Add option to check if column is null by name

include/SQLiteCpp/Statement.h

@@ -435,7 +435,18 @@ class Statement
      *
      *  Throw an exception if the specified index is out of the [0, getColumnCount()) range.
      */
-    bool    isColumnNull(const int aIndex) const;
+    bool    isColumnNull(const int aIndex);
+
+    /**
+     * @brief Test if the column value is NULL
+     *
+     * @param[in] apName   Aliased name of the column, that is, the named specified in the query (not the original name)
+     *
+     * @return true if the column value is NULL
+     *
+     *  Throw an exception if the specified name is not an on of the aliased name of the columns in the result.
+     */
+    bool    isColumnNull(const char* apName);
 
     /**
      * @brief Return a pointer to the named assigned to the specified result column (potentially aliased)

src/Statement.cpp

@@ -336,13 +336,35 @@ Column  Statement::getColumn(const char* apName)
 }
 
 // Test if the column is NULL
-bool Statement::isColumnNull(const int aIndex) const
+bool Statement::isColumnNull(const int aIndex)
 {
     checkRow();
     checkIndex(aIndex);
     return (SQLITE_NULL == sqlite3_column_type(mStmtPtr, aIndex));
 }
 
+bool Statement::isColumnNull(const char* apName)
+{
+    checkRow();
+
+    if (mColumnNames.empty())
+    {
+        for (int i = 0; i < mColumnCount; ++i)
+        {
+            const char* pName = sqlite3_column_name(mStmtPtr, i);
+            mColumnNames[pName] = i;
+        }
+    }
+
+    const TColumnNames::const_iterator iIndex = mColumnNames.find(apName);
+    if (iIndex == mColumnNames.end())
+    {
+            throw SQLite::Exception("Unknown column name.");
+    }
+
+    return (SQLITE_NULL == sqlite3_column_type(mStmtPtr, (*iIndex).second));
+}
+
 // Return the named assigned to the specified result column (potentially aliased)
 const char* Statement::getColumnName(const int aIndex) const
 {

tests/Statement_test.cpp

@@ -528,6 +528,68 @@ TEST(Statement, isColumnNull) {
     EXPECT_THROW(query.isColumnNull(3), SQLite::Exception);
 }
 
+TEST(Statement, isColumnNullByName) {
+    // Create a new database
+    SQLite::Database db(":memory:", SQLITE_OPEN_READWRITE | SQLITE_OPEN_CREATE);
+    ASSERT_EQ(SQLITE_OK, db.getErrorCode());
+
+    // Create a new table
+    EXPECT_EQ(0, db.exec("CREATE TABLE test (msg TEXT, int INTEGER, double REAL)"));
+    ASSERT_EQ(SQLITE_OK, db.getErrorCode());
+
+    // Create a first row with no null values, then other rows with each time a NULL value
+    ASSERT_EQ(1, db.exec("INSERT INTO test VALUES (\"first\", 123,  0.123)"));
+    ASSERT_EQ(1, db.exec("INSERT INTO test VALUES (NULL,      123,  0.123)"));
+    ASSERT_EQ(1, db.exec("INSERT INTO test VALUES (\"first\", NULL, 0.123)"));
+    ASSERT_EQ(1, db.exec("INSERT INTO test VALUES (\"first\", 123,  NULL)"));
+
+    // Compile a SQL query
+    const std::string select("SELECT * FROM test");
+    SQLite::Statement query(db, select);
+    EXPECT_EQ(select, query.getQuery());
+    EXPECT_EQ(3, query.getColumnCount());
+
+    // Get the first non-null row
+    query.executeStep();
+    EXPECT_TRUE (query.isOk());
+    EXPECT_FALSE(query.isDone());
+    EXPECT_THROW(query.isColumnNull(""), SQLite::Exception);
+    EXPECT_EQ(false, query.isColumnNull("msg"));
+    EXPECT_EQ(false, query.isColumnNull("int"));
+    EXPECT_EQ(false, query.isColumnNull("double"));
+    EXPECT_THROW(query.isColumnNull(3), SQLite::Exception);
+
+    // Get the second row with null text
+    query.executeStep();
+    EXPECT_TRUE (query.isOk());
+    EXPECT_FALSE(query.isDone());
+    EXPECT_THROW(query.isColumnNull(""), SQLite::Exception);
+    EXPECT_EQ(true, query.isColumnNull("msg"));
+    EXPECT_EQ(false, query.isColumnNull(1));
+    EXPECT_EQ(false, query.isColumnNull("double"));
+    EXPECT_THROW(query.isColumnNull(3), SQLite::Exception);
+
+    // Get the second row with null integer
+    query.executeStep();
+    EXPECT_TRUE (query.isOk());
+    EXPECT_FALSE(query.isDone());
+    EXPECT_THROW(query.isColumnNull(""), SQLite::Exception);
+    EXPECT_EQ(false, query.isColumnNull("msg"));
+    EXPECT_EQ(true, query.isColumnNull("int"));
+    EXPECT_EQ(false, query.isColumnNull("double"));
+    EXPECT_THROW(query.isColumnNull(3), SQLite::Exception);
+
+    // Get the third row with null float
+    query.executeStep();
+    EXPECT_TRUE (query.isOk());
+    EXPECT_FALSE(query.isDone());
+    EXPECT_THROW(query.isColumnNull(""), SQLite::Exception);
+    EXPECT_EQ(false, query.isColumnNull("msg"));
+    EXPECT_EQ(false, query.isColumnNull("int"));
+    EXPECT_EQ(true, query.isColumnNull("double"));
+    EXPECT_THROW(query.isColumnNull(3), SQLite::Exception);
+}
+
 TEST(Statement, getColumnByName) {
     // Create a new database
     SQLite::Database db(":memory:", SQLite::OPEN_READWRITE|SQLite::OPEN_CREATE);