Neo4j gem-根据参数值查询

Question

This might not be as much neo4j as it is rails. But maybe I'm wrong

I'm looking for suggestions on handling a situation when parameters are specific values. For example. In my query

@friends_events = current_user.friends.events(:e, :rel).where("rel.admin = {admin_p} AND e.size_max < {size_p}", uuid: @event_id, primary_category: params[:primary_category] ).params(admin_p: true, size_p: params[:group_max].to_i)

The event has a size_max property which can be an integer or it can be any . Right now I have any as a blank value. Basically if they choose any, I need to ignore that parameter all together in the query (or handle it in a similar fashion). A way to cheat it is to handle the situation outside and if any is selected and the value is blank, I manually set it to a really high number which won't be hit.

Not sure how to do this either inside or outside the query without an odd hacky way right now. Suggestions?

Update

I have my query as you suggested. and the methods to deal with the 'validation'

@friends_events = current_user.friends.events(:e, :rel).where("rel.admin = {admin_p} #{size_string}", uuid: @event_id, primary_category: params[:primary_category] ).params(admin_p: true, size_p: size_param)

And I changed the size_param to blank which it doesn't like. I wanted to be able to handle both cases. eg when you first hit the page params is empty, and when you submit, it's blank. Nil will work with scenario 1 and not scenario 2. Do I need a || case here?

        def size_string
          'AND e.size_max < {size_p}' if params[:group_max]
        end

        def size_param
            #has not taken in blank scenario
          params[:group_max].blank? ? false : params[:group_max].to_i
        end

and in my view I have

<% if !@friends_events.blank? %>

My error is

Don't know how to compare that. Left: 0 (Long); Right: false (Boolean) Don't know how to compare that. Left: 0 (Long); Right: false (Boolean) from the line above in my view. Changing .blank? to .nil? allows the filter to go through (though incorrectly)

Answer 1

The ways of handling it that you identified seem like the best options. It may be a little more work to evaluate it before hitting the database but you'll get a performance boost by omitting that property entirely if the user wants any . I have been told that filtering using > or <, does not use indexes, so it may be slow if you have enough records. Start with something like this:

def where_this_happens
  @friends_events = current_user.friends.events(:e, :rel)
    .where("rel.admin = {admin_p} #{size_string}", uuid: @event_id, primary_category: params[:primary_category] )
    .params(admin_p: true, size_p: size_param)
end

def size_string
  'AND e.size_max < {size_p}' unless params[:group_max].blank?
end

def size_param
  params[:group_max].nil? ? false : params[:group_max].to_i
end

There's no harm in setting the size_p param and not using it but I'm pretty sure it will bark at you if you feed it nil .