Trabant

** naive graph traversal for erlang and some backends like digraph dynamodb and mdigraph

• inspired by gremlin and pacer

Setup

• configure your configs

1. config/dev.exs

use Mix.Config

config :ex_aws,
  dynamodb: [
    host: "localhost",
    scheme: "http://",
    port: "8000"
    ],
  access_key_id: "abc #{__MODULE__}#{Mix.env}",
  secret_access_key: "abc #{__MODULE__}#{Mix.env}"

2. add httpoison to applications in mix.exs

def application do
    [mod: {BlogTrabant, []},
     applications: [:phoenix, :phoenix_html, :cowboy, :logger,:httpoison]]
  end

3. Add dependencies in mix.exs

  defp deps do
    [
      {:timex, "~> 0.19.2"}
      {:trabant,github: "jschoch/trabant"}
    ]
  end

4. add the backend config to your config

config/config.ex

config Trabant, backend: Ddb

5. setup your tests to clean up your db if you want

  import Trabant
  setup_all do
    Trabant.backend(Ddb)
  end
  setup do
    case Mix.env do
      :prod -> raise "can't delete prod for tests fool"
      _ ->
        delete_graph
        new
    end
    :ok
  end

    
    # change the backend, this one uses mnesia
    Trabant.backend(Mdigraph)

    #populate the graph
    graph = Hel.createG

    # pull some maps from the graph
    [alcmene] = graph |> v_id(9) |> data
    [jupiter] = graph |> v_id(2) |> data
    [pluto] = graph |> v_id(10) |> data

  
    # get all neighbors with inbound edges
    # graph is a map with info about our stuff and traversal
    # v_id(id) fetches a vertex by ID and puts it into the stream
    ins = graph |> v_id(2) 
      # in is used in Elixir.Kernel so we use inn
      |> inn 
      # [data](https://github.com/jschoch/trebant/blob/master/lib/trabant.ex#L123-L126) is a shortcut for res(graph).data
      # it grabs graph.stream and process it
      |> data

    #  get the herculese map
    [herc] = graph |> v_id(2) |> inn(%{type: :demigod}) |> data
    assert herc.id == 5

random thoughts:

thoughts on binary key conventions

id

<< id_type :: binary-size(1), id :: binary-size(16), post :: binary-size(1) >>

id_types:

atom	description
:node	normal node
:out_edge	id for an outbound edge V --:outbound_from_V--> X
:in_edge	id for an inbound edge X <--:inbound_from_v-- V
:label	special node for grouping normal nodes
:in_neighbor
:out_neightbor
:default	the default type

origin idgon.com my technology blog