Add Sqlitex.with_transaction and use it in Sqlitex.Server

Author: the-kenny

lib/sqlitex.ex

@@ -150,9 +150,33 @@ defmodule Sqlitex do
     exec(db, stmt, call_opts)
   end
 
+  @spec with_transaction(Sqlitex.connection, (Sqlitex.connection -> any()), Keyword.t) :: any
+  def with_transaction(db, fun, opts \\ []) do
+    with :ok <- exec(db, "begin", opts),
+      {:ok, result} <- apply_rescueing(fun, [db]),
+      :ok <- exec(db, "commit", opts)
+    do
+      {:ok, result}
+    else
+      err ->
+        :ok = exec(db, "rollback")
+        err
+    end
+  end
+
  if Version.compare(System.version, "1.3.0") == :lt do
    defp string_to_charlist(string), do: String.to_char_list(string)
  else
    defp string_to_charlist(string), do: String.to_charlist(string)
  end
+
+ ## Private Helpers
+
+ defp apply_rescueing(fun, args) do
+    try do
+      {:ok, apply(fun, args)}
+    rescue
+      error -> {:error, error}
+    end
+  end
 end

lib/sqlitex/server.ex

@@ -120,16 +120,8 @@ defmodule Sqlitex.Server do
   end
 
   def handle_call({:with_transaction, fun}, _from, {db, stmt_cache, timeout}) do
-    with :ok <- Sqlitex.exec(db, "begin"),
-          {:ok, result} <- apply_rescueing(fun, [db]),
-          :ok <- Sqlitex.exec(db, "commit")
-    do
-      {:reply, result, {db, stmt_cache, timeout}}
-    else
-      err ->
-        :ok = Sqlitex.exec(db, "rollback")
-        {:reply, err, {db, stmt_cache, timeout}}
-    end
+    result = Sqlitex.with_transaction(db, fun)
+    {:reply, result, {db, stmt_cache, timeout}}
   end
 
   def handle_cast(:stop, {db, stmt_cache, config}) do
@@ -209,20 +201,13 @@ defmodule Sqlitex.Server do
     Runs `fun` inside a transaction. If `fun` returns without raising an exception,
     the transaction will be commited via `commit`. Otherwise, `rollback` will be called.
 
-    Statements are executed in the server process and are guaranteed to get executed
-    sequentially without any interleaved statements from other processes.
-
-    It's important to use `Sqlitex.exec`, `Sqlitex.query`, ... instead of
-    `Sqlitex.Server.exec`, ... inside the transaction as the `db` arg to `fun` is of
-    type `Sqlitex.connection`.
-
     ## Examples
-      iex> {:ok, s} = Sqlitex.Server.start_link(':memory:')
-      iex> Sqlitex.Server.with_transaction(s, fn(db) ->
+      iex> {:ok, db} = Sqlitex.open(":memory:")
+      iex> Sqlitex.with_transaction(db, fn(db) ->
       ...>   Sqlitex.exec(db, "create table foo(id integer)")
       ...>   Sqlitex.exec(db, "insert into foo (id) values(42)")
       ...> end)
-      iex> Sqlitex.Server.query(s, "select * from foo")
+      iex> Sqlitex.query(db, "select * from foo")
       {:ok, [[{:id, 42}]]}
   """
   @spec with_transaction(pid(), (Sqlitex.connection -> any()), Keyword.t) :: any
@@ -254,12 +239,4 @@ defmodule Sqlitex.Server do
   end
 
   defp timeout(kwopts), do: Keyword.get(kwopts, :timeout, 5000)
-
-  defp apply_rescueing(fun, args) do
-    try do
-      {:ok, apply(fun, args)}
-    rescue
-      error -> {:error, error}
-    end
-  end
 end

test/sqlitex_test.exs

@@ -250,4 +250,31 @@ defmodule Sqlitex.Test do
     assert row[:b] == nil
     assert row[:c] == nil
   end
+
+  test "with_transaction commit" do
+    {:ok, db} = Sqlitex.open(":memory:")
+    :ok = Sqlitex.exec(db, "create table foo(id integer)")
+
+    Sqlitex.with_transaction(db, fn db ->
+      :ok = Sqlitex.exec(db, "insert into foo (id) values (42)")
+    end)
+
+    assert Sqlitex.query(db, "select * from foo") == {:ok, [[{:id, 42}]]}
+  end
+
+  test "with_transaction rollback" do
+    {:ok, db} = Sqlitex.open(':memory:')
+    :ok = Sqlitex.exec(db, "create table foo(id integer)")
+
+    try do
+      Sqlitex.with_transaction(db, fn db ->
+        :ok = Sqlitex.exec(db, "insert into foo (id) values (42)")
+        raise "Error to roll back transaction"
+      end)
+    rescue
+      _ -> nil
+    end
+
+    assert Sqlitex.query(db, "select * from foo") == {:ok, []}
+  end
 end