p += product1         
    MERGE (s:Store {id: 'st'})
    ON MATCH SET s += store         
    ON CREATE SET s += store         
    MERGE (s)-[:ON]->(p)         
) 
RETURN store, p
于 2020-09-08T19:10:04.057 回答