Digging

Superglue's thunks work hand-in-hand with PropsTemplate to query your JSON template for nodes. This guide helps you understand how the tools work with each other.

The props_at param

The props_at param is a keypath to nodes in your tree and is used almost exclusively with the remote thunk. On the PropsTemplate side, we pass that param over to an internal node in order to walk your templates.

?> props_at can be used with data-sg-visit, but only combined with data-sg-placeholder to build placeholders.

For example, with a template below.

path = param_to_search_path(params[:props_at])
json.data(search: path) do
  json.header do
    json.search do
      # Results is a leaf node
      json.results Post.search(params[:some_search_str])
    end
  end

  json.content do
    json.barChart do
       ...bar chart data
    end

    ...
  end

  ...
end

To fetch the json.search node, we would need to walk to data then header then search. Translating that to a remote call with a props_at param:

remote('/dashboard?props_at=data.header.search&some_search_str=haircuts')

Collections

There are two ways to query collections. Looking at the following example:

path = param_to_search_path(params[:props_at])
json.data(search: path) do
  json.posts do
    json.array! @posts do |post|
      json.details do
        json.title post.title
      end
    end
  end
end

Index-based selection

You may use an index-based key to fetch an item in a list like so:

remote('/dashboard?props_at=data.posts.0.details')

To enable this functionality, you are required to implement member_at(index) on the passed collection.

?> PropsTemplate includes a Array extension which delegates to at. If you've used the Superglue generators, it will be included in an initializer.

While traversing by index works fine, it can lead the wrong post being updated if your Redux state has changed by the time the request comes back.

Attribute-based selection

Attribute-based keys for collections look like this:

remote('/dashboard?props_at=data.posts.some_id=1.details')

Notice that we're now referencing the collection member by some_id=1 instead of index. This will fetch the node from the backend and graft it correctly in Redux.

To enable this, you are required to implement member_by(attribute, value) on the passed collection AND use the option :key in json.array!. For example:

path = param_to_search_path(params[:props_at])
json.data(search: params[:props_at]) do
  json.posts do
    json.array! @posts, key: :some_id do |post|
      json.details do
        json.title post.title
      end

      # The following will be auto appended by the key: option
      # json.some_id post.some_id
    end
  end
end

Partials

You can even query into partials.

remote('/dashboard?props_at=data.posts.some_id=1.details')

json.data(search: params[:props_at]) do
  json.posts(partial: 'list_of_posts')do
  end
end

# list_of_posts.json.props
json.array! @posts , key: :some_id do |post|
  json.details do
    json.title post.title
  end

  # The following will be auto appended by the key: option
  # json.some_id post.some_id
end

!> When querying, Superglue will disable caching and deferment until the target node is reached.

That's the basics of traversing with Superglue. Many modern SPA functionality can be achieved by just a few lines of code. For examples, see our recipes section.