prepared statements will tell us the field count

Rakefile

@@ -1,5 +1,6 @@
 # encoding: UTF-8
 begin
+  require 'rubygems'
   require 'jeweler'
   JEWELER = Jeweler::Tasks.new do |gem|
     gem.name = "mysql2"

ext/mysql2/statement.c

@@ -30,10 +30,23 @@ static VALUE param_count(VALUE self)
   return ULL2NUM(mysql_stmt_param_count(stmt));
 }
 
+/* call-seq: stmt.field_count # => 2
+ *
+ * Returns the number of fields the prepared statement returns.
+ */
+static VALUE field_count(VALUE self)
+{
+  MYSQL_STMT * stmt;
+  Data_Get_Struct(self, MYSQL_STMT, stmt);
+
+  return UINT2NUM(mysql_stmt_field_count(stmt));
+}
+
 void init_mysql2_statement()
 {
   cMysql2Statement = rb_define_class_under(mMysql2, "Statement", rb_cObject);
 
   rb_define_method(cMysql2Statement, "prepare", prepare, 1);
   rb_define_method(cMysql2Statement, "param_count", param_count, 0);
+  rb_define_method(cMysql2Statement, "field_count", field_count, 0);
 }

spec/mysql2/statement_spec.rb

@@ -35,4 +35,13 @@ describe Mysql2::Statement do
     stmt.prepare 'SELECT 1'
     stmt.param_count.should == 0
   end
+
+  it "should tell us the field count" do
+    stmt = @client.create_statement
+    stmt.prepare 'SELECT ?, ?'
+    stmt.field_count.should == 2
+
+    stmt.prepare 'SELECT 1'
+    stmt.field_count.should == 1
+  end
 end