From 2059bfd7fd324ff9389806ef893f31e647c5604e Mon Sep 17 00:00:00 2001
From: Alexey Romanov <alexey.v.romanov@gmail.com>
Date: Thu, 28 Oct 2010 10:14:04 +0400
Subject: [PATCH] Support for BLOBs

---
 include/sqlite3.hrl   |  2 +-
 src/sqlite3_lib.erl   | 44 ++++++++++++++++++++++++++++++-------------
 test/sqlite3_test.erl | 10 ++++++++++
 3 files changed, 42 insertions(+), 14 deletions(-)

diff --git a/include/sqlite3.hrl b/include/sqlite3.hrl
index 3fd668b..24b637d 100644
--- a/include/sqlite3.hrl
+++ b/include/sqlite3.hrl
@@ -20,4 +20,4 @@
 -endif.
 
 -define(NULL_ATOM, null).
--type(sql_value() :: number() | ?NULL_ATOM | iodata()).
+-type(sql_value() :: number() | ?NULL_ATOM | iodata() | {blob, binary()}).
diff --git a/src/sqlite3_lib.erl b/src/sqlite3_lib.erl
index 7457d2e..1e2e521 100644
--- a/src/sqlite3_lib.erl
+++ b/src/sqlite3_lib.erl
@@ -11,7 +11,7 @@
 
 %% API
 -export([col_type_to_atom/1]).
--export([value_to_sql/1, value_to_sql_unsafe/1, sql_to_value/1, escape/1]).
+-export([value_to_sql/1, value_to_sql_unsafe/1, sql_to_value/1, escape/1, bin_to_hex/1]).
 -export([write_value_sql/1, write_col_sql/1]).
 -export([create_table_sql/2, create_table_sql/3, drop_table_sql/1]). 
 -export([write_sql/2, update_sql/4, update_set_sql/1, delete_sql/3]).
@@ -34,6 +34,8 @@ col_type_to_string(double) ->
     "REAL";
 col_type_to_string(real) ->
     "REAL";
+col_type_to_string(blob) ->
+    "BLOB";
 col_type_to_string(String) when is_list(String) ->
     String.
 
@@ -48,7 +50,9 @@ col_type_to_atom("INTEGER") ->
 col_type_to_atom("TEXT") ->
     text;
 col_type_to_atom("REAL") ->
-    double.
+    double;
+col_type_to_atom("BLOB") ->
+    blob.
 
 %%--------------------------------------------------------------------
 %% @spec value_to_sql_unsafe(Value :: sql_value()) -> iolist()
@@ -65,11 +69,12 @@ col_type_to_atom("REAL") ->
 %%--------------------------------------------------------------------
 -spec value_to_sql_unsafe(sql_value()) -> iolist().
 value_to_sql_unsafe(X) ->
-    if
-        is_integer(X)   -> integer_to_list(X);
-        is_float(X)     -> float_to_list(X);
-        X == ?NULL_ATOM -> "NULL";
-        true            -> [$', X, $'] %% assumes no $' inside strings!
+    case X of
+        _ when is_integer(X)   -> integer_to_list(X);
+        _ when is_float(X)     -> float_to_list(X);
+        ?NULL_ATOM -> "NULL";
+        {blob, Blob} -> ["x'", bin_to_hex(Blob), $'];
+        _            -> [$', X, $'] %% assumes no $' inside strings!
     end.
 
 %%--------------------------------------------------------------------
@@ -84,14 +89,14 @@ value_to_sql_unsafe(X) ->
 %%--------------------------------------------------------------------
 -spec value_to_sql(sql_value()) -> iolist().
 value_to_sql(X) ->
-    if
-        is_integer(X)   -> integer_to_list(X);
-        is_float(X)     -> float_to_list(X);
-        X == ?NULL_ATOM -> "NULL";
-        true            -> [$', escape(X), $']
+    case X of
+        _ when is_integer(X)   -> integer_to_list(X);
+        _ when is_float(X)     -> float_to_list(X);
+        ?NULL_ATOM -> "NULL";
+        {blob, Blob} -> ["x'", bin_to_hex(Blob), $'];
+        _            -> [$', escape(X), $']
     end.
 
-
 %%--------------------------------------------------------------------
 %% @spec sql_to_value(String :: string()) -> sql_value()
 %% @doc 
@@ -144,6 +149,16 @@ write_col_sql(Cols) ->
 -spec escape(iodata()) -> iodata().
 escape(IoData) -> re:replace(IoData, "'", "''", [global]).
 
+%%--------------------------------------------------------------------
+%% @spec bin_to_hex(Binary :: binary()) -> binary()
+%% 
+%% @doc Converts a plain binary to its hexadecimal encoding, to be
+%%      passed as a blob literal.
+%% @end
+%%--------------------------------------------------------------------
+-spec bin_to_hex(iodata()) -> binary().
+bin_to_hex(Binary) -> << <<(half_byte_to_hex(X)):8>> || <<X:4>> <= Binary>>.
+
 %%--------------------------------------------------------------------
 %% @spec update_set_sql([{Column :: atom(), Value :: sql_value()}]) -> iolist()
 %% @doc 
@@ -322,6 +337,9 @@ map_intersperse(_Fun, [], _Sep) -> [];
 map_intersperse(Fun, [Elem], _Sep) -> [Fun(Elem)];
 map_intersperse(Fun, [Head | Tail], Sep) -> [Fun(Head), Sep | map_intersperse(Fun, Tail, Sep)].
 
+half_byte_to_hex(X) when X < 10 -> $0 + X;
+half_byte_to_hex(X) -> $a + X - 10.
+
 -spec sql_number(string()) -> number() | {error, not_a_number}.
 sql_number(NumberStr) ->
     case string:to_integer(NumberStr) of
diff --git a/test/sqlite3_test.erl b/test/sqlite3_test.erl
index 24a3ffe..9ca7e1c 100644
--- a/test/sqlite3_test.erl
+++ b/test/sqlite3_test.erl
@@ -79,6 +79,16 @@ basic_functionality_test() ->
         sqlite3:drop_table(ct, user)),
     sqlite3:close(ct).
 
+blob_test() ->
+    sqlite3:open(ct),
+    drop_table_if_exists(ct, blobs),
+    sqlite3:create_table(ct, blobs, [{blob_col, blob}]),
+    sqlite3:write(ct, blobs, [{blob_col, {blob, <<0,255,1,2>>}}]),
+    ?assertEqual(
+        [{columns, ["blob_col"]}, {rows, [{<<0,255,1,2>>}]}], 
+        sqlite3:read_all(ct, blobs)),
+    sqlite3:close(ct).
+
 select_many_records_test() ->
     sqlite3:open(ct),
     drop_table_if_exists(ct, many_records),