fix: use map instead of struct (#4)

When selecting from a subquery, Ecto returns the following error: `it is
not possible to return a struct subset of a subquery in query`. Using a
map instead of a struct results in a successful query.

lib/paginator.ex

@@ -357,7 +357,7 @@ defmodule Paginator do
       |> exclude(:preload)
       |> exclude(:select)
       |> exclude(:order_by)
-      |> select([e], struct(e, [total_count_primary_key_field]))
+      |> select([e], map(e, [total_count_primary_key_field]))
       |> subquery
       |> select(count("*"))
       |> repo.one(repo_opts)
@@ -380,7 +380,7 @@ defmodule Paginator do
       |> exclude(:select)
       |> exclude(:order_by)
       |> limit(^(total_count_limit + 1))
-      |> select([e], struct(e, [total_count_primary_key_field]))
+      |> select([e], map(e, [total_count_primary_key_field]))
       |> subquery
       |> select(count("*"))
       |> repo.one(repo_opts)

mix.exs

@@ -46,7 +46,7 @@ defmodule Paginator.Mixfile do
       {:ex_doc, "~> 0.30", only: :dev, runtime: false},
       {:ex_machina, "~> 2.1", only: :test},
       {:postgrex, "~> 0.13", optional: true},
-      {:plug_crypto, "~> 2.0.0"}
+      {:plug_crypto, "~> 1.2"}
     ]
   end
 

mix.lock

@@ -24,7 +24,7 @@
   "mimerl": {:hex, :mimerl, "1.2.0", "67e2d3f571088d5cfd3e550c383094b47159f3eee8ffa08e64106cdf5e981be3", [:rebar3], [], "hexpm", "f278585650aa581986264638ebf698f8bb19df297f66ad91b18910dfc6e19323"},
   "nimble_parsec": {:hex, :nimble_parsec, "1.3.1", "2c54013ecf170e249e9291ed0a62e5832f70a476c61da16f6aac6dca0189f2af", [:mix], [], "hexpm", "2682e3c0b2eb58d90c6375fc0cc30bc7be06f365bf72608804fb9cffa5e1b167"},
   "parse_trans": {:hex, :parse_trans, "3.4.1", "6e6aa8167cb44cc8f39441d05193be6e6f4e7c2946cb2759f015f8c56b76e5ff", [:rebar3], [], "hexpm", "620a406ce75dada827b82e453c19cf06776be266f5a67cff34e1ef2cbb60e49a"},
-  "plug_crypto": {:hex, :plug_crypto, "2.0.0", "77515cc10af06645abbfb5e6ad7a3e9714f805ae118fa1a70205f80d2d70fe73", [:mix], [], "hexpm", "53695bae57cc4e54566d993eb01074e4d894b65a3766f1c43e2c61a1b0f45ea9"},
+  "plug_crypto": {:hex, :plug_crypto, "1.2.5", "918772575e48e81e455818229bf719d4ab4181fcbf7f85b68a35620f78d89ced", [:mix], [], "hexpm", "26549a1d6345e2172eb1c233866756ae44a9609bd33ee6f99147ab3fd87fd842"},
   "postgrex": {:hex, :postgrex, "0.17.3", "c92cda8de2033a7585dae8c61b1d420a1a1322421df84da9a82a6764580c503d", [:mix], [{:db_connection, "~> 2.1", [hex: :db_connection, repo: "hexpm", optional: false]}, {:decimal, "~> 1.5 or ~> 2.0", [hex: :decimal, repo: "hexpm", optional: false]}, {:jason, "~> 1.0", [hex: :jason, repo: "hexpm", optional: true]}, {:table, "~> 0.1.0", [hex: :table, repo: "hexpm", optional: true]}], "hexpm", "946cf46935a4fdca7a81448be76ba3503cff082df42c6ec1ff16a4bdfbfb098d"},
   "ssl_verify_fun": {:hex, :ssl_verify_fun, "1.1.7", "354c321cf377240c7b8716899e182ce4890c5938111a1296add3ec74cf1715df", [:make, :mix, :rebar3], [], "hexpm", "fe4c190e8f37401d30167c8c405eda19469f34577987c76dde613e838bbc67f8"},
   "telemetry": {:hex, :telemetry, "1.2.1", "68fdfe8d8f05a8428483a97d7aab2f268aaff24b49e0f599faa091f1d4e7f61c", [:rebar3], [], "hexpm", "dad9ce9d8effc621708f99eac538ef1cbe05d6a874dd741de2e689c47feafed5"},