Writing a Dynamic Cypher Query - Neo4j

Question

I'm working on a web project using the database neo4j. I want users to pick tags (separate nodes in the DB) and return content (also DB nodes) based on the tags selected.

I want to return to the user relevant tags based on the tags they've already selected.

The query I'm thinking of looks like this:

        MATCH (tags:tag)-[:LINKED_WITH]-(content:content)-[:LINKED_WITH]-(previousTags:tag)
        WHERE 
                //new tags must be connected to content that already selected tags are connected to
                //for as many tags as the user has already selected
            (previousTags.UID = {ID1} OR previousTags.UID = {ID2} OR previousTags.UID = {ID3}) 
                //don't include tags that have already been selected in batch of new tags
                //for as many tags as the user has already selected
            AND NOT (tags.UID = {ID1} OR tags.UID = {ID2} OR tags.UID = {ID3}) 
        RETURN tags.whatever
        LIMIT 15
        ODER BY tags.number_of_connections

Because the query depends on the number of tags the user has already selected, I have to use string building to write the query dynamically.

I have three questions about this:

Is there a way to accomplish this without string building?

Is cypher/neo4j meant to handle queries like this? (especially if the user has already selected 10-15 tags?)

Is there a better way to accomplish this?

Any insights would be greatly appreciated.

Answer 1

Remember to add an index for the tag.UID .

create constraint on (t:tag) assert t.UID is unique

You can try to use previous.UID IN {selected_tags} and pass an string array / collection but afaik that doesn't yet support index lookups. :(

So right now you'll have to stick to string building.

There is cypher-dsl for java and neo4j.rb also supports a cypher-dsl for ruby. Those might work for you, not sure if they support all you need for your query.