Neo4jrb Rails Project: Passing Through an Indefinite Number of Parameters to Generate Relationships

Question

I am working on a neo4j rails project that involves a parent-child type relationship between nodes from the same model. Any child can have multiple parents. I would like to be able to create the parent-child relationships when I create a new child. How should I implement this? Currently, the app is set up to only create one parent-child relationship when the child is created.

# View for ...things/new
<div class="new-thing-form">
  <%= form_for(@thing) do |f| %>
    <%= f.text_field :name, placeholder: "Thing Name" %>
    <%= text_field_tag :parent, '', placeholder: "Parent Name" %>
    <%= f.submit "Create Thing" %>
  <% end %>
</div>

# Model for Thing
  class Thing 
    include Neo4j::ActiveNode

    property :name, type: String
    property :description, type: String


    has_many :out, :children_things, type: :PARENT_OF, model_class: :Thing
    has_many :in, :parent_things, model_class: :Thing, origin: :children_things

    validates_presence_of :name
  end

I've considered three possible solutions so far and am having trouble wrapping my head around them (I am new to web development so I apologize if this is basic stuff).

1. Dynamically Add Fields

I've checked out Railscasts episode 196 and 197, however I am having trouble using "accepts_nested_attributes_for." Also, this is a relationship between nodes of the same model, so is there a way to add and remove fields without using nested attributes?

2. Create a multiselect list

There are many posts on creating multiselect menus using Bootstrap and ActiveRecord. How should I implement these using Neo4j?

3. Create ActiveRel for PARENT_OF relationship

Is there a way to create relationships through forms? If so, then is there a way to do that in conjunction with a nested_attributes method to create new PARENT_OF relationships when a child thing is created?

Sorry for the open-ended questions. I've been looking around for a couple of days now and would really appreciate some guidance, even if you can just point me in the right direction. Any advice would help. Thanks again.

Answer 1

I've not previously used accepts_nested_attributes_for myself. I know that we've discussed it in the past, but I don't recall if we ever implemented support. There is a discussion on this GitHub issue. Also feel free to stop by our Gitter chat room.

You might not need it, though. You should be able to create relationships on nodes via controller params for either has_one or has_many. Such as:

Thing.create(name: params[:thing][:name], parent_things: params[:thing][:parents])

The params[:thing][:parents] should be an array of node IDs. Then when the node is created all of the relationships should be created as well.

Of course you can also just pass in all of the params for thing:

Thing.create(name: params[:thing])

But depending on your security situation you probably want to use Rails' strong parameters to make sure people don't pass in things that they shouldn't.

EDIT:

Some view code in response to your comment:

<div class="new-thing-form">
  <%= form_for(@thing) do |f| %>
    <%= f.text_field :name, placeholder: "Thing Name" %>
    <%= text_field_tag 'thing[parent][]', '', placeholder: "Parent Name" %>
    <%= text_field_tag 'thing[parent][]', '', placeholder: "Parent Name" %>
    <%= f.submit "Create Thing" %>
  <% end %>
</div>

The f.text_field tag (I believe) will automatically make it's field name thing[name], so the text_field_tag is going along with that. By putting the [] at the end you're saying that this is going to be an array of parents. So the params Hash should be something like {thing: {name: 'Foo', parents: ['id1', 'id2']}}