sillypog

/**
 * Speed up retrieval of rankable objects with a cache.
 *
 * We have a primary data store which implements the DataSource interface.
 * Any class implementing this interface is likely to be slow as it has to
 * fetch the data from disk or across the network. Therefore, it will be
 * useful to temporarily store some of that data in a faster, in memory
 * cache. This cache is not big enough to store all of the data from the
 * primary store though.
 *

sillypog

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="http://www.w3.org/2005/Atom">

 <title>BleacherReport articles</title>
 <link href="http://bleacherreport.com/"/>
 <link rel="self" href="http://feed.bleacherreport.com/articles"/>
 <updated>2018-07-24T18:30:02Z</updated>
 <id>urn:uuid:6ccdb64c-9ee8-47c5-bae4-9e2fb9fae183</id>
 <category term="Sport"/>

sillypog

def check_char(["3" | t], current_node) do
  if check_char(["b" | t], current_node) do
    check_char(["e" | t], current_node)
  else
    false
  end
end

sillypog

def valid_word?("", _), do: true
def valid_word?(word, tree) do
  chars = String.codepoints(word)
  case check_char(chars, tree) do
    false ->
      false
    _ ->
      [_ | t] = chars
      valid_word?(Enum.join(t), tree)
  end

sillypog

def build_tree(word_list) do
  Enum.reduce(word_list, %{}, fn(word, tree) ->
    word
    |> String.codepoints
    |> place_chars(tree)
  end)
end

def place_chars([], current_node), do: current_node
def place_chars([h | t], current_node) do

sillypog

%{
  "a" => %{"r" => %{"s" => %{"e" => %{"n" => %{"i" => %{"c" => :leaf}}}}}},
  "b" => %{
    "l" => %{"o" => %{"o" => %{"m" => %{"e" => %{"r" => %{"s" => :leaf}}}}}},
    "o" => %{
      "s" => %{"o" => %{"m" => :leaf}},
      "u" => %{"n" => %{"d" => %{"e" => %{"r" => :leaf}}}}
    }
  },
  "f" => %{"u" => %{"s" => %{"t" => %{"i" => %{"l" => %{"u" => %{"g" => %{"s" => :leaf}}}}}}}},

sillypog

iex(3)> where_string = "device_id = AAA OR login_id = 123"
"device_id = AAA OR login_id = 123"
iex(4)> query = from u in Portmeirion.User, limit: 1, select: %{warehouse_id: u.warehouse_id}, where: fragment(^where_string)
** (ArgumentError) to prevent sql injection, only a keyword list may be interpolated as the first argument to `fragment/1` with the `^` operator, got `"device_id = AAA OR login_id = 123"`
    (ecto) lib/ecto/query/builder.ex:512: Ecto.Query.Builder.keyword!/1

sillypog

defp deps do
  [{:phoenix, "~> 1.2"},
   {:phoenix_ecto, "~> 3.0"},
   ...
   {:ecto, "~> 2.1.0-rc.3", override: true},
 ]
end

sillypog

SELECT warehouse_id
FROM users as u
FULL JOIN devices AS d ON d.user_id = u.id
WHERE login_id = ? OR device_id = ? OR prism_id = ?
ORDER BY u.login_id, d.device_id, u.prism_id
LIMIT 1;

sillypog

defp where_clause(query, params) do
  allowed_params = ~w(login_id facebook_id device_id prism_id)

  key_values = params
  |> Enum.filter(fn({key, _}) -> Enum.member?(allowed_params, key) end)
  |> Enum.map(fn({key, value}) -> {String.to_existing_atom(key), cast_param(key, value)} end) # or_where expects list of tuples
  |> Enum.sort # Ensure device_id is always first if present

  where_fragment(query, key_values)
end