Add esqlite3:changes/3 function to get nr of affected rows

c_src/esqlite3_nif.c

@@ -52,6 +52,7 @@ typedef enum {
     cmd_unknown,
     cmd_open,
     cmd_exec,
+    cmd_changes,
     cmd_prepare,
     cmd_bind,
     cmd_step,
@@ -280,6 +281,18 @@ do_exec(ErlNifEnv *env, esqlite_connection *conn, const ERL_NIF_TERM arg)
     return make_atom(env, "ok");
 }
 
+/*
+ * Nr of changes
+ */
+static ERL_NIF_TERM
+do_changes(ErlNifEnv *env, esqlite_connection *conn, const ERL_NIF_TERM arg)
+{
+    int changes = sqlite3_changes(conn->db);
+
+    ERL_NIF_TERM changes_term = enif_make_int64(env, changes);
+    return make_ok_tuple(env, changes_term);
+}
+
 /*
 * insert action
 */
@@ -544,6 +557,8 @@ evaluate_command(esqlite_command *cmd, esqlite_connection *conn)
 	    return do_open(cmd->env, conn, cmd->arg);
     case cmd_exec:
 	    return do_exec(cmd->env, conn, cmd->arg);
+    case cmd_changes:
+	    return do_changes(cmd->env, conn, cmd->arg);
     case cmd_prepare:
 	    return do_prepare(cmd->env, conn, cmd->arg);
     case cmd_step:
@@ -699,6 +714,37 @@ esqlite_exec(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
     return push_command(env, db, cmd);
 }
 
+/*
+ * Count the nr of changes of last statement
+ */
+static ERL_NIF_TERM 
+esqlite_changes(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
+{
+    esqlite_connection *db;
+    esqlite_command *cmd = NULL;
+    ErlNifPid pid;
+     
+    if(argc != 3) 
+	    return enif_make_badarg(env);  
+    if(!enif_get_resource(env, argv[0], esqlite_connection_type, (void **) &db))
+	    return enif_make_badarg(env);
+    if(!enif_is_ref(env, argv[1])) 
+	    return make_error_tuple(env, "invalid_ref");
+    if(!enif_get_local_pid(env, argv[2], &pid)) 
+	    return make_error_tuple(env, "invalid_pid"); 
+    
+    cmd = command_create();
+    if(!cmd) 
+	    return make_error_tuple(env, "command_create_failed");
+     
+    /* command */
+    cmd->type = cmd_changes;
+    cmd->ref = enif_make_copy(cmd->env, argv[1]);
+    cmd->pid = pid;
+
+    return push_command(env, db, cmd);
+}
+
 static ERL_NIF_TERM
 esqlite_insert(ErlNifEnv *env, int argc, const ERL_NIF_TERM argv[])
 {
@@ -940,6 +986,7 @@ static ErlNifFunc nif_funcs[] = {
     {"start", 0, esqlite_start},
     {"open", 4, esqlite_open},
     {"exec", 4, esqlite_exec},
+    {"changes", 3, esqlite_changes},
     {"prepare", 4, esqlite_prepare},
     {"insert", 4, esqlite_insert},
     {"step", 3, esqlite_step},

src/esqlite3.erl

@@ -23,6 +23,7 @@
 %% higher-level export
 -export([open/1, open/2, 
          exec/2, exec/3,
+         changes/1, changes/2,
          insert/2,
          prepare/2, prepare/3,
          step/1, step/2, 
@@ -200,6 +201,16 @@ exec(Sql, {connection, _Ref, Connection}, Timeout) ->
     ok = esqlite3_nif:exec(Connection, Ref, self(), Sql),
     receive_answer(Ref, Timeout).
 
+%% @doc Return the number of affected rows of last statement.
+changes(Connection) ->
+    changes(Connection, ?DEFAULT_TIMEOUT).
+
+%% @doc Return the number of affected rows of last statement.
+changes({connection, _Ref, Connection}, Timeout) ->
+    Ref = make_ref(),
+    ok = esqlite3_nif:changes(Connection, Ref, self()),
+    receive_answer(Ref, Timeout).
+
 %% @doc Insert records, returns the last rowid.
 %%
 %% @spec insert(iolist(), connection()) -> {ok, integer()} |  {error, error_message()}

src/esqlite3_nif.erl

@@ -24,6 +24,7 @@
 -export([start/0,
     open/4,
     exec/4,
+    changes/3,
     insert/4,
     prepare/4,
     step/3,
@@ -70,6 +71,14 @@ open(_Db, _Ref, _Dest, _Filename) ->
 exec(_Db, _Ref, _Dest, _Sql) ->
     exit(nif_library_not_loaded).
 
+%% @doc Get the number of affected rows of last statement
+%% 
+%% When the statement is executed Dest will receive message {Ref, answer()}
+%% with answer() integer | {error, reason()}
+%%
+changes(_Db, _Ref, _Dest) ->
+    exit(nif_library_not_loaded).
+
 %% @doc
 %%
 %% @spec prepare(connection(), reference(), pid(), string()) -> ok | {error, message()}

test/esqlite_test.erl

@@ -25,11 +25,20 @@ simple_query_test() ->
     ok = esqlite3:exec("begin;", Db),
     ok = esqlite3:exec("create table test_table(one varchar(10), two int);", Db),
     ok = esqlite3:exec(["insert into test_table values(", "\"hello1\"", ",", "10" ");"], Db),
+    {ok, 1} = esqlite3:changes(Db),
+
     ok = esqlite3:exec(["insert into test_table values(", "\"hello2\"", ",", "11" ");"], Db),
+    {ok, 1} = esqlite3:changes(Db),
     ok = esqlite3:exec(["insert into test_table values(", "\"hello3\"", ",", "12" ");"], Db),
+    {ok, 1} = esqlite3:changes(Db),
     ok = esqlite3:exec(["insert into test_table values(", "\"hello4\"", ",", "13" ");"], Db),
+    {ok, 1} = esqlite3:changes(Db),
     ok = esqlite3:exec("commit;", Db),
     ok = esqlite3:exec("select * from test_table;", Db),
+
+    ok = esqlite3:exec("delete from test_table;", Db),
+    {ok, 4} = esqlite3:changes(Db),
+    
     ok.
 
 prepare_test() ->
@@ -39,6 +48,7 @@ prepare_test() ->
     {ok, Statement} = esqlite3:prepare("insert into test_table values(\"one\", 2)", Db),
     
     '$done' = esqlite3:step(Statement),
+    {ok, 1} = esqlite3:changes(Db),
 
     ok = esqlite3:exec(["insert into test_table values(", "\"hello4\"", ",", "13" ");"], Db),