Merge pull request #52 from aminroosta/nullptr

support nullptr and uniqueptr, fixes #48

Author: aminroosta

README.md

@@ -194,12 +194,43 @@ Use `std::vector<T>` to store and retrieve blob data.
 		};
 ```
 
-Dealing with NULL values
+NULL values
 =====
-If you have databases where some rows may be null, you can use boost::optional to retain the NULL value between C++ variables and the database. Note that you must enable the boost support by defining _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT befor importing the header.
+If you have databases where some rows may be null, you can use `std::unique_ptr<T>` to retain the NULL values between C++ variables and the database.
 
 ```c++
+db << "CREATE TABLE tbl (id integer,age integer, name string, img blob);";
+db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 1 << 24 << "bob" << vector<int> { 1, 2 , 3};
+unique_ptr<string> ptr_null; // you can even bind empty unique_ptr<T>
+db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 2 << nullptr << ptr_null << nullptr;
+
+db << "select age,name,img from tbl where id = 1"
+		>> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+			if(age_p == nullptr || name_p == nullptr || img_p == nullptr) {
+				cerr << "ERROR: values should not be null" << std::endl;
+			}
+
+			cout << "age:" << *age_p << " name:" << *name_p << " img:";
+			for(auto i : *img_p) cout << i << ","; cout << endl;
+		};
+
+db << "select age,name,img from tbl where id = 2"
+		>> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+			if(age_p != nullptr || name_p != nullptr || img_p != nullptr) {
+				cerr << "ERROR: values should be nullptr" << std::endl;
+				exit(EXIT_FAILURE);
+			}
+
+			cout << "OK all three values are nullptr" << endl;
+		};
+```
+
+NULL values (DEPRICATED)
+=====
+**Note: this option is deprecated and will be removed in future versions.**
+You can enable boost support by defining _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT before importing sqlite_modern_cpp header.
 
+```c++
 	#define _MODERN_SQLITE_BOOST_OPTIONAL_SUPPORT
 	#include <sqlite_modern_cpp.h>
 

hdr/sqlite_modern_cpp.h

@@ -210,8 +210,13 @@ namespace sqlite {
 
 		template<typename T> friend database_binder::chain_type& operator <<(database_binder::chain_type& db, const T& val);
 		template<typename T> friend void get_col_from_db(database_binder& db, int inx, T& val);
+		/* for vector<T> support */
 		template<typename T> friend database_binder::chain_type& operator <<(database_binder::chain_type& db, const std::vector<T>& val);
 		template<typename T> friend void get_col_from_db(database_binder& db, int inx, std::vector<T>& val);
+		/* for nullptr & unique_ptr support */
+		friend database_binder::chain_type& operator <<(database_binder::chain_type& db, std::nullptr_t);
+		template<typename T> friend database_binder::chain_type& operator <<(database_binder::chain_type& db, const std::unique_ptr<T>& val);
+		template<typename T> friend void get_col_from_db(database_binder& db, int inx, std::unique_ptr<T>& val);
 		template<typename T> friend T operator++(database_binder& db, int);
 
 
@@ -458,6 +463,35 @@ namespace sqlite {
 		}
 	}
 
+	/* for nullptr support */
+	inline database_binder::chain_type& operator <<(database_binder::chain_type& db, std::nullptr_t) {
+		int hresult;
+		if((hresult = sqlite3_bind_null(db->_stmt.get(), db->_inx)) != SQLITE_OK) {
+			exceptions::throw_sqlite_error(hresult);
+		}
+		++db->_inx;
+		return db;
+	}
+	/* for nullptr support */
+	template<typename T> inline database_binder::chain_type& operator <<(database_binder::chain_type& db, const std::unique_ptr<T>& val) {
+		if(val)
+			db << *val;
+		else
+		  db << nullptr;
+		return db;
+	}
+
+	/* for unique_ptr<T> support */
+	template<typename T> inline void get_col_from_db(database_binder& db, int inx, std::unique_ptr<T>& _ptr_) {
+		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {
+			_ptr_ = nullptr;
+		} else {
+			auto underling_ptr = new T();
+			get_col_from_db(db, inx, *underling_ptr);
+			_ptr_.reset(underling_ptr);
+		}
+	}
+
 	// std::string
 	template<> inline void get_col_from_db(database_binder& db, int inx, std::string & s) {
 		if(sqlite3_column_type(db._stmt.get(), inx) == SQLITE_NULL) {

tests/nullptr_uniqueptr.cc

@@ -0,0 +1,47 @@
+#include <iostream>
+#include <string>
+#include <vector>
+#include <sqlite_modern_cpp.h>
+using namespace std;
+using namespace sqlite;
+
+int main() {
+
+  try {
+    database db(":memory:");
+    db << "CREATE TABLE tbl (id integer,age integer, name string, img blob);";
+    db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 1 << 24 << "bob" << vector<int> { 1, 2 , 3};
+    unique_ptr<string> ptr_null;
+    db << "INSERT INTO tbl VALUES (?, ?, ?, ?);" << 2 << nullptr << ptr_null << nullptr;
+
+    db << "select age,name,img from tbl where id = 1" >> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+      if(age_p == nullptr || name_p == nullptr || img_p == nullptr) {
+        cerr << "ERROR: values should not be null" << std::endl;
+        exit(EXIT_FAILURE);
+      }
+
+      cout << "age:" << *age_p << " name:" << *name_p << " img:";
+      for(auto i : *img_p) cout << i << ","; cout << endl;
+    };
+
+    db << "select age,name,img from tbl where id = 2" >> [](unique_ptr<int> age_p, unique_ptr<string> name_p, unique_ptr<vector<int>> img_p) {
+      if(age_p != nullptr || name_p != nullptr || img_p != nullptr) {
+        cerr << "ERROR: values should be nullptr" << std::endl;
+        exit(EXIT_FAILURE);
+      }
+
+      cout << "OK all three values are nullptr" << endl;
+    };
+
+  } catch(sqlite_exception e) {
+    cout << "Sqlite error " << e.what() << endl;
+    exit(EXIT_FAILURE);
+  } catch(...) {
+    cout << "Unknown error\n";
+    exit(EXIT_FAILURE);
+  }
+
+  cout << "OK\n";
+  exit(EXIT_SUCCESS);
+  return 0;
+}